Scooterotica

soosh wrote:Whats it going in though? If its a standard ish spec, £140 for a forged piston seems ott.

Stage 4 barrel, 26 delly big bore clubman and a cyclone so looking for performance..

Depends on the exhaust port width (and shape) of the Stg IV or you could end up with a ring breaker. A decent width and shape than the standard Mahle would be fine. However, some people will go too wide for this piston on their Stg IV tune, based on the fact that they tune it for a piston with better rings (more flexibility and less likely to break when bowing in and out of a less supporting wide port).

If we are really talking about a SIL factory IV then most pistons will cope, however, any further tuning (incl. many dealer tunes) must use pistons with better rings.

Adam

soosh wrote:

Muttley McLadd wrote:

soosh wrote:Where did the rebore after a 1000mls come from too?

Rapido barrel??

Are they that bad? I looked into buying one yrs ago before i got this kit.

Think it's just the race version that tends to be a bit of a sod with pistons and the exhaust port.I know a few with the classic version or a tuned version of the classic,using a smaller exhaust port,with no issues. I believe they are a bit tight off the shelf and need honing/boring to give a safe clearance of piston to bore. They seem to perform well,but the 1000 mile running in period seems tedious.Not sure if that alters though when they have been fettled or not to be honest.Cheers,Speedy.

Mahle 2 x 1.5 ring, £48. They should go smaller than 66.6. Rayspeed stock them poss 66.2 or 66.4 smaller bore means cheaper rebore and more of them left for future use. If they're good enough for Ralph, then they're good enough.

Correct !!.. If not, then A.F.do oversize asso pistons too.. good quality and not overpriced!! ..if you must pay more

However, do note that Ralph made a point of specifying the Mahle 3 ring piston (only using top 2 rings), rather than the Asso thin ring. That said, I'm not sure that the Mahle thin ring pistons were available at the time.

I've, as have plenty of pals, fitted and made good use of the Mahle thin ring pistons from AF (and probably others too). Indeed, this is now my piston of choice for most mild tunes.

Adam

ive done two iron barrels one with a reed valve using the scooterrestorations sr200 piston..the biggest is 67mm and have wire rings and are a whopping £35