I have a pal that raced a 01 cr125 totally stock,pipe,silencer,everything in 05. He got top 3 starts sometimes and won alot, ended up 1st in Northern Cup series, that was highly contested, ave. 30 or so in 125b. He,s 6 ft. 1 or 2 175 or so. I have a 04 cr125 and 2 months ago picked up a 06 cr125. The 04 is slower than the 01 stock,until jm racing ported it and borred the carb to 40 mm, it pulls a YZ 144 on hills with a 35 lb. lighter rider on the yz. If your going nuts and want to mod your bike a little get the rad valve, take it apart polish the internals, on my 06 it made an instant diff. On my 04 before the porting, I installed the vforce and was disapointed,very little diff. On my 04 my engine guy endorses FMF, I told him I hv. a PC on it,whats the diff.anyway he said the fmf hits harder, the mod motor hits hard already, the pc pipe has better over rev. On a hard pack track I took the pc silencer off, put the stock silencer on with the pc pipe, it was smoother delivery,lost top end. It really comes down to riding as much as you can, or if you only have time for 20 laps, brake late smooth in threw and out of the corners, be precise everywhere, be aggressive on every inch on the track, then every mm, no cruising. Maintain your bike, if you want to become a really great 125 rider, have a practise 125. What you want on a 125 is a smooth flow, with your wheels on the ground it feels like your flying, in and out of corners it will feel like your in the air,because your so dam smooth.
