2005 rm125 jetting....

[Dirt Addict]

In checking fmf vs p/c websites, fmf recommends a 440 mj, 40 pj and stock needle.  PC recommends a 370 mj, 40 pj.
Why such a discrepancy in the main jets?
Don't they generally do the dyno testing corrected for temp and elevation?  I know dyno's will vary, but I would think they would be closer.....
Anyone have a good baseline for their 05 rm125?  I will be running mine from 800' to 3000' asl,  temps from 60 to 80 f.

[2T Institute]

What's Suzuki recommend?  I would say you will make a better spread of power with the standard pipe. If you converted it to 115mm conrod with a GP piston would be a truely awesome bike. They are a very very good bike.

[beaner]

FMF recommends a 390 main for the 04+ bike. The 440 is for the earlier bike, different carb.

I am using the same as what FMF recommends for my 04 at 800 ft. Been set up like that for 5 years.

[Dirt Addict]

What's Suzuki recommend?  I would say you will make a better spread of power with the standard pipe. If you converted it to 115mm conrod with a GP piston would be a truely awesome bike. They are a very very good bike.

Pipe? I'm talking about jetting... I just picked this up and I'm going thru it to get it set up as a practice bike for mx.  What does the 115mm conrod do?  I ordered the gp piston.

thanks for the replies. I'm gonna look at the websites again....

[2T Institute]

What the engine wants which is most important.
115mm conrod does a few things, best is there is less rod angularity, that means a lot to me  To you it will mean less wear on the piston,less friction and more dynamic compression. The longer rod dwells at TDC longer and is slower down to 90 deg ATDC.Faster from BDC to TDC which suck reeds open faster. Difficult to explain but basicaly means you get a wider flatter torque curve, which makes the bike easier to ride fast.

Send me a PM and I'll show you where to get the other bits and pieces for the conversion.