RM 125A & TS125R pistons Do NOT Mix

[Husabergpete]

Recent experiment by a dealer/on seller of bikes has proved that the special RM125 A pistons can not be mixed with TS 125 R pistons - reason is the RM piston has a crown and the TS R is completely flat which had a very negative result on the compression of the little 125 mot-O-cross-ar. No compression resulted in a pig to ride. Fix was to put it back to Spec........

[huskibul]

    I think there's a bloke in brisbane that mod's the heads on A's to suit those pistons, give's you a bigger range of oversize's ? maybe some power gains?

[reg]

Thats spooky Husabergpete, i've got exactly the same problem, bike may have come
from the same builder .

[Davey Crocket]

I can fix that....we mod the head to get back the compression.....and because its a modern design combustion chamber we make, you end up with a higher compression =better, faster engine that burns the feul more complete....win win. BTW,Im the guy in Brisbane. PM me if your interested, cheers John.

[reg]

Thanks John, will keep that in mind, i should have a new piston next week.

[NSR]

John, does that also apply to the N/T model?

[Davey Crocket]

The problem with the 125A Noel is geniune only supplied std/1st and second oversizes and 125's are hungry for pistons and with alot of owners "good" aircleaner maintenance, 35 year old engines, most of them are just plain worn out....going to the TSR125 piston gives a few more bore sizes, but being a flat top you need to put the compression back in....N/T's have 4 bore sizes and a few aftermarket piston suppliers so more life. Having said that, any old  engine would benefit from a modern combustion chamber....and as our fuel quality/octane starts going down the gurglar, most guys will have to do these mods to run on the shite fuel.   

[oldfart]

 quote .... "and 125's are hungry for pistons'.
You are spot on there.

[Lozza]

The VERY best 125 engines still run domed pistons. A good option is to Nicasil over tha cast iron back to the standard size. Economicaly very good as there are tons of stock sized pistons out there, you can also use modern 125 pistons as well.