34mm mikuni vm carb jetting

[maskmanLS6]

Im trying to figure out where to start with jetting a set of 34mm mikuni vm carbs. Im swithching from a set of stock carbs with 330 mains 30 pilots and fmf needles in the middle clip. I have a stock stroke stock cylinder engine with an aggressive dune port and V force reeds. My 34mm carbs currenly have 25 pilots and 260 main jet, The needle jet is a 159 p-4 and the needles are 6DP1 , Any help with this would be greatly appriciated.

[RadarRacing]

That is very close on jetting those for a banshee. Usually like 250-280s.

[maskmanLS6]

That is very close on jetting those for a banshee. Usually like 250-280s.

 

Thanks for the info, will be riding some this weekend to try them out. I hope they give a decent gain in power.

[RadarRacing]

If its modded any you will see a couple hp over stock. Ported with a high rpm pipe, vforces, pod filters etc you may see like 4-6 hp over stock carbs. Those are the stock carbs on polaris 400s and I have used them a couple times on banshees with good results.

[maskmanLS6]

If its modded any you will see a couple hp over stock. Ported with a high rpm pipe, vforces, pod filters etc you may see like 4-6 hp over stock carbs. Those are the stock carbs on polaris 400s and I have used them a couple times on banshees with good results.

 

Cool, Im hopin for a decent gain after putting the money into those carbs. 6hp would be a gain i could actually feel and thats what im after. I have some good port work, Fatty pipes and vforce reeds. Im hoping for around 60 to 65 hp with all of it,,I weigh around 200lbs and need the extra ponies to keep up with my sons banshee.

[Yury888]

I bought a banshee with mikuni 34s. It runs good, but after 2hrs ride starts bogging. I was thinkin its plugs fouled. They were wet. Then I decided to check jetting. I was thinkin it runs rich. But i found 45 and 150!!! Jets in it. So it means it was running lean? I was thinking it was bogging because of rich, but 150 jets made me confused. I tried 290 - bad, no powerband and no power. 250 - better, but powerband bogs. 210 - very good. Powerband hits stronger than it was on 150. 

Question is why my jetting 150-210 is so low, if people say that 200 is stock jetting?

I have coolheads and pipes. Have no idea on internals, compression is 120, starts easy.

Also I think I need to go lower on pilot jet.

 

 

Edited March 7, 2023 by Yury888

[Yury888]

Also there are big foam filters on each carb and no filterbox. I was expecting jetting 250+ based on reading forums.

[Yury888]

My guess is that someone has jetted Mikuni as Keihin. Keihin jets are close to 50 and 150-160. So I will stick main around 210, and try go low on pilot from 45 to 25. It smokes too much on idle and beginning of acceleration.

Edited March 9, 2023 by Yury888

[Yury888]

Went from 45/150 to 25/210 and it runs much better. Main jet 210+ bogs, 210 is fine.