Wossner piston in RB20?

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gaz_powell
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Tue Feb 12, 2019 9:51 pm

Just had a look on AF site and RB20 Wossner they are offering appears to the pegs outside the windows on the piston, loads future apart than the red lines you show

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Stoink
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Fri Feb 15, 2019 3:25 pm

That's what I thought. Thanks for the help. I ordered a new piston from rayspeed. I'll post pictures of the new piston in the bore with marked peg location. I will also mention at that time the name of the German supplier who said it's fine to run the pegs running across the ports. They need to take responsibility.

Adam_Winstone
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Fri Feb 15, 2019 4:15 pm

^... In their defence, whilst the consensus it that having the ring ends exposed by a port, this was an issue that used to pop up every now and again in the days of the WCLW in USA doing the Humiliator and Annihilator TS1 conversions that ran an upgraded piston. The piston for this also positioned the peg and ends over the boost port, which people would question regularly, however, WCLW said that it was never an issue on any of the road conversions, nor their race bikes. These kits were known for their reliability and I can only assume that this was related to the port being of limited width, which didn't allow the ends to open and spring into the port (similar concept to rings not bowing into exhaust ports if sufficiently narrow).

It may well be that the German supplier is quite right that the version that they supplied does not cause issue in running but it does go against the generally accepted recommendation/concept, which I might not like to risk if I'd just spent money on a kit.

Glad that you've got it sorted though.

Adam

gaz_powell
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Fri Feb 15, 2019 7:28 pm

The tuner who did mine wasn't worried, but i was so even after chamfering the ports i couldn't rest easy, i ran it in then swapped....i sleep easier now as it's something off the worry list when riding !!

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Stoink
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Sat Feb 16, 2019 2:31 am

I respect your opinions on the subject and agree both the humiliator and annihilator were great kits for the 1990's and they did their best with the very limited choices of piston available at the time. But it is far from the 90's and now a large choice of pistons and kits. Since there is now a piston that fits optimally in an RB 20 and does not locate the pegs over the boost port, it seems rather sloppy to sell a piston with more of a chance (even theoretical ) of causing damage to an expensive kit. If it had been common knowledge, I would have liked to have made the choice myself. Wossner with pegs over boost port, or wossner with pegs against cylinder wall. In short, I dont want to risk it either.

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Stoink
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Sat Feb 16, 2019 2:36 am

It is hard not to feel like some distributors will sell off some older stock they can't get rid of when one finds out there is a better version available when it's not advertised there is even a choice...

Adam_Winstone
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Sat Feb 16, 2019 12:36 pm

^... I agree.

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