Jetting question, as if there aren't enough...

notsofast

New Member
Jun 18, 2025
6
0
7
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Just finishing a build for my kid and figured I'd ask about a good main jet starting point. Figured stock pilot and middle groove on the needle.

Mild trail port from Ken O'Conner
Bored to 67mm
Stock Stroke
Shaved head
Full FMF fatty with turbinecore 2
Airbox lid off with UNI 2 stage filter
Elevation around 600'
Super cool graphics with one ronnie mac sticker (good for at least 6 or 9 horsepower.

Oh yeah, I'm new here. Hi.
 
I just needed a start point and searching threads has the main all over the place for similar set ups. I am using the stock pilot which, just finishing my first heat, is all you need. Stock is 32.5. I have my needle clip on the 2nd groove but may change that depending on chops. I do mid range chops and wot chops. I am starting my main jet at 280 but have a feeling that will be rich. Once I do the chops (next weekend) I will let you know where I ended up.
 
I just needed a start point and searching threads has the main all over the place for similar set ups. I am using the stock pilot which, just finishing my first heat, is all you need. Stock is 32.5. I have my needle clip on the 2nd groove but may change that depending on chops. I do mid range chops and wot chops. I am starting my main jet at 280 but have a feeling that will be rich. Once I do the chops (next weekend) I will let you know where I ended up.
Yesh lmk plz, i just rebuilt my top end after i cooked my rings, replaced the whole top bc i couldnt find anywhere around here to bore and hone it for me, but i bought a decent top end from some racing place out in cali, it started up fine and idles fine, but it has a bog now and no matter what i do it just changes the bog, so i sprayed tf outta it while it was running with starter fluid and it didnt take off, ima go outside in a second and put a compression test on it to make double sure but it looks like it needs to be rejetted and i dont know what jets this carb had and the screws are stripped to sh*t in it anyway, so ill need a new carb and an idea where to begin with jets
 
Is it stock? What pipe and air filter? If you have a stock pipe on it, and your air box lid is on with the snorkel, Go back to all stock jetting. What state do you live in? Dry hot climate or humid? High elevation? Normal?
 
66mm top end, fmj powercore2 exhaust, stock air box and snorkel, and im about 1480ft, im in south dakota, its humid and hot right now. About 100°
 
66mm top end, fmj powercore2 exhaust, stock air box and snorkel, and im about 1480ft, im in south dakota, its humid and hot right now. About 100°
I just did the compression test, its just over 100psi, id say 105 or so, so thats not great. Not sure what to do about that other than buy a new set of gaskets and take it back apart and do it again i guess
 
I just did the compression test, its just over 100psi, id say 105 or so, so thats not great. Not sure what to do about that other than buy a new set of gaskets and take it back apart and do it again i guess
When i pulled the plug to do the test, it wasnt burnt or real brown looking either, so idk, seems lean..