Jetting Cubs

[BanTech]

Hello guys I am looking for help with jetting. I have a mikuni TM34 carbx2 on a Banshee stock crank (Cheetah Cub cylinders). This is my current jetting:

 

Starter Jet: Stock

Pilot Jet: 35 (VM22/210)

Air Screw: 1 3/4 turns out

Needle Jet: P-8 (389)

Jet Needle: Stock on the First Clip from top

Main Jet: 310

Timing: +4

Cylinder pressure: 180psi

Fuel: VP c-12

Elevation: sea level to 1000ft

 

Its running ok now but I feel that my midrange is still a little rich although the Jet needle is all the way down in the carb on the first clip position from top. I have tried leaning out the Needle Jet from Q2-389 to P8-389 but its still rich . My main jet 310 is perfect at top end. Any suggestions on how do I lean out my midrange? Maybe a leaner Needle Jet or Jet Needle ? or should I lean them out both?

 

Appreciate your Help.

[Ducman]

I would try some P6 needle jets and set the clip to about the middle position. I run the P8's in my TM34's but I have been told that they are still a pretty rich needle jet for most banshee applications. I run the TM 34's on my 4mm dune port stroker. I run 35 pilots, air screws 2.0 turns out, P8 needle jet orafice, and 310 mains, rocket pipes, pod filters, +6 timing, 145psi w/ 18cc stroker domes, about 300-400ft (at home) elevation, 100 octane. When I ride near my house the P8 needle jets are pretty good with the stock needle that came new with the carbs on the 2nd clip from the blunt end. I have the actual needle # written down somewhere if you need it to verify you have the same one. When I go over 2000ft they get noticeably richer, too rich. But recently when I dropped them to the first clip from the blunt end (leanest needle setting) and ran it at sea level and 50 deg F it was way too lean. It leaned it out enough to cause some detonation on 100 octane that I usually run w/ no problems. Didn't blow my motor but on inspection had F'ed up both my pistons enough so that they need to be replaced. So my motor is definitely in the P8 needle jet range, but your cub cylinders are a lot different, not to mention the stock stroke.

[BanTech]

Thanks for the response. I think I will do that and try to lean out the needle jet. I will buy P-6 and P-4 just in case. I will start with the clip on the middle position and see how it will ride. I do a lot of dune riding, I need the power to open up when I either hold the clutch and giving it and letting go of the clutch or by just giving it WOT and I supposed to get the power gradually to climb the dunes . Anyway thanks Ducman and I will keep the forum posted.

[rocketboy]

i had the worst luck with jetting my Tm 34mm on my she ,i eventually sold them and switched to keihin pwks and everything is good now

[Ducman]

The only hard part I had is with the needle jet orafice,getting the correct one. Lucky for me, I got some good advice from the place I got the carbs and got it right the first time, but when I first put the carbs on and ran it, it sucked. After I got the right needle jets, getting the needle position right was pretty easy, although recently I second guessed myself and it screwed me. Didn't realize I was so close detonating and that a lean needle could do it. The pilot and main have both been a piece of cake to tune.