Jetting for 310 kit

[mattcruff]

I just ordered a 310 sleeve kit from LA Sleeve. It was running a little lean when i melted my piston due to cooling issues. I have a 140 jet in my carb. What do you guys think would be a good starting point for the 310 kit? Like i said the 140 was a little lean. It was bored .040 over. Has a FMF Fatty pipe and silencer. Im guessing its the stock carb. The serial number on it starts with 37. It may be a 37mm?? Will i need a bigger carb? Or can i just jet this one correctly? LA Sleeve's website says i can run the stock carb.

[mattcruff]

Come on guys. I don't know where to start. I dont even know if i need a bigger carb.

[Saul]

Jet really fat and work your way back. No need to risk seizing a new piston right?

So go with the fattest jet - at WOT is should stumble/blubber - keep working back one size at a time until all the 'stumble' is gone and it's super crisp at WOT then go 1 size larger on the main just to be safe.

Before you start jetting make sure to check and re-check all other factors which can influence your final jetting.

New plug properly gapped.
New or VERY clean airfilter.
Leaks anywhere - intake, gaskets etc etc
Your planned fuel/oil mix ratio that you will run.

But again, run it fat initially and work your way back.

[1BFC]

Well, I have the same cylinder setup as you have. I also have the same exhaust. My carb is a PWK 38 or 39mm Air Stryker though. I also run 225psi compression and 100LL for fuel (aviation fuel). Plug gap at 0.15. K&N filter with the air box lid OFF and stock intake boot to the carb.

Jetting is very very machine specific. Here's what I am running currently though.

Main jet: 178
Slow jet: 48

It'll run with a 170 but it's on the hairy edge with that jet in it.

Billy seems to think that my cylinder is ported (it came with my bike, I didn't do it) so you may consider that as well.

Personally, after having Billy help me with mine and learning it first hand I think you are going to just have to do it yourself. You just can't go by others results, they can only get you started. If you seized with a 140 on a stock cylinder, I'd start with a 185 and work from there. Do the plug chop and cut the threads off to read it. That's what Billy and I did and it worked perfect.

Better safe than sorry...185 is probably too high. Rather be wrong that way!

btw, it's totally amazing how much of a difference just a single jet size makes. The difference between "just under the blubber" and "spot on" is tremendous.

Good luck!

[mattcruff]

Alright sounds pretty good, Ill just buy pretty much every jet between 190 and 150 and see if that wont work, i guess at the least i will have alot of extra jets for my other trikes.