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didnt want to ask here but jetting. VM34s (not asking)
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Author:  COOPS [ Sat Sep 16, 2017 1:30 am ]
Post subject:  didnt want to ask here but jetting. VM34s (not asking)
Looks like my jetting is going to be so far out of whack from the norm from what i have gathered to be normal.
Before i started i expected something like 230 mains with P6 needle jet. 40 pilot. But no way.
Firstly its mild/medium ported/ walms chambers, higher compression, squish band sorted and running on AVGAS. Ive read avgas will make it rich but not this rich!!
Trying to run it in and jet it at the same time. :?
Started with 250 mains,P6 needle jet 35 pilots (standard vm34 pilots) way too lean on pilots and way way too rich everywhere else. (wouldnt even accelerate) just 4 stroking.
At that stage the only mains i had were 220-260 and a set of 150.
So tried some 150s briefly just for education. And it went real good, bloody good. Just burbled below 1/4. Scared its too lean,
So got more jets and tried 220 mains/ needle clip 2nd from top. way too rich everywhere, 4 stroking, hopeless
Then tried 190 mains, needle clip at the top. Better mid, still rich, scared to really rev it because i am supposed to be running it in.
I think i might need some O series needle jets (leaner).3.0 cutaway (leaner), 45 pilots (richer)
And of course a big bag of money.
So far i have bought 30 main jets, 3 extra needle jets 6 extra pilot jets.
looks like i will need 6 more needle jets and maybe 3 slides.
I am not really looking for an answer here. its just a thing i have to go through. not that bothered about the bottom end. (its a race bike)
Its a pain i am in a hurry and hard on the pocket. Jets are expensive here. and it still runs like a bag of shite. :lol:
Oh well, see yuz.
Author:  Hawaii-Mike [ Sat Sep 16, 2017 1:35 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
In case you haven't looked at this: https://docs.google.com/spreadsheets/d/ ... edit#gid=0
Author:  COOPS [ Sat Sep 16, 2017 3:17 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
Hawaii-Mike wrote:
In case you haven't looked at this: https://docs.google.com/spreadsheets/d/ ... edit#gid=0

I have looked many times........ they are all way off!!
Author:  mraxl [ Sat Sep 16, 2017 4:40 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
I'd suggest you start jetting with idle, then mid, and leave mains for last. Air screw will tell you what pilot to run.
Author:  Ja-Moo [ Sat Sep 16, 2017 9:41 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
Yes, put in your biggest mains and tune low and middle first. Just get up to 3/4 throttle good, then work the mains.
PS av gas is not really recommended.
Author:  demus [ Sat Sep 16, 2017 9:58 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
Be careful to not exceed the 3/4 throttle mark to much while jetting the low end.
I had problems with my hamfisted ways and fouling plugs trying to do it that way.
Author:  67lotus49 [ Sat Sep 16, 2017 10:15 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
I have been jetting my 72 H2 the last few weeks. It can get expensive buying Mikuni brass. I have ported FBG cylinders and heads that have the squish
modified. Bike had Q6 needle jets and 6FJ6 needles to start with. Factor in that I live at 6000ft too. I bought P-4's P-2's P-0's for NJ's. Also bought
5 sets of needles 6DH3's, 6DH4's, 6Dh7's, 6DH8's, and 6DP1's. I have main jets from 190 to 250 already on hand. Also have 2.5 and 3.5 slides.

After 2 full days I have it very close. 6DH4/1 with P-0 NJ, 230 mains, 42.5 pilots, 2.5 slides, and airscrew 1 1/2 out.Make sure you mark your throttle so
you know what circuit your in. Also really helps when you use a little starter lever to see it the problem is rich or lean. Also I have to run the crap
91 octane that they call gas here in Ca.

Found this chart that gives the diameter of needle jets that helps to choose NJ Jet needle combo.
Author:  Hawaii-Mike [ Sat Sep 16, 2017 7:02 pm ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
I find this page very helpful: http://kawtriple.com/mraxl/carb/mikunineedle.html
Author:  COOPS [ Fri Sep 29, 2017 2:36 am ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
So, i am getting close now. not perfect but close enough to race next weekend. Need to do another plug chop tomorrow.
45 pilots 1/2 turn out on air screw. 6DH4/1 (top) needle/clip. O-0 needle jet. 230 mains (to lean) will end up with 240-250.
Interesting bit is the rich pilot and superlean needle jet. And my needle clip is at the top. I have fatter needles to try but i dont really need to bother as it pulls like a teenage schoolboy all the way. Much quicker than my standard H1 and better bottom end. So i just have to sort the mains and GO.
Author:  Ja-Moo [ Fri Sep 29, 2017 12:33 pm ]
Post subject:  Re: didnt want to ask here but jetting. VM34s (not asking)
your pilot is way too big, but good to be safe on the track.
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