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

[notsofast]

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.

 

[notsofast]

nothing?

 

[ElWero1211]

nothing?

Im trying to figure my jetting out too... was hoping u had already gotten the answers but it doesnt look like it

 

[notsofast]

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.

 

[ElWero1211]

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

 

[notsofast]

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?

 

[ElWero1211]

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°

 

[ElWero1211]

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

 

[ElWero1211]

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..

 

[notsofast]

So if all you have done is swap exhaust but sile the stock lid, You might be 1 size up on the main. 240-250. Remove the snorkel from your airbox lid.
After your heat cycles double check the torque on your head nuts. 20ft lbs.
When you used the compression tester, keep kicking over and over while holding the throttle wide open. Do that until you are 100% sure it doesn't move anymore.

 

[notsofast]

So if all you have done is swap exhaust but sile the stock lid, You might be 1 size up on the main. 240-250. Remove the snorkel from your airbox lid.
After your heat cycles double check the torque on your head nuts. 20ft lbs.
When you used the compression tester, keep kicking over and over while holding the throttle wide open. Do that until you are 100% sure it doesn't move anymore.

And, do a leakdown test. Don't even run it without doing a leakdown.

 

[ElWero1211]

Checked my bolts and re-torqued, and ive done a cpl leak down test sprays with starter fluid around the top and bottom of my cylinder where my gaskets are, didnt take off at all. Im waiting on my tors delete kit from in the mail and i already got a few sizes of jets to try this wknd. We'll see

 

[notsofast]

Yeah, definitely delete the tors. The spray thing is just something to do in a pinch. It doesn't mean you aren't leaking. Buy a leakdown kit on ebay for $30-50 or make one. YouTube has tons of videos on how to leakdown a 2 stroke. Super easy. The spray method is no good. A test kit with soapy water is the way to go.

 

[ElWero1211]

sh*t. Didnt know that. Ok and thanks for the heads up. Yeah this is my first bike and it happens to b a 2 stroke, i didnt know sh*t about how to maintain or work on em and thats why i cooked my first set of rings and had to rebuild it. But when i got this blaster all it did was sit there n leak oil, so we've come a long way since then. Still learning. So thank u