E50 cranks to pair with a polini

Stefan Josheski /

What crankshafts and bearings have people used for the polini kit with good results? (edited)

Re: E50 cranks to pair with a polini

Dunno specifically about your question. However, I killed some time today reading about crank balancing and found this cute yerterb videah.

Simple little static balance setup. Probably not perfect, but better than nothing. Since you seem like you’re in the market for crank info, I’m going to dump it here.

Re: E50 cranks to pair with a polini

Any needle bearing aftermarket crank will work. Some, if not most, require different shimming to make perfect and I wouldn’t use any of the needle bearings that come with them. Get a good one like a Top brand.

Re: E50 cranks to pair with a polini

Sander Mulder /

> Papa _ Wrote:

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

> Dunno specifically about your question. However, I killed some time

> today reading about crank balancing and found this cute yerterb videah.

>

> Simple little static balance setup. Probably not perfect, but better

> than nothing. Since you seem like you’re in the market for crank info,

> I’m going to dump it here.

>

>

This is NOT GOOD for a puch crank. you have to use a balance factor. In our case, horizontal cylinder it't about 30-40%. this means you have to weight the (half) conrod, pin, needle bearing and piston, take 40% of this, hang that in your crank, then it should not be moving in any position.

back on topic, i have used topracing cranks in my engines without problems, with high hp 70cc kits.

Re: E50 cranks to pair with a polini

Probably Fred /

Rito cranks you can reuse old stock shims most times because circlip grooves are in the right places Unlike super stuffy and others cranks that are off and take slim shim on the one side, most times.

Shimming the crank to clutch, starter clutch and bell is the hardest part of a e50 build.

I did several rebuilds with a rito crank and that part was a breeze but it was awhile back so I don’t know how good the cranks are of as late.

Re: E50 cranks to pair with a polini

Yeah, the guy in the video was putting way too much weight on there. Maybe 100% balance factor works for whatever that goes in, but all my internet research says NO.

I thought the video was funny because that little kid was making engine noises. It does show how simple the task can be done and I imagine most moped folks just buy a crank and toss it into the case with whatever kit; never even considering the potential balance problems.

thanks for the 30-40% info. I was gonna ask at some point if I couldn’t find it elsewhere.

Re: E50 cranks to pair with a polini

Any of them are good. I prefer the stroker. Most of the time I just sand the outer clutch bell circlip down a hair on the treats cranks rather than mess with shimming.

Re: E50 cranks to pair with a polini

Sander Mulder /

> Papa _ Wrote:

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

> Yeah, the guy in the video was putting way too much weight on there.

> Maybe 100% balance factor works for whatever that goes in, but all my

> internet research says NO.

>

> I thought the video was funny because that little kid was making engine

> noises. It does show how simple the task can be done and I imagine most

> moped folks just buy a crank and toss it into the case with whatever

> kit; never even considering the potential balance problems.

>

> thanks for the 30-40% info. I was gonna ask at some point if I couldn’t

> find it elsewhere.

100% would be with the cylinder pointing down.

Re: E50 cranks to pair with a polini

I have only used the rito in my rebuilds. It is inexpensive and does the trick. No hassle with shimming. The only thing was that for the starter plate pin to fit in the hole on the end of the crank I had to file it out a bit. No biggie at all.

Re: E50 cranks to pair with a polini

♣Slew Foot♣ /

I did a rito Conrod on an A3 crank it ripped I counterbalanced the clutch shoes...

Re: E50 cranks to pair with a polini

Stefan Josheski /

Nkw that my big end bearing has went bad and maybe the conrod too, would I be good if I pressed in a rito conrod or top racing

for example instead of buying a new crank or repressing the stock crank back in (if its good)? (edited)

Re: E50 cranks to pair with a polini

https://www.mopedarmy.com/forums/read.php?7,4493745

Will knows his shit, his last post about the rito being a smaller journal... Never heard that before but it's interesting.

I have a rito on the shelf that's outlived a couple kits, and a treats plastic stuffy with the plastic cut out that's been in my polini for over 5k miles. I do buy wiseco small end bearings, as I've had the cheap ones that come with the cheap crank fail.

Re: E50 cranks to pair with a polini

I had a top racing crank last about 15,000+ miles on an honest 50-55 MPH polini that pretty much ran at 40-50 MPH most of its life (lots of county roads and city ripping). The one drawback is a special bearing is needed on one side and if memory serves me right, it’s expensive.

Treats super stuffy cranks and Rito cranks are good too, at least in my experience. Comments in the thread about shimming are accurate.

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