2003 CR125 Jetting help

Greetings forum members. I just got some questions that I cant seem to get answered so I thought Id ask here. So currently I'm running a 405 main a 30 pj and needle on third clip. The needle is also not stock. It was a different taper than stock that I bought because the bike manual recommended that for my elevation. Anyways, I dont remember exactly what that needle was called but I can find it if you need me to. Anyways, I live in Lake Tahoe California and Im at around 6,200 feet with riding temps around 40-80 degrees. Currently Im running the jetting that the manual recommened with the stock Mikuni carb. So heres my issue: up top it seems to screem pretty well with good power but down low it doesnt seem to have any snap. I know the 125's dont have much for bottom end but it just doesn't want to rev which makes me think its jetting. If im coming into a corner and drop to idle then give a big whack of the throttle and drop the clutch, instead of going BRAAAP it just kinda sounds like it can't quite get there as if off-idle to mid-range power is just not there. Im also running vforce reeds with stock header and a turbine core 2. Im thinking of gettin a shorty to maybe boost my bottom end? Anyways what do you guys think I should do? Leaner? Richer? On the pilot? Or on the needle? Thanks!

You should definitely jet it right, which is going to be hard because the mikuni tmx's are very temperamental. Took me a while to get my cr125 dialed in but its a whole lot better when it is. Also, check what the gearing is (sprockets). You should be running stock or possibly 3 teeth higher in the back or 1 lower in the front.

 

I've found with the tmx you really need to have the perfect balance of pilot, needle clip, and main, but once you get it set up right it really responds well. I also put an 05+ air boot on my bike which made a huge difference in throttle response. The newer boot has more volume for an air starved motor.

 

Edit: And these CR's REALLY have no bottom end, your gonna have to abuse the clutch in corners no matter what.

Edited by dan2581

You should definitely jet it right, which is going to be hard because the mikuni tmx's are very temperamental. Took me a while to get my cr125 dialed in but its a whole lot better when it is. Also, check what the gearing is (sprockets). You should be running stock or possibly 3 teeth higher in the back or 1 lower in the front.

 

I've found with the tmx you really need to have the perfect balance of pilot, needle clip, and main, but once you get it set up right it really responds well. I also put an 05+ air boot on my bike which made a huge difference in throttle response. The newer boot has more volume for an air starved motor.

 

Edit: And these CR's REALLY have no bottom end, your gonna have to abuse the clutch in corners no matter what.

Okay Thanks a lot man

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