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Wossner piston in RB20?

Posted: Mon Feb 11, 2019 4:08 pm
by Stoink
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I bought a 65.5mm wossner piston from a German supplier. When I went to install it I noticed the ring pegs are over the open sections of the intake port. This is in my opinion not correct. I asked the supplier what is going on and was told that's how they are run. Is this correct? It looks very concerning to me. I included a picture . The red marks are the location of the ring pegs

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 5:00 pm
by mick1
i'm fitting a Wossner into my Avanti. I took the barrel to AF and they checked the pegs would miss all the ports...........they seemed to think it was quite important.

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 6:05 pm
by Scooterdude
Best course of action speak to Ben at AF, he’ll put you right straight away, best to ring him after 5.

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 6:07 pm
by Scooterdude
Can you compare with your old piston? Were abouts are the ring pegs on that?

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 6:34 pm
by Stoink
I bought the unused kit without a piston. Just thought I'd ask here before bothering rayspeed. Seems to be a common conversion. I did a search here but it doesn't seem to have been a topic. Logic tells me the shop I bought from is trying to pull the wool over my eyes. Thanks for the help!

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 6:53 pm
by mick1
You can always move the peg positions yourself, if pushed.

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 7:51 pm
by Scooterdude
Piston clearance looks a little on the large side have you tried it?

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 8:12 pm
by Stoink
I would leave it to a professional to re peg it, if it comes to that. Not sure who reliably does that. Can't seem to find one stateside. Might be cheaper just to call rayspeed, ask them about it and order the correct piston depending on what they say. The measurement of the piston to cylinder clearance is 0.002.

Re: Wossner piston in RB20?

Posted: Mon Feb 11, 2019 8:31 pm
by Scooterdude
Stoink wrote: Mon Feb 11, 2019 8:12 pm I would leave it to a professional to re peg it, if it comes to that. Not sure who reliably does that. Can't seem to find one stateside. Might be cheaper just to call rayspeed, ask them about it and order the correct piston depending on what they say. The measurement of the piston to cylinder clearance is 0.002.
Bang on that mate.

Re: Wossner piston in RB20?

Posted: Tue Feb 12, 2019 9:47 pm
by gaz_powell
I've just changed a Mitaka Yamaha DT piston in a lined TS1 for a Wossner Yam IT175. The DT pegs went though ports, despite several people saying it would be fine after chamfering the edges, i couldn't live with it .
The IT pegs now sit in the barrel and not the ports.
What piston is it for Yamaha ?
The IT I'm using has the peg positions further apart and i would say they would be outside the ports.