Boring KTM Rebuild Thread

[El Camexican]

Exactly what the title says. There is nothing special about this rebuild, but due to some comments made in another thread I am going to try and do my part for the forum and post a benign, non-controversial thread about wrenching on a bike.

The backstory is that this was once my spare bike that was set up for single track riding, but was recently outfitted with a desert tank, headlight and some suspension changes to allow a buddy that came down to accompany me on a two day off-road adventure.

Unfortunately, as skilled a rider as he is, the bike suffered from some gravitational intervention and fell down about a dozen times, two of which were pretty serious. One of them so forceful that it pulled the pipe off of the cylinder and we had to bend it back onto the spigot using a combination of tow straps and dead fall lumber.

I’ve had a freshly Powder Coated frame sitting in my loft for a few years now, so I decided that rather than just patch together the bike with some repairs, I will give it a complete makeover and then later on refurbish the grey frame which is probably the best one I have of the four and use it on my regular bike which I suspect is tweaked at the swing-arm mounts.

So here begins the boring pictorial history of swapping parts from one frame to another, enjoy :beer

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[El Camexican]

Step one is to always clean the vehicle before starting, so given that that was done a few weeks ago we can skip directly to step two which is to grab up a bunch of plastic bags and sharpie to put hardware in and label and a pad and pen to note any parts that will need to be purchased and replaced.

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I told you this was going to be boring!

[El Camexican]

In these photos we can see the extent to which the pipe was bent. Needless to say I have no intention of trying to fix this and have sent the bill to my buddy for a brand spanking new Pro Circuit unit.

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[El Camexican]

Whoa Nelly! (As my grade 6 math teacher who had horse named Nelly would say) seems we’ve encountered an engineering deficiency!

The plastic spacers meant to hold the aftermarket radiator guards in place seem to have failed due to the heat generated just above the engine. This causes the radiator guards to wiggle around a bit which in turn causes the tank to be loose as it is connected to the radiators via the shrouds.

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The fix is to replace the melted plastic with potable water grade Mexican PVC pipe. Note the ultra accurate tenths of an inch tape measure complete with .020” increments. This is the ultimate tape measure for screwing with your know-it-all friends heads.

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No time like the present to take care of these little details so that the reassembly process can be relatively smooth. After carefully marking and cutting the pieces they are deburred with an array of specialized files and then cleaned with solvent to remove evidence of their original purpose before being tested for fit and function.

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Talk about bling!!!

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[El Camexican]

Seems on one of my friend’s spills he gave the rad a little bump. Easily straightened, but having had a rad crack on me a few years back in the middle of nowhere I prefer they not be stressed.

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Now here’s a little part worth mentioning. I installed this a while back to satisfy my curiosity about what temperatures my engine was getting to. Turns out that unless I am moving along at over 20 miles an hour my engine is constantly in the red zone. I think I liked it better when I didn’t know how hot my engine was.

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[El Camexican]

Seems neither the upper or lower chain guide rollers survived this trip. I’ve worn a few out before, but I’ve never had one fail and fall apart like this let alone both.

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You don’t have to live in Mexico or own a KTM for much time to realize that if you don’t want to interrupt your riding plans you better have a full assortment of spare parts on hand at all times.

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[El Camexican]

Seems the motorcycle Gods have thrown up another roadblock on our path to completing this project.

I noticed that the kick starter squeaked and seemed a little stiff when I went to remove it from the engine.

The culprit was this broken O-ring which allowed dirt and water to get into the mechanism.

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After a thorough cleaning the O-ring was replaced and the assembly was given a healthy coat of grease, particularly in the spring and ball housing.

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Before you guys fill up my PM box asking what kind of grease I recommend for this task, let me tell you that it is Timken brand. I swear by this grease and will continue to use it until I runout. After that I will go back to Autozone and buy the cheapest grease they have and will swear by it until I runout again. Guess you could say I’m brand loyal to the end.

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Once again having spares on hand saves the day.

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[El Camexican]

Now comes the critical moment when you remember that your swingarm bolt passes through your engine cases and therefore when you go to remove the engine your frame and front end will be left balancing on your stand at the mercy of the same gravity that necessitated this rebuild in the first place.

It is at that moment that you think back to all the times your so-called friends came over for help on their bikes and in return promised to come over anytime you needed a hand and then you remember that not one of them has the testicular fortitude to tell their wives that they would rather come over and help a friend with his bike than rub their feet all Sunday afternoon on the couch and you tell yourself for the hundredth time that that you’ll never help these sad fuks out again.

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[El Camexican]

Once you come to grips with the fact that you are going to have to do this alone, it is always recommended that you loosen any hardware that you will eventually have to take off in a less convenient position, like with your frame laying sideways on the floor.


In this instance I will be removing the low profile retaining nut on the top of the triple tree so that I can pull the bars off before I remove the engine.

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The key to not damaging a low profile nut or bolt is to just leave it alone, but if you must remove it use a socket which has been ground flat to remove the taper that normally exists to facilitate placing a socket over the head and clearing the slight radius where the hex meets the head on a normal nut.

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[El Camexican]

.... and then your wife comes down to the shop and asks what it is you’re doing that is preventing you from being upstairs and rubbing her feet and it occurs to you that a foot rub might be a small price to pay for asking her to hold onto the front end of the bike for a couple of minutes while you’re taking the whole thing apart.

This concludes our progress for today. Please stay tuned for more exciting updates as the week progresses.

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[Red Rider]

Looking good EC. I'm learning a lot. Not only on tearing down a motorcycle, but also on relationships & friendships. :cool: In the last pic, I see your KTM 3-wheeler, so I wonder how goes the progress on that?

[El Camexican]

Looking good EC. I'm learning a lot. Not only on tearing down a motorcycle, but also on relationships & friendships. :cool: In the last pic, I see your KTM 3-wheeler, so I wonder how goes the progress on that?

I’m flattered that someone with your skills would learn anything from my drivel. As far as relationships with friends go, there are at least a dozen people on here I’d trade for my current neighbors (I’m sure my neighbors feel the same way about me) and a few of my mechanically inept friends.

Life got in the way of progress on the trike about two months ago, but I intend to get back on it as soon as this bike nonsense is over. One of my biggest issues is still that darn air intake system. The more I look at it more I’m convinced that a pod filter on the carb is the only way this works.

I thought I had it figured out with that weird looking steel snorkel, but there is no room left for hardware to attach it to the plastic airbox on the fenders. This means that I would have to build a new one and reduce the size of the opening, specifically the width and that would mean that the square inches of opening on the rectangular section would be less than the square area of carb throat. I’m no engineer, but I’m pretty sure that equates to a bottleneck that would severely hampered the performance of the trike. I’ll post more details on the trike thread when I get back to it.

By the way, if anybody is having issues with my attempted tongue in cheek witticisms in these posts, try reading them in Phil Hartman’s voice as though he was narrating an informational film on the Simpsons circa “if a cow could eat you it would”

[Red Rider]

I’m flattered that someone with your skills would learn anything from my drivel.Thanks for the compliment. It's always nice to see others' techniques, so I can pick & choose the techniques that I like, and add them to my skill-set. For instance, your "low-profile nut technique" is a good idea. I never would have thought about grinding down the socket, to give it more contact area on the nut, thus reducing the chances of boogering the nut up. Brilliant sir, just brilliant!


Life got in the way of progress on the trike about two months ago, but I intend to get back on it as soon as this bike nonsense is over. One of my biggest issues is still that darn air intake system. The more I look at it more I’m convinced that a pod filter on the carb is the only way this works.Once again, I'm sorry about the extra work involved in trying to make the airbox work. I kind of feel responsible for that one. Whooopsie! :) I just hate to see pod filters on good looking builds, but if that's the only way it will work properly, then there is no other choice.


I thought I had it figured out with that weird looking steel snorkel, but there is no room left for hardware to attach it to the plastic airbox on the fenders. This means that I would have to build a new one and reduce the size of the opening, specifically the width and that would mean that the square inches of opening on the rectangular section would be less than the square area of carb throat. I’m no engineer, but I’m pretty sure that equates to a bottleneck that would severely hampered the performance of the trike. I’ll post more details on the trike thread when I get back to it.I agree. There's no use in building the snorkel, if it's going to strangle the motor, and hamper performance.


By the way, if anybody is having issues with my attempted tongue in cheek witticisms in these posts, try reading them in Phil Hartman’s voice as though he was narrating an informational film on the Simpsons circa “if a cow could eat you it would”I understood what your intent was, and I must say, it's a refreshing change from most of the threads here lately. The build threads, on the performance/sport trikes, have always been my favorite, but they've become few and far between here lately. I must admit, I was imagining the wrong voice while reading this thread. I could clearly hear Ben Stein's monotone voice as the teacher, on The Wonder Years. And strangely enough, that voice works quite well as the narrator.

[yaegerb]

Once you come to grips with the fact that you are going to have to do this alone, it is always recommended that you loosen any hardware that you will eventually have to take off in a less convenient position, like with your frame laying sideways on the floor.


In this instance I will be removing the low profile retaining nut on the top of the triple tree so that I can pull the bars off befor I remove the engine.

258642


The key to not damaging a low profile nut or bolt is to just leave it alone, but if you must remove it use a socket which has been ground flat to remove the taper that normally exists to facilitate placing a socket over the head and clearing the slight radius where the hex meets the head on a normal nut.

258641

Very cool tip. I just learned something new!

[El Camexican]

I must admit, I was imagining the wrong voice while reading this thread. I could clearly hear Ben Stein's monotone voice as the teacher, on The Wonder Years. And strangely enough, that voice works quite well as the narrator.

LMFAO! That works too LOL

I forget exactly where I learned that socket trick, but I think it was on a fork disassembly video. Now I have a bunch of them. KTM’s have a lot of low profile aluminum hardware and it’s not hard to damage them.

As far as some of the goofy detail in this thread, I’m one of what must be thousands of people that feel cheated when watching a show like American Chopper, or Overhauling and see them jump from start to finish with no one busting a knuckle. I’d rather watch someone wet sand a paint job than stare at a completed subwoofer box.

[El Camexican]

Very cool tip. I just learned something new!

As someone who considers them self the Forrest Gump of mechanics I am once again honored.

[HairyJR]

Always enjoy reading your build threads. It amazes me how you complete a certain task sometimes with the limited tools available, a backyard mechanic at heart.




.......As far as some of the goofy detail in this thread, I’m one of what must be thousands of people that feel cheated when watching a show like American Chopper, or Overhauling and see them jump from start to finish with no one busting a knuckle......

I agree with you, it's the little things an average joe watching wants to see, "how too tips" , can go to car shows to see pretty things.

"HJ" 258652 :beer

[Maico]

Once I read the words "gravitational intervention" in your first post, I was hooked! You think that KTM is a peckered knob, try restoring a '92 KTM 550 DXC. Parts are available...just not the ones you need. :)

[El Camexican]

You think that KTM is a peckered knob, try restoring a '92 KTM 550 DXC. Parts are available...just not the ones you need. :)

I can’t even imagine. Can you still get pistons and rods for those?

The first thing I say when somebody asks me about buying a used KTM is “Don’t even look at anything older than 2004” but I should probably upgrade and start saying 2009.

Speaking of old, on Monday I met the guy who sold my KTM’s bikes to the public when new in 2002 & 2003. He let the dealership go in 2007 and sells Yamaha’s now. The guy is like 60 and still rides a TZ250 on track days.

[El Camexican]

Welcome back to another fun filled weekend at Nico’s place boys and girls.

We’re starting off a little late today due to the effects of some over consumption by your host, but be assured, the Advils have kicked in and we’re feeling good enough to start thinking about a 5:00pm cocktail.

We begin today’s adventure by cleaning, straightening and installing the skid plate onto the donor frame.

First we remove as much of the spooge as possible with a woodworking tool that was bought with the best intentions yet has somehow made it into our motorcycle toolbox.

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We then follow up with a chemical cleaning using some old pre-mix we happen to have laying around and then beat and bend the part back into its original shape.

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The sound of aluminum sheet metal being beaten on the concrete floor really tests the strength of the Advil.

[El Camexican]

Next we cut strips of rubber from an old tire tube to use as insulators for the skid plate. While this is a great way to protect the paint, it’s also fantastic for reducing the amount of noise generated by a rock hitting the aluminum plate, which has been known to scare the living **** out of this guy when it happens unexpectedly.

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The easiest way to do this is to wrap the rubber approximately 1.5 times around the diameter of the tube and then put a wrap of electrical tape around it to hold it in place, but still allow it to be moved back-and-forth to avoid the mounting hardware when mounting the skid plate to the frame.

The rubber also acts as a bit of a lock washer in that it pretensions the bolts which are only holding a flimsy piece of sheet metal and can otherwise vibrate loose. I highly recommend Loctite on these threads, but that means doing a very thorough job of cleaning the threads as there is a lot of oil in this area.

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[El Camexican]

And there we have it.

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[El Camexican]

A few years ago I polished the triple clamps on this bike only to find out on the inaugural ride that the lower clamp was bent. I was so upset with myself for having gone through the effort of polishing it that I refused to polish the replacement that I bought on eBay until I had proven to myself that it was not tweaked. That was a few years ago and this will be the first time that I’ve had it off the bike, so I’m going to take the opportunity to polish it before putting it back on.

Because the forks have been recently anodized I don’t want to scratch them, so I removed the bolts and drove wedges into the clamps to open them up for easy removal.

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This is what I want it to look like when I’m done.

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I use duct tape to protect the bearing rather than remove it which is a fairly arduous task.

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[El Camexican]

We begin with removing the forging flash with grinders.

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Next we wet sand graduating from 220 to 1500

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And finally we hit the part with a buffer and wipe it clean

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It’s always a good idea to scuff all of the edges that make contact with your forks to avoid scratching. I usually do this with the 320 grit sandpaper, but you can also use small tungsten files

[El Camexican]

Before putting the triple tree back onto the forks and inserting the stem into the frame the bearing must be greased. You can’t over grease this area, especially up at the top where the water would get into it should it enter from the top of the tree.

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Always use anti-seize before inserting steel bolts into the aluminum triple tree. Because there is a spring like tension on these bolts they cannot come loose. In fact their torque recommendations are very low, something in the neighborhood of 11 and 14 foot pounds. Anything more than this and you can damage your fork tubes.

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Now we are ready to put the motor in but even though this particular engine has less than 20 hours on it I want to pull the head off and inspect it for a number of reasons. The first being that it was run with the muffler off the spigot for a period of time and I was concerned that some dust may have gotten sucked into the engine, but looking through the exhaust port everything seems nice and fresh.

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The other reason I want to remove the top end is because I suspect that even though the squish band on this engine is almost .035” tighter than stock, it could still be a little tighter. I can feel the difference between this engine and the other one at low rpm. Currently this engine has a squish of .058”.

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This engine also has a sleeve in it, and it hasn’t been properly matched, so now that I have the correct porting tools I’m going to do it right.

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[bkm]

Aound here there's gold in them there KTM's. That's the only explanation for the price people try to get out of them.

10-15 year old bikes guys are still trying to get 3k for them. And they're not nice either.

[El Camexican]

Today started with all the best intentions of turning our project into a roller, but due to unconsidered circumstances it seems this project has come to a grinding halt.

Apparently there is a difference between the EXC and SX frames and that is the provision for mounting a kickstand.

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Note the missing mount

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Well f**k me runnin, this certainly casts a cloud over our weekend, but when the KTM Gods shove oranges up yer arse, you make orange juice.

This frame will now be stripped down again and be used on the trike build and we will prep the original frame for this one.

One it is completed we will return to our regularly scheduled programing.

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[schlepp29]

Man that things gonna be sweet when it's done.

[schlepp29]

Not to be a dumb arse but could you weld up your own stand mount? That thing is to good.

[El Camexican]

Not to be a dumb arse but could you weld up your own stand mount? That thing is to good.

Could, but it would mess up the paint. Was thinking of making the trike frame orange, so fate has determined that it will be.

Update - KTM lists part# 5470300140096 for all 2000 thru 2003 250/300 EXC, MXC and SX frames. Even lists a stand for the SX :wondering

And there is no sign the tab was cut off. Weird.

[schlepp29]

Can't say I blame you. Personally I like the orange frame look and it would look great on a 3 wheeler. I made the Same mistake last year on the 1990 kx 250. While I was doing some minor welding to foot peg mounts I didn't figure in the wide foot peg dimensions. Oh well I figured I can just weld some add on pieces to the stock pegs instead of re powder coating.

[El Camexican]

Last night we began the process of prepping the frame for sandblasting.

After removing all hardware from the frame we wipe off as much grease and oil as possible before threading bolts into all the holes to protect them from sandblasting and powder coat.

In theory there is no danger in sand-blasting the threads, but I have experienced sand getting stuck inside the threads on some grease or oil residue and then ended up seizing a bolt inside the thread and snapping it off when trying to remove it. It’s just not worth the hassle unless you are sure that you can get all the sand out of the threads.

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The next step is to take some carburetor cleaner and try to spray it around all of the areas where welded parts are in contact, like where the engine mounts are welded to the frame. These areas trap grease and oil which can bleed into your powder coating once the temperatures get up to 400F.

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Once we’ve cleaned up as much of the oil as we can get in these areas the frame is pressure washed to remove the remaining dirt and oil prior to sandblasting.

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Now is a great time to go over the clean frame and look for any welders spatter or sharp edges on the metal stamping’s and remove, or buff them out. Same for and gouges or scratches. These small details are what will set your frame apart from anybody else’s, and will lessen the chance of you cutting yourself while wrenching in tight places.

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A tip for anyone who isn't sure the sandblaster got all the paint off the frame (it happens a lot around welds) Ask the PC guy to put the frame in the oven without paint for a cycle. This will cure most conventional paints and allow you to aplly PC over them. You can cure the paint with a torch as well if you notice a small spot of paint after you leave the sand blaster's.

[El Camexican]

So two weeks later and the frame is back at the sand blasters due to a piss poor first attempt at removing all the paint.

Meanwhile the closer I look at the cylinder the less I like what I’m seeing. There’s some weird wear patterns on the wall, like the cylinder isn’t round. Lots of blow-bye in the sides of the piston and almost no wear on the sides of the cylinder.

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Coincidentally I just received back a cylinder with a new sleeve and unlike the one that was on the bike I know this one was done right. I removed the rings on the piston and dropped both the old and new cylinders onto the cases to see how the piston crown lined up with the bottoms of the ports. Interesting the piston drops almost .080” below the ports on the old cylinder and on the new cylinder the piston is only a few thousands below them.

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Guessing whoever did the old cylinder didn’t sink the liner into the cylinder as far as they should have. So now the sleeve on the new cylinder needs to be matched to the ports and chamfered.

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Stay tuned for more exciting posts!

[knappyfeet]

Once you come to grips with the fact that you are going to have to do this alone, it is always recommended that you loosen any hardware that you will eventually have to take off in a less convenient position, like with your frame laying sideways on the floor.


In this instance I will be removing the low profile retaining nut on the top of the triple tree so that I can pull the bars off before I remove the engine.

258642


The key to not damaging a low profile nut or bolt is to just leave it alone, but if you must remove it use a socket which has been ground flat to remove the taper that normally exists to facilitate placing a socket over the head and clearing the slight radius where the hex meets the head on a normal nut.

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Awesome tip!!

[El Camexican]

We begin to match the liner and ports to each other using a variety of carbide tipped bits.

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The idea here is not to deviate in anyway from the factory port configuration, we simply want to match all the holes and angles up and chamfer the liner. Anyone with my porting skill level who thinks that they can improve upon the port map of a modern two-stroke likely suffers from a God complex and should not be allowed to play with these toys.

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Once all of the rough shaping is done, the same carbide tools are used to rough chamfer all the port windows and edges of the cast iron liner.

Then comes the most critical step two engine longevity, polishing the chamfers.

I like to start with these little zirconium tipped bits and do the final polish with sanding drums. I should probably mention that if you are working with a plated cylinder you should not try to do the initial chamfer with carbide bits as you may ship the plating. In that situation you would start with these less aggressive stone bits, or sanding drums.

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Remember, every edge that could possibly make contact with your piston or rings must be chamfered, that includes the base of the cylinder.

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The final chamfering step is to make sure that every single edge of the ports are slightly rounded, especially the tops and bottoms. CC Specialties has some good videos on this subject.

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When you think that you’re finished, get in there with your bare fingers and feel the edges of every port. If anything feels rougher than a wet clit you need to get back in there and polish it.

Chamfering is one area where the hobbyist porter can improve upon what comes from the factory. This task takes a lot of time and is cost prohibitive, but done properly can make your rings last considerably longer. Even when you pay to have your cylinder bored, most shops just knock off the edges with a carbide bit and call it done, so keep that in mind the next time you have a cylinder bored, or plated.

[El Camexican]

The next step is to hone the cylinder. I specifically ask my guy not to do it, that way I can clean up any little marks I make during the porting process.

There seems to be a lot of opinion about how this should be done, and I’m not saying my way is right, but I lube up the cylinder and stones with WD-40 and run the hone in and out for about 15 seconds before checking my progress.

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It is critical to enter and exit the cylinder with the hone already rotating to avoid vertical scratches. Everyone will have their own style, but I like to hold the cylinder in one hand and the drill in the other to allow the process to center itself. I also like to yell out “oh baby oh baby” when stroking the bore.

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Almost forgot to add the compression bleeding hole above the exhaust port. These things are real son of a gun to kickstart without them.

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[El Camexican]

Being that this was originally billed as a boring thread it is mandatory that we share photos of the gasket removal process.

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I assume most of us have read in our respective manuals to avoid allowing the connecting rod to come into contact with the cases when the cylinder is removed from the engine. As sinister as these warnings may appear in bold print, the reality is that short of forcefully hammering on your connecting rod the only danger that contact with the cases can result in is a slightly proud indentation where the hard steel rod has struck the soft aluminum as has happened on this engine.

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If we leave this high, or proud spot there is the possibility of an air leak forming in this location. To remove the spot I like to lay a flat file on the gasket surface and gently slid it back and forth to remove all high spots. As you can see by the shiny spots there were quite a few places that were proud.

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In order to correctly set the deck height we must first install the piston. To prevent small parts and debris from falling into the crank case I like to fold a heavy duty shop towels, or rag and snap the center. It is then pulled down over the connecting rod much like a dental dam.

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[El Camexican]

Now if this were a Wiesco piston we would be sanding all the sharp edges, but because it’s a Wossner it comes ready to install.

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This brings us to one of my least favorite part about working on engines and that is the installation of cir-clips. If there is an easy way to do this I am unaware of it. My personal multi step operation involves bleeding, swearing and intense flashlight and magnetic tool assisted searches underneath my bench. You’re on your own here kids, all I can tell you is that it’s way easier to install one of the clips in the piston before you assemble it onto the connecting rod and that it is imperative that the open end of the clip either faces straight up, or straight down to keep it from compressing at high RPM.

I also make sure that I can rotate the clip slightly in the groove after I “think” it’s in place. Once it rotates a little you know it’s properly installed.

[El Camexican]

Now comes the part where we use an assortment of base gaskets to set the deck height of the cylinder. KTM specifies a tolerance +0.00” and minus .002” or something along those lines and sells gasket that range from tissue paper thickness all the way to .035”.

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Having measured the original clearance as well as the old gasket thickness we knew that we wanted to lower the deck by .002”, so a .018” gasket was selected and we now have perfect deck height.

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Hey! What’s that on the top of the cases boys and girls!?!?! Why it’s our old friend FREE Horsepower!!!

That gasket is protruding over .070” into the crankcase, exactly where the air is supposed to pass up through the transfer ports. No matter how nice a job you do on your ports, it’s all for nothing if a detail like this is ignored. Carefully remove the excess material with a razor and be prepared to bleed.

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If you’re really serious about doing a good port job on an engine you should match the cases to the cylinder transfer ports while you are doing the port work. Unfortunately KTM uses the same cases for the 250, 300 & 380
cylinders, so there is some mis-matching built right into the design. I addressed this some years back on another engine by using epoxy to fill the void’s in the cases that were meant for the 380 cylinder. I’ve never had it on a synod, but I can feel a big difference at low rpm on that engine engine compared to any of the other 300’s I’ve built. It really feels crisp down low and likes leaner jets than the stockers.

[El Camexican]

Our last task for the weekend will be to transfer the power valve mechanism from the old cylinder to the new one.

These tiny little screws are notorious for not wanting to break loose,but I’ve gone through this enough times now that I take every precaution possible not to strip the heads. On this cylinder three of the screws came out easily, but there was one that didn’t want to, so I heated it up with a torch and that didn’t seem to work, so I gave it a smack with a blunt ended punch and it came out.

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Always a good idea to take photos of the gear tooth positions before disassembly.

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A clean power valve is a happy power valve.

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[El Camexican]

It’s been ridiculously hot here these past few days. I don’t even want to go into the shop. Temperatures aside I managed to get out and finish the cylinder on the weekend. First by setting the ring gap which on this bore should be .013”. I don’t know if the cylinder was warm, or the bore was a little on the big side, but right out of the package the gaps were .016”, so I my want to order a “B” or “C” piston next time around. Wossner offer A, B, C, D, sizes for the standard bore.

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I always take the edges off the ring ends with some fine grit paper.

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Next I set the “Z” dimension which is KTM’s fancy way of saying power valve height. In this case, 46mm from the deck is recommended. The valve “over-opens” at high rpm, so you have the option of going lower without adversely effecting your top end power. I should take a minute to brag on this system a little. Aside from the adjustable stop on the PV the actuating rod is adjustable, there are three spring weight for the centrifugal governor and an adjustment screw for the pre-load of those springs to set the precise RPM that you want the valve to open. I’m not familiar with many modern systems, but this is a far cry better than the older Yamaha systems I’ve seen.

259068

Time to paint the cylinder, All I had was some Painters Edging Tape, which isn’t sticky enough for metal. The regular stuff is much better for this task.

259069

Next we bolt the cylinder on to the cases and call it a night.

259070

[El Camexican]

What a show it was to get this frame coated. Literally had to fire the first sandblaster after his second attempt at removing all the paint. The guy had zero pride in his work, left patches all over the frame and didn’t seem to even try to get close to the welds.

Took it to another place on Saturday and they had it ready late Monday. They charge a lot, but they specialize in perfection. Dropped it at the coaters last night at it was done at 5:30 today. Probably the best job they’ve ever done for me. Took over two weeks, but it was worth it looking at this wannabe pumpkin.

259092

Time to get this project back on the rails!

[El Camexican]

Rather than risk taking boring to a whole new level I decided to skip the process of switching out the non-kickstand frame for the freshly coated original frame and engine with a new top end on it. We can now skip straight to setting the drive chain tension.

Every factory manual has a spec for this, but if you seek the ultimate in chain tension the best way to do it is to rotate your wheel until you find the tight spot on your chain and then disconnect the shock and run the swing-arm up and down through its travel range until you find the tightest point which will indicate that the rear axle is at its furthest point from the center of the transmission output shaft.

259118

You can now set the chain to be “tight” as in barely move it more than 1/2” in the center with a firm push. Between heat and sprocket wear your chain should never be tighter than this baring a dip into wet clay, or deep sand. Once it’s together make a note of how it feels and measures in a convenient location and use that for future adjustments.

[El Camexican]

Next is the part that shut us down a few weeks back when we discovered that there was no mounting provision for the kick-stand.

259119

Took long enough.

259120

While we’re here I should point out a little modification I made to reduce the noise generated by the chain slapping against the guide on the underside of the swing-arm. It’s just a rubber washer I cut out of a piece of old tire tube, but it makes a huge difference to the amount of racket going on down there over rough terrain at low speeds, which at my age are average speeds.

259121

[El Camexican]

Now it’s time to switch out the shock spring from the stocker which suits a 160 pound rider and was installed to facilitate my 140# buddy, back to the 200# lardass rated spring.

259126

Anytime I remove a shock I always take a moment to grease the Pivot Works shock spring bearing. If you aren’t familiar with these I highly recommend trying to find one for your vehicle. They add a plushness to the compression stroke that has to be felt to be appreciated. I always mount them at the highest point so as to avoid as much water and dust as possible. They come with rubber seals, but a fair bit of grease escapes anyway. They would have to be built a lot thicker in order to be perfect, but then you would have a lot of trouble getting the spring back on to the shock body.

259135

259136

Getting there....

259125

[El Camexican]

I like to torque the swing-arm/motor mount bolt first, then the lowest motor mount and then move my way up to the upper mount, or head stay.

I believe this is the most critical mount of all and is probably under more stress than any other besides the swing-arm pivot.

This particular mount should be shimmed and not just reefed into place.

On this engine & frame example there was almost a .040” gap on the right hand side of head after the upper upper bolts were torqued to the frame.

259131

Using the nearest flat washer to the size I needed, a grinder and a magnetic holder I managed to make the appropriate shim without losing too much skin from my finger tips.

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259133

Southern engineering to the rescue!

259134

[El Camexican]

I have a pet peeve regarding these bikes that relates to the way that the pipe connects to the spigot on the cylinder.

The manual shows two O-rings and every rebuild kit comes with them, but there’s nowhere for them to go that makes any sense. The result is that no matter how much silicone you use when mounting your pipe, it doesn’t take more than an hour or so of riding before signs of spooge leaking out around the spigot are visible.

This is what a stock speak it looks like and what the pipe looks like when it’s placed over it..

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259145

I decided to try welding a ring around the existing spigot that would leave a groove open for one of these O-rings to fit inside. The donor part is a factory unit that I bought brand new a few years ago and while doing a leak down test found out that the factory weld was leaking, so it needed some weld anyway.

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This is what it will look like when it is connected to the new pipe. Hopefully the O-ring won’t split.

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[Red Rider]

I'm pretty sure you're supposed to wrap a rag around the spigot/exhaust junction to contain the spooge, and then the 2 o-rings hold the rag in place. :lol:

Your fix looks nicer though. I hope it works for you as planned.

[El Camexican]

Forgot to post this up....

These carbs have a reputation for dripping fuel when ridden over rough terrain. I’ve tried a few things like crimping the tip of the tip of the tube inside the float bowl, bending it upward and raising the float to lower the fuel level in the bowl, but this little trick I found on a bike site is a much easier fix.

259151

You just route the overflow hose to loop just below the top of the main jet orifice which is well above the top of the internal overflow tube.

This isn’t a big deal for somebody who races motocross, or rides30 minute loops between Gatorade stops on their tailgates, but it’s a huge deal for anybody who is trying to get 100+ miles out of a tank of fuel when crossing the desert.

[El Camexican]

Given that the bike’s nickname is Mad Max I figured a little sinister bling was in order, so I scuffed down the pipe guard and rad protectors and dropped them off with some other parts that needed plating for some black anodizing.

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259255

Figured it would out last powder coating and can easily be redone in the future.

259256

259257

[El Camexican]

For some reason KTM decided to use a larger diameter spigot on the cylinder head of this bike than the plastic Y fitting which diverts coolant into the two radiators. No big deal, but they used a length of rad hose that fits tight on the head and loose on the plastic fitting. It works, but I can always smell antifreeze in that area when the bike gets hot and it just isn’t right.

259259

So I went to “Vatozone” on the weekend and found a hose that transitioned almost perfectly between the two diameters. Problem solved.

259260

259261

[El Camexican]

Time to put the new pipe on. First we mount the modified spigot and new mounting tabs on the frame.

Next we spray the inside of the pipe inlet with some high temp engine enamel (color’s not important) this is a poor mans substitute for thermal ceramic coating and prevents the nickel plating from discoloring when the pipe gets hot. Works better than you might think. I also put a bit of silicon on the flange in case my o-ring modification fails.

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259263

259264

Also installed the recently played foot pegs.

259265

Notice anything different? That’s right, aftermarket cotter pins! Is this thing trick or what?!?!

259266

Always trim or bend your cotter pin ends out of harms way. Drastically lessens the odds of bleeding while maintaining your ride.

[El Camexican]

So last night I thought I would finish this project up.

Started by replacing the scuffed up hand guards.

259323

259324

Ain’t dat purdy?

All that was left to do was tighten up the sub frame, put coolant into the rads and mount the tank, shrouds and seat.

As I began to pour coolant into the radiator I noticed that there was a dripping sound coming from underneath the bike. My first thought was that I had forgotten to tighten one of the hose clamps, but that “duh” moment quickly turned into a “WTF?” moment when I realized that all the fittings were tight and the coolant was spewing out of the base gasket at the front of the engine almost as fast as I was pouring it into the rad.

I have no idea what could be causing this, but I will need to completely remove the engine in order to find out as this particular model was not built to accommodate a top and rebuild without an R&R. It sucks and is one area (besides e-start) that makes the newer stuff very appealing.

I won’t be able to touch this thing again until mid August when I return from my annual fishing trip. I sure hope it’s something simple that I can laugh about later.

[Red Rider]

I sure hope it’s something simple that I can laugh about later.Bummer dude, but it's turning out sweet so far! Most likely, it's the Continuum Transfunctioner that's leaking. Pretty common issue on these KTMs.

[El Camexican]

Well, mystery solved and lesson learned. The next time I think I’m so darn good at this that I can skip the pressure test I will remind myself of this screwup.

259616

I assume I snagged the base gasket on the cylinder liner while sliding it into position. I vaguely remember having to force it a little bit while thinking that it was the O ring around the power valve rod that I was struggling against.

No matter, it’s all cleaned up and back together.

259617

[Red Rider]

Is that real phosphorus predator blood inside your motor?

[El Camexican]

Is that real phosphorus predator blood inside your motor?

Motul 2 stroke oil and Prestone pre-mix. Apparently the two combine to become a decent anticorrosion fluid. Had I used straight water in the rad I’d be in quite the pickle.

[El Camexican]

It would seem that the boring rebuild has morphed into a boring rebuild and makeover.

With our annual ride 120 miles to Cuatro Cienigas, get piss drunk, sleep, get piss drunk again and then wake up and drive 121 miles back with a killer hangover (I added one mile for the weave factor coming back) I was forced to prep the other bike which needed 2 tires, a new rim and a Lectron carb as well as some TLC so it cut the line on Mad Max and got some love this weekend.

Started with replacing the cracked and bent rim and then the rubber.

259715

Feel free to show this next photo to the next person that tells you dirt bike wheels don’t need to be balanced cuz it’s true, they don’t, especially if you like riding a pogo stick over 40mph.

259716

And now the bling as I was finally able to find some white replacement shrouds for Piñata bike. These are rarer than hens teeth on this side of the pond.

259717

I’m getting better at putting decals on. Now instead of them looking like I did the application myself it just looks like I paid some that isn’t very good at it.

259718

[Maico]

What pegs did you use? Looks like those may be some tasty treats for my '92 550 rat restore.

[El Camexican]

What pegs did you use? Looks like those may be some tasty treats for my '92 550 rat restore.

Forged steel IMS from RMATV. They come bare and rust fast, so I had them blasted and plated.

You might also want to look at a set of TUSK aluminum units. My buddy just picked up a set and they are sweet. Price is only a couple bucks over the steel pegs.

Tusk has really gotten aggressive on price and quality lately.

[Maico]

Forged steel IMS from RMATV. They come bare and rust fast, so I had them blasted and plated.

You might also want to look at a set of TUSK aluminum units. My buddy just picked up a set and they are sweet. Price is only a couple bucks over the steel pegs.

Tusk has really gotten aggressive on price and quality lately.

Were the pegs specific to your model or a retro fit from a different model ??

[El Camexican]

Were the pegs specific to your model or a retro fit from a different model ??

They were advertised and being for my bike, but as far as I know all 125 to 525 KTM's take the same pegs from 1998 to 2014 or 15. There are hundreds of aftermarket options that interchange for these years, but TUSK and IMS are the only ones I've installed.

I can take some measurements if you want to see if they'd fit your mounts.

[El Camexican]

Well, we’ll, what fun it’s been in the shop these past few evenings....

I got Mad Max assembled to the point that it could be started and against my better judgement poured in some 4 month old pre-mix and kicked it over. She fired on the second kick and after struggling for a few seconds to push out all the oil I‘d dumped into the cases after the antifreeze fiasco it ran nice and crisp. So it got pushed out of the way to await it’s new cargo rack and rad shrouds.

Piñata Bike was already assembled and waiting for fresh fuel as I didn’t really want to fill the pretty new Lectron with old gas, but I figured if the other bike started, why wouldn’t this one.

Poured in some fuel, kick, kick, kick, kick, think it fired? Kick, kick, kick. God my foot hurts, go get MX boot. Kick, kick, kick, kick, take a brake and curse the carb out. Kick, kick, kick, kick, kick. Stop to rest, sweat is running down my butt crack like a spring brook. kick kick, kick, kick, my knee feels like it’s bleeding internally, kick, kick, kick, kick Stop to remember Billy’s video of him trying to start his Rotax. Kick, kick, kick, kick, kick, WTF!!!!!

Pull the plug, it’s a little wet, but nothing serious, should probably check for spark even though I didn’t touch the wiring and drove it up onto the trailer the last time I used it. Bingo! No spark!!!

Change plug, no spark. Change coil, no spark, change CDI, no spark, change little aluminum thing with two wires, no spark, swap out the stator, spark!!!

Fired on the second kick, but didn’t run until I tried closing the choke. Seems it either doesn’t need choke at 100 degrees, or it’s richer than Bill Gates. Once running with the idle set it feels really crisp, going to take out out on the weekend for a test rip.

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259763

[El Camexican]

As always, the best part of any thrash is shuffle playing some Van Halen just loud enough to let the neighbors know that narco corrido accordion sh*t don’t fly in this vato guerros shop and cleaning up the mess.

259764

Time too get ready for....

259765

You guessed it, another boring KTM rebuild.

[bkm]

I need to turn your OCD loose in my garage one weekend.

[El Camexican]

This took boring to a whole new level.

Should have been done 2 weeks ago, but the local shop that had, and I quote ‘all the parts in stock’ ended up having one gasket and one seal only, so RMATV got the call.

Cheesy little unit, cool as all heck, but if you want something that your kid can just add gas to and drive all summer without you needing to pour money into this is not the bike you want. I doubt this has 50 hours on it and it’s on its second set of starter parts at $200 plus labor a pop and the rings are so worn I can turn it over with two fingers. I don’t know if it will even start.

260017

260018

260019

[El Camexican]

I seem to be trapped in a perpetual cycle of rebuilds.

After popping my engine I decided that I may as well swap out what I believe is my tweeted frame for what I hope isn’t a tweaked frame. As well, I have a swing-arm that’s in pretty good shape, so I figured I may as well go the entire 10 yards and swap the engine, frame and swinger all at once.

Here’s the frame In the oven this morning.

260113

And after...

260114

Some years ago I made a personal vow to never polish another swing-arm. I broke that vow today and as much as I like a polished swinger, it bothers me that I could have helped a few hundred old ladies cross the street, or donated blood twice during the time that it took to sand the pits out of this thing.

260115

[fieldy]

That's a large oven.

[El Camexican]

That's a large oven.

They have two ovens side by side running 12 hours a day. The quality is iffy, I always end up with some contaminates in my paint, but the price is right. $150 Pesos, or $8.00 US bucks a frame if I supply the powder, so I don't complain.

[Red Rider]

... it bothers me that I could have helped a few hundred old ladies cross the street, or donated blood twice during the time that it took to sand the pits out of this thing.The fact that you are refurbishing basketball courts though, should not be overlooked.

[El Camexican]

The fact that you are refurbishing basketball courts though, should not be overlooked.

Took
Me a minute to figure out what you meant. I didn’t recognize what they were when I took the photo.

[ironchop]

The fact that you are refurbishing basketball courts though, should not be overlooked.Yeah that's what I thought too..... It was very generous of El Camex to donate all that KTM orange for the Mexican Parks and Rec Dept whether he was aware of it beforehand or not [emoji23]

Sent from my Z958 using Tapatalk

[El Camexican]

Mad Max is finally done. Some black anodizing on a new rack and Wolfman bag as well as some Mad Max ink.

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260266

Piñata Bike is next.

[ironchop]

Nice work! Looks fantastic

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[El Camexican]

Nice work! Looks fantastic

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When are you coming to ride it?

[ironchop]

When are you coming to ride it?Much sooner if it wasn't a four day drive to your house from here [emoji16]

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[El Camexican]

Much sooner if it wasn't a four day drive to your house from here [emoji16]

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That’s just a detail. Maybe I’ll get s chance to talk you into at the dunes next year.