AV10 walkin' cranks. Anyone else?

Jonathan Feldman /

Alright, I'm on my third AV10. Airsal 50cc with all the fixins. It's not a mega ripper by any means but it definitely has some pep in it's step. Runs cool / no insane issues.

Anyway, I got maybe 120 miles on it and I'm already getting crank walk. I definitely think it's the crank bearings shifting back 'n forth in the cases. Maybe .5mm cold and 2mm-3mm when its pipin' hot. Word on the street is that crank walk isn't the end of the world but I'm also bummed that I'm gettin' it so early in the game. Like I'm not even at 500 miles, ya feel me?

I'm rockin' the cheapo treats AV10 cases. This is second one that I've had walk. The other one lasted maybe 500 miles and yes it was a different cheapo AV10 case. Anyone got any bright ideas? Anyone else havin' this problem? Bearing retaining compound? Add some shims to the bottom end? Maybe buy some fancy pants OEM AV10 cases?

Talk to me y'all.

Re: AV10 walkin' cranks. Anyone else?

Take it apart first and see for sure if it's bearing walk or crank walk.

If it's bearing to case walk, its either poorly machined cases or your installation.

If it's crank to bearing walk, it's probably the crank is just worn on the bearing placement spots, poor installation could cause this too.

First find out what happened.(edited)

Re: AV10 walkin' cranks. Anyone else?

Jonathan Feldman /

> JBOT Admin Wrote:

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

> Take it apart first and see for sure if it's bearing walk or crank walk.

>

> If it's bearing to case walk, its either poorly machines cases or your

> installation.

>

> If it's crank to bearing walk, it's probably the crank is just worn on

> the bearing placement spots, poor installation could cause this too.

>

> First find out what happened.

Banger reply as usual dawg.

You're definitely backing my poorly machined case hypothesis.

Re: AV10 walkin' cranks. Anyone else?

Possibly.

How do you rebuild?

Was this the same crank as before?

Re: AV10 walkin' cranks. Anyone else?

Jonathan Feldman /

> JBOT Admin Wrote:

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

> Possibly.

>

> How do you rebuild?

>

> Was this the same crank as before?

Different crank as well.

Bearings heated then tapped onto crank. Wait till shit cools. MAP gas the cases and plot it all together. Never had a binding issue.

Re: AV10 walkin' cranks. Anyone else?

Should be ok, but here's my thoughts

You shouldn't be able to walk bearings in the cases if everything is cut right. When the cases are assembled, the bearings should get basic real close to dead ended into the end of the machined race in the case. If, when you put your bearings on, the space between the furthest out edge of the cases is too large and the pressfit tolerance is a little to spacey, then this is what happens. Next time do lots of measuring and shimming or get better cases.

Re: AV10 walkin' cranks. Anyone else?

Ana L. of the Aurora Roras /

Microwave the bearings for 1:30 wrapped in a damp towel. :)

Re: AV10 walkin' cranks. Anyone else?

The guy on two stroke stuffing has his bearings slip fit with no interference, ca. just put them on with his hands. Kinda cool, then you just add shims until it doesn't walk anymore. But still, I dunno why you would have 2-3mm of play in the crank any direction. Seems dangerous...

Re: AV10 walkin' cranks. Anyone else?

Ana L. of the Aurora Roras /
97C2C0FF-7695-4AD7-8BA7-54C9EB2AFDDF.jpeg

I’d try to fit a large wavy in the case on 1 side to stabilize the end play.

Re: AV10 walkin' cranks. Anyone else?

Ana L. of the Aurora Roras /
93B5EFF2-DA07-44B7-8909-1B9F988CBE04.jpeg

It needs to press the outside edge.

F469F4D7-D7D3-4F59-8DF9-55F8B6E9A6A5.jpeg

This one I have Fits a 6203 bearing. Find the one that fits ur size. It’s .5mm thick, 4mm waves that squashes by hand down to 2mm.

E587E1E6-5159-4F70-9F39-40BB2C8FF195.jpeg

Put it on 1 side or the other.

Re: AV10 walkin' cranks. Anyone else?

Ana L. of the Aurora Roras /

It smashes completely flat too. That would fix the .5- 3mm fluctuations.

73FEACFC-B504-48DB-9ADA-1525C6F81082.jpeg

If the bearings are good fitting and the crank is floating, put a small spring washer between the bearing and crank. Collared around the shaft, touching only the inside ring of the bearing. That’ll take up the slack.

Re: AV10 walkin' cranks. Anyone else?

Jonathan Feldman /

> Moore Burns & Payne Crematorium Wrote:

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

> It smashes completely flat too. That would fix the .5- 3mm fluctuations.

>

> If the bearings are good fitting and the crank is floating, put a small

> spring washer between the bearing and crank. Collared around the shaft,

> touching only the inside ring of the bearing. That’ll take up the slack.

Wow that was an excellent write up. You are one of the few people on mopedarmy that give me hope for the future of mopeds. Lemme mentally process this and report back.

Re: AV10 walkin' cranks. Anyone else?

You can buy proper crank shims for av10 from mir35. They come in packs with different thicknesses in .1mm increments.

If you take it apart dremel out some trashed bearings so you can slide them on and off and take some measurements and figure out how much shimming you need. Then you can play around with different shims and slip fit bearings every time you build an engine.

There are still some super late oem mbk51 cases floating around out there that cost about the same as the rsm or teknix cases if you find out the ones you have are machined wrong.

Re: AV10 walkin' cranks. Anyone else?

Ana L. of the Aurora Roras /

Right oN good luck! google images, one of them shows how to measure it.

95AB75DE-E312-4C77-AD28-6E61FCFA807E.jpeg
« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account