Barnboy's 1984 ATC200M Rebuild

[BarnBoy]

Nice to see you are making progress to! I was just finishing up my 82 200E build today when i got asked to put a top end refresh on another motor for a guy, and then when i found out whats wrong with it i came post hunting because if i recall correctly you did a bushing on the cam journal in your 200M build didn't you? Browsed through the thread, saw pictures of it fixtured on the mill and after the machining, but i didn't see any pictures of how it turned out with the cam installed. How did you affix the bushing so it can't slide side to side or is it a tight fit when the rocker cover is torqued down?

I got a head coming to look at that has a badly worn cam journal, and i have a couple more in my spare parts bucket, i would like to start saving these if i can mill them and put in a bushing i just haven't been able to find any details of someone doing it. I have a mill and lathe at home so i can make and machine anything i want, just need some direction on how its being done, what bushing material was used, etc. I could easily fixture plate to my mill and run the boring head through to clean it up, i do a lot of small machining jobs like that.

Hey Scott, sending you a PM. I thought I updated that last thread but I guess not, I'll go back and check and also dig up those pics.

[BarnBoy]

Here's one pic I had on my phone. I'll have to look on my old phone, it should have the rest.

[kb0nly]

Just got your PM and noticed your post here. That looks nice, the bronze bushing is pinched in place by the rocker cover then? I was looking at this and figured i could fixture the head and rocker cover with four long bolts through like the studs on the motor, torque them down to spec so i know the rocker cover is pinched down like it will be installed, then bore out for the bushing, make the bushing a bit undersized for the cam bore and install it and torque down again and then final size the bushing for the cam size while its all torqued down, should give me a reasonable result.

I have some bronze bushing/bearing material in various sizes, haven't checked if i got anything the right size yet. Luckily it appears the bore of the opening for the advancer base is concentric to the cam bore, the one i have to try this on is worn so bad that the heads cam bearing surface is worn at an angle and material is rolled over the front edge. I think they ran it without oil for a while.

[BarnBoy]

Just got your PM and noticed your post here. That looks nice, the bronze bushing is pinched in place by the rocker cover then? I was looking at this and figured i could fixture the head and rocker cover with four long bolts through like the studs on the motor, torque them down to spec so i know the rocker cover is pinched down like it will be installed, then bore out for the bushing, make the bushing a bit undersized for the cam bore and install it and torque down again and then final size the bushing for the cam size while its all torqued down, should give me a reasonable result.

I have some bronze bushing/bearing material in various sizes, haven't checked if i got anything the right size yet. Luckily it appears the bore of the opening for the advancer base is concentric to the cam bore, the one i have to try this on is worn so bad that the heads cam bearing surface is worn at an angle and material is rolled over the front edge. I think they ran it without oil for a while.

The bronze bushing is pinched but also pinned to the head with a steel pin. Thats the safest way to do it. You want about a 0.001" interference fit from the OD of your bushing and the ID of the bore in head, with the pin. Make the whole bushing on the lathe, I wouldnt pinch and bore on the mill unless you were not going to pin it. If you don't pin it, you better cut a shoulder in the head on one side at least to locate that bushing, you don't want to chance it sliding at all inside.

As for oil clearance between the cam and bushing, @ 0.001" per inch of diameter is a pretty safe bet. I think my clearance was somewhere @ 0.0015", cam OD is like 1.3" diameter.

I've got a pretty good system down, having had.that one done already I know what works or what I would change next time.

I would not indicate off the advancer housing hole. Just give me a call...I'll walk you through exactly what I did, then you can figure out what works best for you.

[BarnBoy]

Got the frame all fixed for the 82 atc200 (no letter). Glad to get that done...I still need to find a good seat pan. If anyone has one let me know.







Still working on my TIG welding but happy with the result.

Hopefully I'll be back working on the 200M as soon as I get a few parts in.

[kb0nly]

I just did some measuring tonight, my angle plate wasn't large enough, will have to dig up a larger one, this project is not a huge rush, it might take me months to work through this one. I also did some measuring and it looks like the advancer opening is not as concentric to the bore of the cam as i was hoping, my cam surface is completely trashed on this one so there is no measuring from it, so i got the probe out and put a good cam bushing in and bolted on the rocker cover with the four allen head bolts, just as a quick test with it all held in the vise, and yeah i can probe off the rear cam bushing and center the DRO from there and work off that with more precision. Hadn't really given it a lot of thought until i started looking closer at the issue.

I was planning on pinning the cam bushing like the rear cam bushing is, so we are on the same page there, i was thinking interference fit and a pin to keep it from spinning. Might not be until February before i get back to this now, i just picked up some other paying jobs that will keep me away from the hobby stuff for a while!

[BarnBoy]

I just did some measuring tonight, my angle plate wasn't large enough, will have to dig up a larger one, this project is not a huge rush, it might take me months to work through this one. I also did some measuring and it looks like the advancer opening is not as concentric to the bore of the cam as i was hoping, my cam surface is completely trashed on this one so there is no measuring from it, so i got the probe out and put a good cam bushing in and bolted on the rocker cover with the four allen head bolts, just as a quick test with it all held in the vise, and yeah i can probe off the rear cam bushing and center the DRO from there and work off that with more precision. Hadn't really given it a lot of thought until i started looking closer at the issue.

I was planning on pinning the cam bushing like the rear cam bushing is, so we are on the same page there, i was thinking interference fit and a pin to keep it from spinning. Might not be until February before i get back to this now, i just picked up some other paying jobs that will keep me away from the hobby stuff for a while!

Well you saw my setup on the other thread right? I bolted the rocker cover to the head and to the angle plate with some long bolts. Take care to not scar the head gasket surface if you have it bolted together NOT on the angle plate. Keep in mind the the engine will be assembled using RTV or preferably yamabond etc to seal the valve cover. Apply the gasket maker to the surfaces before you bolt it together. You want EVERYTHING to be the same as it will be once its running.

Next, buy a new rear cam bushing. They are still available @ $25 NOS. Then you have a perfect hole to indicate off of, and its not worn at all. May need to get an indicator with a longer snout, whatever to reach down in there. I wouldnt trust anything other than that bushing to locate off of. Now, you still need to be at exactly 90° to the spindle and concentric on the bore. You could accomplish this by indicating off the big bearing hole as well as the small one, but obviously thats not an accurate method. You'll have to get creative, I forget what exactly we did but you may have to find a straight edge somewhere, use gage blocks and sweep it in, whatever you need to do. Once you make your first cut you'll have a surface you can indicate off of to see how close you are to concentric. You'll just have to mess with it, lot of setup time but the job itself isn't anything special.

Hope it helps, any other questions you know how to reach me..

[kb0nly]

I was just thinking i should buy a new cam bushing to indicate off of.... We are on the same page, i got ideas how to do it. I have lots of indicators, a long arm one that should work, electronic probes, etc. Indicating in hasn't been a huge challenge for me on projects. Still learning on the milling side, running a lathe i'm more experienced, but a lot of learned methods apply.

Worst case scenario, i screw up a destroyed head and rocker cover that was headed for the scrap bucket so its a fun why not try project!

[BarnBoy]

I was just thinking i should buy a new cam bushing to indicate off of.... We are on the same page, i got ideas how to do it. I have lots of indicators, a long arm one that should work, electronic probes, etc. Indicating in hasn't been a huge challenge for me on projects. Still learning on the milling side, running a lathe i'm more experienced, but a lot of learned methods apply.

Worst case scenario, i screw up a destroyed head and rocker cover that was headed for the scrap bucket so its a fun why not try project!

That's what I would do. Buy a right angle fixture plate, square it up on the bed. Then use a gage block and indicate across the advancer hole to square the head angularly. Center up off the lower bushing and make some chips. Please post pics of your setup/process and finished product. I dont have all the pics from when I did it, but if you document yours it will help people down the road.

On the topic of the 200M build, I got my material in yesterday for my bearing carrier. Hoping to start on that soon, should be pretty simple...just bore both ends for the bearings and seals, then make a center spacer. Will post pics as I progress.

[BarnBoy]

Right now I'm waiting on basically some free time to start making the bearing carrier for my 200M.

I've been piddling off and on making plugs for the 200M motor, so I can keep it water tight and power wash the paint off it.

[DSHOT59]

Good to see another one saved. Great job on that frame man, looks sweet.

[BarnBoy]

So finally got some time to work on the rear bearing carrier. Got the body turned, next step is to measure and make or modify my existing spacer. Then design and cut the disc brake bracket. Gonna be sweeeet.

[BarnBoy]

More progress. The mounts were plasma cut, and the threaded portion I turned a slug on the lathe. Centered and TIG welded, then drilled and tapped on the mill. Works much better than trying to weld a nut or pre-threaded slug onto a part because the heat always warps and distorts the piece. But if it's a solid slug you get a perfect hole. Threaded M12x1.25 just like from the factory. Super happy with how it's turning out so far.

[MrConcdid]

This man has skills.
MrC.
It's looking great.

[Dirtcrasher]

This man has skills.
MrC.
It's looking great.

Yup, he's making some great stuff. Things that I couldn't do back then without equipment. I told Lane that he's spoiled now, he'll never be able to fix anything without a TIG, lathe and a mill