MOPED ARMY

I'm still a little bit confused as to weather it's binding when you put the two case halves together or only after you put the transmission cover on.

IF it only binds when you put the trans cover on, it's either #3 or #7.

IF it binds when you assemble the case halves and nothing else, it's #1, 2, 4, 5, or 6.

Either way, here are the possibilities:

1. You shimmed your races incorrectly, causing your crankshaft bearings to bind.

2. You didn't press the outer races the correct depth into the case halves.

3. Your over-enthusiasm with the FORTY TON press bent your new crank, putting a bind on it.

4. You're assembling the case halves in a vertical orientation like this = instead of vertical (as if they were on the bike). Sometimes if you assemble the case halves the wrong way the bearings won't be centered on the races and will bind.

5. Your starter clutch is out of adjustment with the new crank.

6. Your 2nd gear clutch is binding on the crankshaft after tightening the clutch retaining nut. This can be checked if you tighten the nut and then check to see if the 2nd gear clutch spins freely. If this is the problem, let me know and I'll expand on it.

7. Your trans cover shims are incorrect.

Ok, I know exactly what your issues are. First, after your starter clutch you have the spring, c-clip, a shim, and then the metal starter plate, correct? Now, do the splines of the metal starter plate extend above the shoulder on the crank?

My guess is yes, and if so you have to either have the splined part of the starter plate lathed down below the shoulder on the crank or do it carefully with a belt sander, etc.

After you have that done, put the 2nd gear clutch on the crank along with the starter plate and the spacer between 1st and 2nd gear clutches. The spacer should sit down on the crankshaft shoulder that is now above the splines. If there is a gap between the spacer and the shoulder (which there probably is), the 2nd gear clutch must be modified by turning down the 3 cheeks.

If you want pictures, let me know. I can pull apart a motor or just highlight the stuff on factory drawings.

Nope. The spacer shouldn't need to be modified. In fact, I wouldn't modify it or it might break.

I've had to do stuff like this with all 5 aftermarket ZA crankshafts I have installed so far. It makes me think that having a needle bearing connecting rod pressed into a stock crank would be a easier solution...

Ok, I want to repost some pictures so you are 100% confident before you start removing material... check back in a jiffy.

Just to make sure. When you have the crank in the case and the two halves bolted together your end play is in spec correct? and the crank spins by hand?

awesome, that is what I was thinking, thanks for the pics they help show it better.

why would I give up, when It is the right way to fix this the crank was machined wrong to begin with so the transmission parts need to be corrected to compensate for it, fifteen is cheap but with the price of shipping a whole engine out not worth it/ my stock crank was bent on the flywheel nut threads.....

Tammie,

The thin shims that go between the inner races and crankshaft cheeks may or may not be necessary. You can measure the dimension and compare it to the shop manual spec to see if you need shims, but the races should always be pressed on until they stop; shims or not. If you're feeling lucky I guess you can just skip the shims on that part, but it's better to do it right.

I've found that you don't really need to heat or cool either part down, just use a tube with the right ID and a hammer or press.

If you're doing new bearings, replace the races that are pressed into the crank too. The new races that came with the bearings are matched to the shiny new bearings. The races can be a real pain to get out though. Some of them can just be punched out with a slender punch, others have to be cut to release pressure first. It may also help if you put the case in the oven for a while and then punch the race out. The aluminum expands faster/more than the steel race.

I just did a ZA50 stuffed crank in a rebuild and no shims were needed.

It was a stuffed crank from Treats. I pressed the bearings on and everything is in spec. No shims were needed. I did it about a month ago.

I went to napa and got some plasti gauge, made checking endfloat approximately 1 bagillion times easier..........

Oh and tammiecat, I would not worry about your shimming the crank yet it should stay almost the same. I replaced the bearings and did not run into shimming issues with that, just the crank being off in milling because I bought the race one from 1977.

I ended up doing what you said. It was very hard to measure but it appeared that the spot on the crank that the spacer between the clutches sits on was roughly 1mm off from where it should have been. I had my crank shimmed so that my endfloat was correct but I was still sitting above that lip or whatever it is called do I then shimmed my flywheel side to try and compensate and there was no way of getting it to sit level with the splined piece so I just ended up grinding it down. When I measured it against my stock crank it was somewhat smaller but it was a big enough gap that it was not able to be compensated by shimming.

yeah same

It might of been the bearing brand you used.

I wouldn't run that needle bearing in that wrist pin unless you like siezing the little end of the rod. Very poor qc. buy ina bearing for it..