Well the RM is responding well to mods, it has a better engine than the mags give it credit for, the fisrt thing to note is its almost a exact clone of the KTM top end, the only thing they failed to copy well is the pv flap-it only drops a few mm into the cylinder where the KTMs drops a full 12mm i seem to remember.Apart from that its the same.
From the initial testing i can tell you a few things about the new rm, the silencer on the rm is a small core design-i thought this would hold the engine back, however with testing i found both the 2C pipe and HGS used a small diameter pipe from the stinger, this is used to make good top end power, so when i added the HGS silencer i shouldnt have been surprised when it added no power.We tried a 4mm spacer on the 2C pipe to try to get even more bottom but it just killed the overrev.
Both the 2C front pipe and the HGS added power, the 2C adding more.The std pipe is a nice dyno curve but can be easily beat. The HGS created a huge dip when the PV opened.We found by opening the pv by hand at 8000rpm it removed the dip completely.So the rm governor spring is too stiff and some preload needs to be removed, im going to try 0.2mm less preload.The difference from best to worst of the dip is 4hp, and its right at the point where you need it most on a 125 as you try to exit the corners.So for almost nothing you can make a big gain in power.
The ICAT added no power-see products review forum thread.
My jetting wasnt far off,
37.5 pilot-was too lean needs a 40 or 42.5.
needle middle clip-ok
main 430 ok
We did mod the head for a closer squish(std 1.3mm) modded to 1-1.1mm but looking at the graph i dont feel this added power.
If you want more top end then its down the the exhaust port height-you could easily raise it 1mm and you should suffer a small loss in bottom for a good gain in top and overrev.
Last we tried 2mm advance timing for more bottom but again it just lost overrev, then we tried 2mm retard timing and we made gains from mid up so i left it there, at this point the bike was getting a bit hot and bothered and not making as much power as it could have due to heat, we had no more time to let it cool and start a new run.
The best run was about 34.5hp which equates to about 39hp on the fmf dyno :laugh:
So what dynos do you want to see
we have the ICAT ones posted, and the 2C pipe is in eric forum.
I will put up the exhaust test for now
2C pipe is red, HGS is blue and std is green