Which ZA50 Crankshaft? Help!

Hi Folks, want to order a new crankshaft for ZA50 rebuild. Treats says 9.5mm clutch bell ID = V1 small, 10.5mm clutch bell ID=V2 large. Mine is 10mm right on the nose!? Which is right, or is there a third variation?

Help is appreciated!

Re: Which ZA50 Crankshaft? Help!

get the big one. If your paranoid which is good, ive messed this up before. measure your bearing in the side cover, inside diam.

Re: Which ZA50 Crankshaft? Help!

Get your crank rebuilt instead.

Re: Which ZA50 Crankshaft? Help!

Probably Fred /

> Daniel '' Wrote:

> -------------------------------------------------------

> Get your crank rebuilt instead.

In total agreement if the seal sealing surface is not pitted badly on your old crank get a new conrod pressed in your crank for the larger style treats crank does not have a flat side on the brass end bushing that goes into the clutch bell and then in clutch cover, the flat side acts like a oil pump,

Also the diameter of the brass end bushing is a bit smaller than the stock size bushing making for too much play/slop in the bell making for more vibration at high rpm’s,

Why they made the bushing completely round like the small diameter one in older Za50 engines that was prone to spinning off and failure don’t know why, that’s why puch re-designed to larger bushing with the flat side which was more durable and again spread the oil all around like a pump through the holes, (edited)

Re: Which ZA50 Crankshaft? Help!

Thanks for the advice. This particular one is pretty rough. But I have two other motors to dig into. They are both running, so more reticent to disassemble. Was hoping to use this spare as a rebuild but its not as nice shape as I had hoped and was missing ignition bits and the first gear roller bearings and retainer. Seems there are different size retainers too, so I'm not even sure what to order for this particular motor. The little metal roller retainer clips are all bent up as well. :-(

Buying all the odd parts starts to add up quick. Almost better off finding another decent moped and taking a chance on it for parts. Can never quite trust old bearings though.

Re: Which ZA50 Crankshaft? Help!

> Daniel '' Wrote:

> -------------------------------------------------------

> Get your crank rebuilt instead.

Who does rebuilds? I'm thinking of having someone do the entire engine. Recommendations appreciated.

Lee

Re: Which ZA50 Crankshaft? Help!

Probably Fred /

> Lee Snover Wrote:

> -------------------------------------------------------

> > Daniel '' Wrote:

>

> > -------------------------------------------------------

>

> > Get your crank rebuilt instead.

>

> Who does rebuilds? I'm thinking of having someone do the entire

> engine. Recommendations appreciated.

>

> Lee

Many shops and people do rebuilds but none are tested, Best way to do a za50 rebuild is to test it every step of the way during the rebuild process,

What I do it is to set the crank in cases shimmed perfectly without any transmission parts in it,

(this could take a few times because even with measuring tools after you screw cases together with gasket the crank could little bit looser in bearings than the measuring tool shows you because it only contacts two little spots so many times you have to remove bearing and add another 10 or 20 thou shim under bearing on the magneto side to eliminate any side play), (possible to be too tight also), make sure seals are lubed with 2t oil,

Then mount the bottom end on a bike, install a known good stock top end, carb and stock quiet exhaust and ignition, rope start, belt start on the flywheel run it and listen for bearing noises,

Just a full carburetor of gas oil mixture and maybe 1-2 feet of line full of gas oil mixture is enough to run it for a few minutes so no tank is needed,

Check both seals for air leaks, smooth operation while running making sure everything is perfect then install the transmission,

You do not need a transmission to run engine because the crank bearings are lubed by the crankcase/Carter,

If everything sounds good and a smooth operation then install the transmission shimming correctly and then run it some more making sure everything is nice and quiet, no leaks then connect chain and drive train making sure starter clutch is adjusted correctly

If you just take a supposed rebuild engine and slap it on your bike will be hard to isolate any noises, you won’t know if it’s coming from the chain/sprocket, you won’t know if it’s coming from the transmission or crank whatever, you won’t really know if your internal seal is leaking/other things leaking

You won’t be able to know if there was too much side play in the crank or too little and may make you take engine apart all the way down to the crank if the crank wasn’t installed perfect to begin with,

Getting a good rebuilt engine is a 30/70% Proposition if not tested but doing it like the way I just described you’ll have a good running engine that will last for years,

Re: Which ZA50 Crankshaft? Help!

OK, so basically you are running the motor with no trans. Seems funny to refer to as top and bottom as the tranny is on the side. LOL.

I have two Maxis. One runs and sounds pretty good. The other runs OK, but it makes a lot of noise. I'm guessing it is bearings, because I changed the pucks and and tranny fluid. Whoever had it treated it bad. It was like mud coming out. So, if I'm going to mess with it, I want to do everything it needs.

The other one was better taken care of, even though it's two years older. I purchased a Pulini kit for it. Debating whether to tear it down first, or just give the kit a try as is, as it seems decent and I'm not looking to beat on it. Some folks suggested the stock cranks were not up to snuff, which is why I was aiming for a treats "upgraded" crank. Though I'm not quite sure what they actually upgrade.

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