Puch ZA50 vibrates

ZA50 engine w/ Polini 64cc with 650+ miles on the kit.

It was a smooth ride until just recently. Now it vibrates at higher speeds and when decelerating. I feel it in my feet on my pedals and in my hands. I used to be able to see out of my mirror, now it vibrates too much. I think it gets a bit worse as the bike warms up.

I recently changed my transmission fluid and the bike was running amazing for a few days, but now it started the high intensity fast and steady vibrating (and I think it sounds a bit louder too?). This is my 2nd Puch and it definitely doesn't feel normal.

The reason I mention the transmission fluid is because there's some strange instructions on this page that I may have misread:


It says to overfill your trans fluid your fluid by 50%. I used about 11oz of Valvoline MERCON V (DEXRON III) ATF. But no matter how good my seal was, it would leak out the side level plug. So I looked at that link again and at the end of the paragraph, it says "DO NOT FILL the trans with too much fluid, it will cause too much crankcase pressure and could cause your seals to leak." Is it just me, or are those instructions contradictory? How much should I really be putting in?

I unscrewed the level plug, made sure the bike was level, and let some drain out the level hole until it stopped, so I assume it's now at 9.5oz as described on this page:


The level plug doesn't leak anymore, but if anything, the vibrating might be a little worse.

1. Tightened the engine mount bolts. No change.

2. Tightened my drive chain. No change. I loosened it back to where it was.

3. Messed with my idle speed and choke. No change.

4. My air filter is kinda crappy and seems to be getting some gas on it. I ordered a better one from treats and it should be here in a couple days.

5. My bing carb is brand new but I've had it open a few times to adjust it and I'm worried I need new gaskets? It's a little leaky. Or perhaps I adjusted it wrong.

Could the bad air filter or leaky/improperly adjusted carb be the source of my vibrations? Or did I do something wrong with the transmission?

Re: Puch ZA50 vibrates

The same thing happens to the e50 w/ 72cc Airsal kit on my Magnum, especially when decelerating so I'm hoping someone will chime in.

It's totally fine when I'm riding at a good clip but if I come to a stop light or slow down by laying off the throttle, my engine vibrates and makes a slight "clickity-clack" sound until I speed back up.

Re: Puch ZA50 vibrates

That sounds much different than my vibration. Mine does it while accelerating and riding too.

Re: Puch ZA50 vibrates

Overpriced Parts /

I run 0w20 synthetic motor oil overfilled to 12 oz in all of my puch z50 trans

Way better then type f protects the clutches, gears better overall, way better protection then junk type f, better clutch slip and take off too.

Could be your your clutches are coming apart or splines excessive wear if your geared much lower then 21x36 and then of course you're running just no protection type f made for stock engine 35 years ago fluid not new state-of-the-art oils they have nowadays.

Re: Puch ZA50 vibrates

Thanks for the tips, perhaps I should try that.

I have # 25 and 30 springs and both clutches are flipped.

Re: Puch ZA50 vibrates

Overpriced Parts /

Dave Earl Wrote:


> Thanks for the tips, perhaps I should try that.

> I have # 25 and 30 springs and both clutches are

> flipped.

Why both clutches?

Re: Puch ZA50 vibrates

Ken Roff Wrote:


> Why both clutches?

That's the way I bought it and it ran nice so I haven't touched it. I suppose it should be just the 2nd one flipped?

Also, I'm in L.A. California, so should I get a thicker oil than 0w20 for the hot climate here?

Thanks again!

Re: Puch ZA50 vibrates

If you guys are running stock cranks, I've seen many bushing cranks vibrate exactly like that at higher RPMs and still run without any noise or knocking... after a while it just gets worse... Basically big-end rod failure...I really ran one so long that it only knocked when the spark-plug was removed while spinning the motor over but when the plug was in it ran without any knocking....but, had a bad vibration at higher RPMs so I just took it easy on it until I rebuilt it...I drove it that way for like a year and just babied it...that shows you just how tough Puch ZA-50s are...

Re: Puch ZA50 vibrates

I changed out the trans oil with 12 oz of 10w30 Royal Purple. I did alot of research and everyone's opinion differs on what oil to use, but it seems more people recommend 10w30 than anything else. Plus I wanted something for hot SoCal temperatures.

It did seem to help a bit, it might run a little smoother, and there's no leak out of the level plug, but the vibration is still there and mostly after the bike warms up.

My new air filter treat should be here tomorrow and I'll put that on. Then I'll check for any other air leaks anywhere and see how that goes. Sometimes the vibrating is worse than other times so I'm still hoping that carb/air problems might be the cause.

If it still vibrates then I'll pop open the trans and try flipping the 1st gear back. It sometimes likes to rev up too high before shifting anyways, which might be because both gears are flipped (that's the way it was when I bought it). And I'll inspect the crank and rod. I believe it's a stock crank, so maybe I should replace that anyway. What would I be looking for to know if the rod is going bad? Thanks again!

Re: Puch ZA50 vibrates

Oh-My you should just get it rebuilt or go to an E-50...and the type of oil is making it slip like that...

Re: Puch ZA50 vibrates

Yah, if you aren't running high gear OP your bushing is probably melted. If you didn't put a new crankshaft in or have it rebuilt - it definitely is a bushing up there.

Quit looking in the trans. The only time you get vibration there is clutch engagement and disengagement, not WHILE the engine is running. From your description the vibration doesn't center around shifting or clutch slip, so quit looking there. Takes a lot more than 650 kitted miles to wear out ZA internals if it's built properly.

You can keep pouring money down the drain trying different oils out, but you have a mechanical problem. Pull the top end and inspect the small end bushing. If you don't know how to tell if it's good - READ THE MANUAL.

All your problems likely stem from spinning the ZA too fast - don't confuse that with too hard. ZA's like a lot of power, not a lot of RPM's. The two are not mutually exclusive.

What's your gearing? (edited)

Re: Puch ZA50 vibrates

That sounds logical that it's not my transmission if I have a constant vibration, and not just when it shifts. Thank you. My gearing is 19 x 35

Re: Puch ZA50 vibrates

Bobby Selby Wrote:


> the type of oil is making it slip like that...

Oh, why does almost everyone on these forums recommend some sort of 0w20 to 10w30 on za50s then? And it revved when it had mercon v in it too

Re: Puch ZA50 vibrates

Overpriced Parts /

It works with type f or mercon it just has more clutch fade/fades when hot synthetic motor oil doesn't fade as bad when hot and offers way more protection for the gears in bearings

Flip the first gear clutch back to normal and see if it still does it.

Re: Puch ZA50 vibrates

So I tried all the quick and easy fixes first. I put on the nice new air filter, re-adjusted the carb properly and got a performance spark plug for the hell of it. The bike runs even better now but unfortunately it still vibrates at high RPMs.

I also just found a major air leak where the cylinder meets the exhaust pipe, so I ordered a new gasket from treats, and I'll cross my fingers that it will help. And I'm probably going to send my engine to mopedcrankworks for a needle bearing rod kit.

Tomorrow I'd like to flip the clutch back to stock.

Will I need to re-shim anything if the only thing I do is flip the first clutch back?

Re: Puch ZA50 vibrates

Fixing the air leak was nice but didn't stop the vibrating.

So I popped open my engine to flip the 1st clutch back to stock. Well lo and behold, it was Not flipped as the guy who sold it to me said it was.

Only the 2nd clutch was flipped, as it should be.

But my engine was revving super hard and waiting a really long time before shifting, so I tried flipping that 2nd gear back to stock.

Viola, my revving is gone, I shift great now and I really get better acceleration and overall performance.

Unfortunately, I believe it made my vibrating worse.

There's new pucks and new bearings.

The seller said he didn't re-shim when he flipped the clutch. So I figured if I put it back to stock, I shouldn't touch the shims, and they'd be back to default.

Should I re-shim anyway, and could an incorrect shim be causing the vibrations?

I was hoping to properly shim in a few weeks when I get a performance crankshaft.

But if I need to re-shim, should I stop riding? Like "stop riding right now", or more like "get that taken care of soon when you get your new crankshaft".

Thanks everyone

Re: Puch ZA50 vibrates

Overpriced Parts /

Most times stock shims are fine to put back if you didn't change crank, clutches or gears.

Did you check all your clutch pads to see if they're worn evenly?

Re: Puch ZA50 vibrates

Dirty30 Dillon /

Ken Roff Wrote:


> Most times stock shims are fine to put back if you

> didn't change crank, clutches or gears.

> Did you check all your clutch pads to see if

> they're worn evenly?

If he really did put new springs in, they could be binding. ^^^

Listen to Ken and Ryan.

Re: Puch ZA50 vibrates

The clutches were not worn very evenly. The first clutch had a little chunk out of it.

The copper bushing at the end of my crankshaft rod also has a bit of play in it.

Re: Puch ZA50 vibrates

Overpriced Parts /

Dave Earl Wrote:


> The clutches were not worn very evenly. The first

> clutch had a little chunk out of it.

> The copper bushing at the end of my crankshaft rod

> also has a bit of play in it.

Yep those are your problems

Rebuild to specs

Re: Puch ZA50 vibrates

Thank you Ken. Should I immediately stop riding, or just be gentle on it until I get the new parts?

By the way, I feel the vibration pretty much at all times now at any speed. (edited)

Re: Puch ZA50 vibrates

Overpriced Parts /

Dave Earl Wrote:


> Thank you Ken. Should I immediately stop riding,

> or just be gentle on it until I get the new

> parts?

> By the way, I feel the vibration pretty much at

> all times now at any speed.

That depends I nursed a mild kitted za50 for 2 years with bad bearings but

I had a stock crank on another bike starting to vibrate 2 miles away from my house and I got to my street before it blew and locked up. I had to pick up the back end to get it home .

Half a dozen of one

Six of another.

Bring something to remove the MasterLink if your engine locks up so you could be able to push/peddle it home

Re: Puch ZA50 vibrates

Unfortunately my bike starting a loud knocking now. I just got my paycheck and was about to order the crankshaft too , but now I'm pulling it apart to make sure that's the problem.

It only makes the knocking noise when the bike is moving; It sounds fine at idle or while revving it a little with breaks on. But it does start knocking a bit when I lean the bike forward on its stand and let the back wheel move.

I popped of the cylinder head and it seems to be ok and the piston moves fine. It also makes a small clicking when I roll the bike in reverse. Sounds like it's still the crankshaft?

Re: Puch ZA50 vibrates

Overpriced Parts /

Back and forth play in a crank can be ok but front to back play no not good .

It's hard to say what's wrong with your engine without riding your bike .

Re: Puch ZA50 vibrates

My first discovery....

Where can I get a new one of these? I don't see any on treats or 1977


Re: Puch ZA50 vibrates

I'll post in the buy and sell forum for that first gear. But to be more clear, I was wondering if anyone knows where to get a new one.

It has 70 teeth.

What could have caused this problem, and should I continue to look deeper? (edited)

Re: Puch ZA50 vibrates

Try Myrons Mopeds call Shaun 714-992 5592 PST in Ca., Tu.-Sat. 10- 6 . They have new and used parts.

2nd clutch wiggles

Thanks Steve. I didn't realize Myrons might have new parts, I'll give them a try.

I have quite a bit of play on my 2nd clutch and I'm wondering if that's normal. With my first clutch still on and the nut is torqued, I can reach behind it and wiggle the 2nd clutch back and forth along the crankshaft, almost as if it needs another shim. But I believe I have the cone washer and shim in the proper place on each side of the clutch, as described in the manual and the wiki. Is the 2nd clutch supposed to move?

Re: Puch ZA50 vibrates

Overpriced Parts /

Yes play is correct its supposed to be there but you can shim it so there is no play if you choose to, at least some people made a post about doing that I never did it their way (edited)

Re: Puch ZA50 vibrates

Thanks so much Ken. I've done my best to research, read and learn, and you've been a great help in my long-winded and newbish thread.

I was surprised at how much my bike revved up in first gear when I bought it.

Hindsight is twenty twenty... I shoulda taken it apart immediately. It's just that the bike ran so well otherwise, and fast - up to 55mph, so I didn't touch it until it was too late and it started vibrating..

There was about a half a tooth missing on that first gear when I flipped the clutch back to stock last week. (apparently it started a chain reaction and quickly destroyed the surrounding teeth?) That whole first gear feels rough and worn. But the other main shaft gear isn't worn at all and feels smooth. Do you think that first gear was getting destroyed because of the high RPMs my bike was hitting in first gear (before I flipped my clutch back)?

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