ts 125 piston

[PERM250]

hi all can anyone tell me if ts 125 piston will work in rm 125s?

[oldyzman]

Gday, I have a 125s which was owned by neville shephard he said it has a ts125 piston in it as he could not get the right one, mate that bike has so much top end stick I cant help but wonder if it has altered the port timing, its also really weak down low rpm, only ridden this 125s so i cant judge but i am comparing to yz125e yz125a and yz125c of which i have ridden recently.
OLDYZMAN

[brent j]

From what I  have found and from past experience with a TM125 you can run a TS piston but the skirts need to be cut shorter.

RM125's up to the B model have the same bore as TM/TS125's but I'd also check the location of the piston ring locating pins.

CR125 pistons will also fit but again the skirts need to be cut.

As for the lack of low end power, sounds about right to me. I rode TM Bill's RMS at Conondale (thanks Bill!) and it scared me. Imagine a power band after years of riding Yamaha 500's

Brent

[Lozza]

If you want bottom end(or long piston life) trimming the skirt isn't a great idea. There are far more exciting things to do......................

[cyclegod]

This was discussed in the past, TS125 pistons will fit but need 5mm trimmed from the skirt, RM125A pistons won't as the pin is a larger diameter, find an old wiseco catalog with the old part numbers and troll eBay for NOS pistons up to 2mm oversize as your best bet for the RIGHT piston. Only trim the piston skirt as a LAST resort.

[eno]

My son's TM is TS piston equipped, goes so dang good he can beat me on my 400!
I followed 'the wise one's' advise & left the skirt alone... ... checked the intake timing, needed more so chewed into the floor of the intake port to get it, approx 165 to 170 degrees from faulty memory.
It never loads up, almost idles & starts real good but still makes loads of power, there are more mods possible but I'm running in "if it aint broke don't fix it" mode.

[090]

I put a TC125 piston in my tm125 (dont know if it is the same as rm125a) , same as the others, had to trim the skirt. The TC had more over sizes .

[PERM250]

thanks to every one for the help. now off to ebay to find a 2m over piston

[LWC82PE]

i have 80 or 81 wiseco catalogue