Piston has a lot of play on the crank bearing

So I am trying to get my friends moped working right. He has got one of them treats reed kits. The piston has a lot of play on the bearing that connects to the crank. Will this be a major problem? The play is happening where that bushing/bearing goes through the hole on the crank.

Is a new crank in order?

Thanks.

Re: Piston has a lot of play on the crank bearing

Christian Giron /

I had the same problem recently

I was told that side to side play is okay, but a lot of back and forth (up and down? pull and push?) play = bad crank. I think my old one had ~3-4mm play and the one in the spare motor with about 1mm of play was okay according to mattology.

Re: Piston has a lot of play on the crank bearing

yeah its not side to side its forward backward.

Re: Piston has a lot of play on the crank bearing

Christian Giron /

here's some threads I found

https://www.mopedarmy.com/forums/read.php?6,1842320,1842394#msg-1842394

https://www.mopedarmy.com/forums/read.php?6,1850764,1850812#msg-1850812

https://www.mopedarmy.com/forums/read.php?6,1853187,1853295#msg-1853295

https://www.mopedarmy.com/forums/read.php?6,3098179,3098686#msg-3098686

and a quote from grey

"Grey L (saabsonettguy) — Jul 01, 2010 03:27PM

The tomos A3 manual says it should have between 0.2-0.5 mm axial play in the connecting rod. I dont think puch lists it in their manual, but I imagine its probably pretty similar? "

Re: Piston has a lot of play on the crank bearing

Thanks a lot.

Re: Piston has a lot of play on the crank bearing

Seems like he will have to replace his crank. Luckily I already have an extra one.

The ped won't run at all though, not even idle. So I would guess it has other problems? Or will +1mm of play be the culprit?

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