double suzuki lt250s rebuild

[ktmbk]

I figured that I'll put my fall/winter project up for all to see and maybe get some ideas on it.

I now have two 1989 Suzuki lt250s quadsport quads. One I have had for 8-9 years or so, the other I recently bought as a parts bike.

My old one has never run quite right, I've tried to fix it at various times over the last decade or so. After a while I usually give up on it and let her sit for a while. I was never able to figure it out, timing? carb? it ran at times but the exhaust pipe got hot and glew red within a few minutes and then it shut off. I did rebuilt it completely - engine and chasis, about 7 years ago, maybe have two hours ride time on it since then. Unfortunately years of sitting means it could use a freshening up.
I bought the new one as a parts bike, missing the front wheels among other things. I got the engine in parts in a box, and have yet to get the pipe and I'm sure other stuff for it. It's a basic basket case, To fix it will need basically every bearing, bushing, and at least one tie rod. Then there's the frame, yea a crack, its in one of the vertical tubes at a seam, but the tube isn't broken through and it looks fixable. So why did I buy it? For the engine. The engine ran, but burnt oil badly. The engine was taken apart to replace the valve stem seals in a attempt to fix this, then the owner lost interest (he had recently purchased it himself). Simply, my idea was re-assemble the engine and swap it into my bike.
I took off the clutch from the new motor and ran it through the parts washer, after getting the inch of mud and oil off it, it was in great shape, needed almost every seal, but was very usable. I even found out the reason for the oil burning, someone put standard set of rings on a over sized piston, oops. After pricing my wish list I found out it would cost about $200 to do right, well my project fund is low at this point - so I did the best I could: I took some stuff from the new engine and swapped out the suspect stuff from my old engine. Went through my carb, some new gaskets, a new flywheel key (I checked it on a hunch-it's broken before), and within three kicks it started, hey not too bad for this bike, it usually me fights to start it. It ran well , at a high idle for about four minutes, then stalled with a metallic pop, or ping (the type that makes your stomach sink). Well I kicked her over right away, it didn't start, but it wasn't seized. After much thought I think I know whats wrong, and maybe it's whats wrong the whole time.
Well that's most of the history, at this point I'm waiting for parts to show. I ordered what was needed the get the new engine together, and using the parts from the old engine (which turned out to be good) I should have a good engine there. I also got what I think I need for the old one.
I'm not sure what I'll end up with. worst case one cleaned up bike, best case is two bikes. It's going to have to be a cheep rebuild at this point, I may even have to sell the new one to finish the old, we will see.
Here's some picts, my origional one has the nerf nets on it.

[ktmbk]

Ok, I got the parts I was waiting on, but it's going to be raining most of the week so I wont be able to work on the old one (figures I'm on vacation), I got the new frame over to my friend to have her mig welded. He says he thinks it will be fine, he's seen worse.
I got the new engine back together with a little help from my bro-in-law. Came out good, just needs two cam bolts/washers and a seal to be 100%.

[ktmbk]

Here is some problems I ran into that I wanted to point out for anyone doing similar work:
Here's a pict of the oil filter seals, it shows that the old (black) has swelled out nearly twice as thick as the new (orange) and is a good example of why you don't skimp on these, with some work the old can fit into the housing but why risk it?



This shows the old cam chain slider and tensioner, the slider was installed backwards and the tensioner had groves worn into it trying to keep the chain tight. In addition I found the chain streached out nearly a cm, It was so bad I was not able to get any tension from the tensioner and it was not possible to set timing at all.I had a good extra chain from the build on my first bike which I used.


Other than the surprise stud spinning out (heli-coiled in the past - a quick fix), and some missing hardware, putting it together went smoothly.
I should note the previous owner disassembled it to go after a oil burning problem, even had the valve stems replaced to try and fix it - the real issue was from putting std size rings on an over sized piston causing blowby. I was told it ran like this, I can't see how, but it did. I know the guy and he did not have the bike for long befor he lost interest in it, and this is how he got it. The real fault lies with the last guy that put the engine together since he made the mistakes. The damage was fixable, but it just shows that an engine is as good as the people who work on it.

[MonroeMike]

Quite a project. It makes it harder having to fix other peoples errors.

[ktmbk]

Quite a project. It makes it harder having to fix other peoples errors.

Thanks, you'll get to see one of my own errors soon. Ha ha ha...

[ktmbk]

Here was evening project, 2 carbs. One was originally off my first bike, one was off my new bike. The original was replaced with another that was in better shape in the coarse of diagnosis and now is a spare. I took this carb apart about three months ago to look it over. The new bike's carb was taken apart about a month ago. When I rebuild carbs I clean then and tape each piece to paper, noting what or where they are, and any settings they are set to as I remove them. I find that this helps me rebuild them whether a day or a year later. I also print up a parts diagram off a dealers web sights, I find they help find any missing pieces and give a idea of the correct way to put them together, I also try to have a manual, oem if possible. They help you put them together and will give you base settings, but beware that the aftermarket style usually covers several similar bikes sometimes they are not always accurate.
Here is my start point, I try to have a large clean area, you will see both carbs and how I laid them out when I took them apart. I have new seals and gaskets. My idea is take the best from both and assemble one for the engine I recently assembled. The second carb will end up as a spare or perhaps sold.

There are a lot of people who will tell you how to do this, so I'll go through this quick, here is the body:

Bottom first - the jets and float:

Then the bowl :

Then the choke:

there is some concern how to put the choke lever together, The pictures aren't always clear, here is what I came up with:

The extra thing on the side for the choke is a winter/summer choke adjuster, pull it out for winter starting and it will let the choke open more - talk about over engineered - carbs should be as simple as possible.
Now the needle, slide, and top:

I'm not going to show how they go together since the parts diagram is accurate here, the trick is to follow it exactly since these over designed carbs seem to have a lot of extra parts put into them.
here is the results:


And then there's carb 2, this is the original one in my old bike this will be the spare since I had to epoxy a steel tube into it for a fuel intake tube in the past:



hopefully you will end up a empty paper sheet (only exception here is would be what was replaced), I now have three of these sheets for the same type of carb body, the third was from the carb that is on my old quad now, I did this one a few months ago and for some reason never got rid of it.

[ktmbk]

Finally had a good day to check on the engine in my origionial quad, I was correct on my hunch of what was wrong, and it's my fault. The flywheel key snapped causing the timing to change. Here is how I changed the key:

First the cover comes off:
http://www.3wheelerworld.com/attachm...hmentid=106434
then the flywheel, The fault was i didn't torque it correct, and never had, which may be the problem the whole time with this bike. results one snapped key. The nut and flywheel came off by hand, not so good:

http://www.3wheelerworld.com/attachm...hmentid=106435

Be sure to clean the whole area:

and a new key:

Be sure to clean the shaft good, use locktight on the nut, and torque it to specks. The spanner wrench I got was not correct, great, so I was unable to use it (Not being able to hold the flywheel properly to torque the nut was my problem the whole time). Improvise.... I as still able torque it to specs, but not without some issue - I broke a piece of the internal case off. Lucky, It was a part that was not important, it was moulded to fit the tensioner slide and not functional to the engine operation. This case was also damaged (then repaired) at one point by the dreaded chain slippage issue these bikes tend to have, I have a new set in reserve so I'm not so concerned, If I get board someday I'll swap out the internal cases, For now it's too much of a pia to do.

Put on the cover, new gasket and close it up. Note here I went heavy on the silicone sealant, you are not suppose to do this, however I did to insure a leak proof seal due to the case damage noted above.

Tighten the bolts and wait for everything to set. Hopefully I will be able to start it tomorrow without a problem. The top end was not affected by the key, just spark timing, so all should be well.

[ktmbk]

Here's some back posts for anybody interested in a little history on my bike. Some of my posts may go back a deckade or so. I'll put them up as I find them.

http://www.suzukiatvforums.com/forum...ead.php?t=1133

http://forums.off-road.com/atv-loung...quadsport.html

awesome the above post was in the top 3 in a Google search, this thread comes up as #12.

[ktmbk]

I waited until yesterday to start my origional quad up, I wanted the silicone to seal properly. I ended up kicking her for two min then got her running - at a high idle for then let her run for another 2 min befor shutting her off.
Today I had a little more time so i started her up (5 kicks) and let he run a while. The high idle never dropped, and the bike responded to the throttle, but backfired out both the pipe and carb, also the exhaust pipe started to glow red by the engine. I was able to adjust the air screw to drop down the rpm's a little, but the pilot screw had no affect when adjusted. The idle was still really high. I put the choke on full and the bike's idle dropped to almost normal, the bike responded well to the throttle, and the pipe actually stopped glowing. The air screw still had some response to it, but the pilot still did not.
I have an idea of what's next, but please if anybody have any ideas on to throw out, let me know.

[ktmbk]

Another day of disappointment.
I started working on the bike for what I thought would be a carb issue and didn't even get far enough to find out if I was right or not. I started with making sure the throttle cable was routed correct, which it wasn't, so I figured I was off to a good start. After starting it,The seal for the clutch blew out, and took the whole clutch arm with it.
I checked, aperantly nothing holds this in, **************.
Well It seems that the T in the engine vent hose somehow had mud clogging it up, the pressure had to go somewhere, out the seal it went. Well, I figured that I could just clear the T out, line up the clutch splines, and put the arm back in. Well After I couldnt line up the splines with a few engine spins I took a light and looked into the hole and I was not happy with what I saw. A ******* spring at the bottom of the case. Yea a ******* spring.
Well I spun the engine over again, looking into the case, and sure enough there was a missing clutch bolt. It somehow backed it's way out or sheered off.****.
Well isn't this just great.
I'm going to do the easier choice, I'm swapping out the engine for the one I recently rebuilt. It's faster and I can't afford to take the other apart and find out there is something I cant fix without leaving it open -then have it rain-. I'll fix this on the bench.
Sorry no picts on this one, the other engine is sitting in the frame already waiting to be bolted in.
All I want is a running bike at this point. I guess the old saying on these bikes are true, either there **** or run forever.
Oh yea, it's raining now.

[MTS]

Off To a decent start, It can be Frustrating sometimes with problems like that... If you solved the timing issue with the new guides and setting it again...I would be taking a close look at that Cam-shaft and intake track....(seems i red you replaced the valves?) Also noticed Silicone on the rocker cover...Have to be Real careful with that as it can block Oil passages to the Cam on them If i remember right.

[ktmbk]

Off To a decent start, It can be Frustrating sometimes with problems like that... If you solved the timing issue with the new guides and setting it again...I would be taking a close look at that Cam-shaft and intake track....(seems i red you replaced the valves?) Also noticed Silicone on the rocker cover...Have to be Real careful with that as it can block Oil passages to the Cam on them If i remember right.

Yea, I know, silicone is used on the rocker cover as per Suzuki, Some say to go light but I always seem to add a little extra.You have to let it sit a few days to make sure it's cured, and be sure to use the good stuff. It can definitively gum stuff up if it breaks free. I'm more worried about the silicone on lower case on the original engine since I went really heavy to make up for the case damage. I didn't do the valves, but I'll double check it to make sure of any problems when I take it apart.

I may be getting people confused on the fact that I have two engine's I'm playing with, I do tend to drone on after all. The one I put together above with the new guides is new to me, came with my parts bike, and was in parts in a box when I got it. the one I just changed the flywheel key on is out of my original bike, I went through it A long time ago, spent a lot of money on things like a new crank, bearings, complete top end etc... and got almost no run time out of it.
To make it more confusing I am putting the new engine into my old frame. It's time to start fresh, it's the best thing to do sometimes.
I'm interested in what the failure was with the spring in the old engine, but for lack of time and money I'll look into that later. I'll claim any fault with the old engine, but I do know that I used blue lock tight on the clutch spring bolts when I assembled it.

So far I got the lower rear mounting bolt in on the new engine, took me an hour and a half to shim it just so, and I'm still not sure it'd right. You need to make sure it's right to avoid throwing the chain and breaking the case. I also got the top mount on the cylinder on. I ran out of sunlight, at least my wife was bringing me some Dogfish 90's while I was doing it to help my frustration.

[ktmbk]

Well the engine's in, cleaned an soaked the chain off the bike, put it back on yesterday, and she ran first kick. Idled her for a while and shut her off (did this 2 or 3 times), adjusted the carb, topped off the oil, and took her up and down the trail. Felt good, best ride on it for the ten years I had it. I didn't want to go too crazy yet, still have to put on the plastics and work out some stuff.

[ktmbk]

Ran her a few times now. She still needs some things worked out but she's solid enough to put together. Least I can ride her now, for now I'll keep her together. Time to dig deep into the second bike, I'll get back into this one after I get the second almost finished.
Here is some pict's of the plastics going on:

[ktmbk]

And what happened with the other engine?

Not happy about it, but it's fixes now. This engine is waiting to go into the other frame when I get it back.