1981 YZ 60 Engine Rebuild Help

[JKLNHDE]

Hello all. I am new to the forum and just purchased a rough but running 1981 YZ 60. I had one as a kid and thought it might be fun to take it all the way down and rebuild / restore it to as new for my young son. Can anyone on the forum recommend an engine rebuilder in Houston, TX? Im mechanically proficient but would rather have someone with experience splitting cases, etc. do the machining and disassembly/assembly.

Also, Ive been searching, but am having problems locating a complete set of plastics. If anyone knows where I can find them please pass that info along I would appreciate it. More to follow. Thanks!

[PlanetMinis.com]

[T-Dub13]

Plastics are very rare for that bike. It shares plastics with the 1980 YZ50 which was made only one year. I've restored a YZ50 and built a YZ60 to ride. Happy to help out any way I can. I don't have any of the 80/81 plastics though.

[JKLNHDE]

T-Dub13

Thanks for the offer to help. I saw a couple of the projects your working on - very cool stuff. Yeah- looks like finding the plastics is gonna take some time and luck. As youve been down this road, any advice on the best way to bring back the yellow on the original tank? Im shooting for the best results possible. Thanks again.

[T-Dub13]

There are plenty of ways to restore plastics, but boring hand work was the best although the longest process I've found. Scrape the first layer off with a NEW razor blade, drawing the blade backwards at a slight angle. Then wet sand with 400, 500, 600, 1500 grit paper. Then you can polish with Mothers Mag and Aluminum Polish or Noxon or most any other metal polish, just do a test spot first. The more aggressive the polish the better. Novus plastic polish is next to useless on HDPE unless you use it as the last step. You can skip a bunch of steps if you just want a good looking rider.

[Luckystar64]

I've heard that you can take a torch to the plastic, and that will bring the color back. I mean heating... NOT melting t! Old S'cool MX does that. --L*64

[JKLNHDE]

A heat gun as well. There are a few Youtube vidoes showing people doing this. Gotta be careful for sure.

[T-Dub13]

Yep, I've done that too. The heat gun works excellent for shining up a rider. I found it can darken the plastic a bit though if you're not careful. If there's any chalky plastic on there from sun fade, you've got to remove that first. That's why I usually end up scraping with a razor blade first.

Back to the thread subject though, you can rebuild the motor pretty easy on your own if you've got a manual (ebay). Bearings and gaskets are still avail and I've heard a KX60 piston will work on a YZ60. Or do what I did and bolt on a YZ80 top end. You can call wiseco and ask if any other pistons will retrofit into that cylinder. Lotsa hard parts are still avail on ebay.

Also, you might want to put an ad in Marks Vintave MX site: VintageMX.US - Preserving Motocross History - Motorcycle Swapmeet Lots of guys there who have parts collecting dust.

[pheej]

Give Andy (713) 334-8030 a call if you need machining work on your motor. Motorcycle, ATV Suspension and Engine Work Does excellent work..

[JKLNHDE]

Encouraging you sent me Andy's number at Metric. I sent him an email yesterday but haven't heard back. I think they may be on vacation for the balance of the month. Yes he does excellent work . Any opinion on whether he might touch a job like this? Thanks .

[pheej]

I'd suggest just dropping by with your motor and tell him what all you need done to it. If he's not available talk to Alex if he's still there and i'm sure he could be of help
as well. I've had him work on my Ducati with the bigbore kit and valve work as well as suspention setup and the work is top notch and price is very reasonable not to
mention turn around time. I don't see any reason as to why he wouldn't provide the service. His shop easily accesible just off of 610 in the heights. I'd also recomend
Billy Weiss if your willing to ship or drive in the Austin area, too bad he's no-longer in Cypress. Give him a try aswell if Metric falls through.

[JKLNHDE]

I'll do that. He's worked on a couple buddies Duc's and did the suspension set up on another's race YZ250. Hes very competent and does some wild stuff. I just hope he would be willing to work on a little 60cc overhaul . I've called half a dozen places around Houston and due to its age nobody is willing to touch it and I want it right hopefully without it costing an arm
and a leg.

[T-Dub13]

It's such an easy motor to build. I can't imagine any mechanic not taking on that job. The hard part will be finding a piston kit and getting someone to bore that small of a cylinder.

[JKLNHDE]

Engines out. A remarkably easy bike to disassemble. I had the whole thing down to a shell in two hours with little more than a basic socket set. Engine and carb will be off to the builder in the next couple of days. If anyone has any specific requests I should make regarding the engine rebuild (performance tips and tricks) please pass them along. Its toast - every gasket and seal leaking.

[T-Dub13]

Do you want to build for performance or a stock build? Even of you're going stock, I'd have the machinist clean up the ports a little and make sure he does a nice chamfer on the port edges.

I could get into some porting tips for that motor... If you're interested.

The only major hang-up I found while building my motor was that the BRAND NEW left side crank seal didn't seal, not even close. Pay attention to every new part going into that motor.

I'd suggest going with Boyesen reeds since I don't trust old fatigued metal ones, which will roach the entire motor if one breaks off. You might have to drop the needle one notch since Boyesens run a little rich in the middle sometimes.

[JKLNHDE]

Progress report: it took quite a bit of work but after fixing several frame issues I got the frame and trees back from powdercoat this week. Frame looks very very nice. Motor is apart and after collecting all the necessary parts, it will go back together this week. The cylinder was already maxed out for a Yamaha piston so I'm going with a 43.50mm Wiseco KX 60 setup as well as doing some port work in the cylinder. Should run and look like a new motor when I'm done . *If anyone knows where I can find an unmolested YZ 60 swingarm please let me know. I'm having a tough time locating one and mine is trashed. Stay tuned....

[T-Dub13]

Looks excellent so-far! You might find a swingarm on ebay, they're usually pretty cheap. Let me know if you're looking for any internal motor parts. And keep us posted!

[hobbeekid]

*if anyone knows where i can find an unmolested yz 60 swingarm please let me know. I'm having a tough time locating one and mine is trashed. Stay tuned....

BAM!!! here you go!!!!Yamaha YZ-60 project

[T-Dub13]

That's a 1981. sweet.

[JKLNHDE]

Ok engines all finished. New bearings, seals, clutch, rod + piston (43.50mm KX60 Wiseco). After hand prepping and painting everything it became evident quickly that paint wouldn't hold up over time so before assembly I powder coated everything but the head. I'm waiting on a few carb parts to arrive and then it's ready to fire . The cylinder had been heavily ported in its past so this bike should scream though I went a little conservative when dremeling the piston window as i was concerned with the skirt getting a little thin. It will probably rev 10k instead of 12-13k as it sits but will last longer. Restoring the tank, plastics and wheels is next.

[T-Dub13]

Nice work on the skirt. That actually looks like a larger window than stock, but maybe smaller than the piston that was in there. It will rev fine. I'm not sure what the top rpms are supposed to be. I measured the YZ80 pipe I'm running and it was built for 10500 - 11000 rpm. That YZ60 will be strong.