RM 125 A flat tracker

[Dono113]

Boys got a 125 A I use just for flat track, now this was a quick bike and just before I got it it had a new piston put in.( 57mm Wiseco pro-lite 89 yz 125 single ring) I was going to get rid of it but Nifty talked me out of it(I bought it off him)  we got on methanol now and still it's not as quick as it used to be ( all beit to rider) but stock 125's seem to be leaving on the straight. It's got DG head GMC pipe, Nifty was rounding up 250's on her before the freshen up and I'm thinking it's something to do with the piston?? any help would be much appericated

[cyclegod]

Is the piston a flat top?

[Dono113]

Nope dome cyclegod, Nifty and were discussing it last last night and came up with going back to double ring thought I might be losing compression through the stroke

[Freakshow]

whats the squish and how much comp in there.  meth only burns out at 12 + maybe the piston has changed things.  start your maths fromt here

[smed]

What was the old piston? An 89 YZ one or an RM one?

[Dono113]

Original RM, to my knowledge, that why I want go back

[jimg1au]

meth only burns out at 12 +

this is not true my cr250 runs methanol my cz400 runs methanol and also my tt500 runs methanol
NONE HAVE 12+ COMP
JIM
i know some people experimented with fuels on there crs 73/74 125s and 250s petrol ones go just as fast the meth ones get the jump at the start and out of corners.
that said 1 cr125 1977 one i know off is as farst as 250s it runs meth.
it has taken me 12 months (due to lack of track time) to get my cz400 sorted almost there.
all i can tell you is PLUG CHOP PLUG CHOP PLUG CHOP. you will get it right if the motor is in good condition.

[Dono113]

After much research and development rebore time, new piston and rings needed on hunt for 57.50mm pitson kit now. The yz piston turned out to be 3mm shorter and had a flatter top on her...

[Freakshow]

meth only burns out at 12 +
this is not true my cr250 runs methanol my cz400 runs methanol and also my tt500 runs methanol
NONE HAVE 12+ COMP
JIM
i know some people experimented with fuels on there crs 73/74 125s and 250s petrol ones go just as fast the meth ones get the jump at the start and out of corners.
that said 1 cr125 1977 one i know off is as farst as 250s it runs meth.
it has taken me 12 months (due to lack of track time) to get my cz400 sorted almost there.
all i can tell you is PLUG CHOP PLUG CHOP PLUG CHOP. you will get it right if the motor is in good condition.

sorry let me clarify that then, it may "burn" but unless your 12+ your just wasting your time.  Your giving away all its horsepower, you may as well save yourself all the trouble with meth and run it on plain old pump gas............. Seriously