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I'm using a Mikuni vm-34 (34 mm) carb and was wondering what size of jet to use. I have increased my horsepower and thought maybe I should use different size of jet, beings how the jet in there may be sized for stock 45 motor because I got carb from 45 restoration. Anyone with thoughts, experience in this area, could offer some input? Any advice would be appreciated.
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The only way to jet a carb is to run the bike and see what it needs. -
mikuni carbm on '48 45"
hello i run a 34 mikuni round slide on a 45" racer and would be willing to give you my jet spec.
I have a handmade manifiold that removed the linkert flange on the H-D manifold and puts the mikuni rubber manifold right at the very edge of the H-D manifold, to do this the cylinder fins must be grinded down for carb body clearance.
With the adaptor in most kits it puts the carb way out from the H-D manifold, and thats where the tuning problems come in especially if the bike is ridden in real cold weather.
My bike runs very consistant with the mikuni and works very well when compared to the best rebuilt linkert.
and the mikuni is very adjustable with a variety of main and needle jets.
I have tested some different size mikuni carbs, the 34mm is the best. 32mm is to small, the 36mm and 38mm are to big even for a relieved racer.
let me know if you want my spec list.Comment
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I would appreciate if you would share specs. That must be the problem, I have considered that as being a potential reason for bikes performance. It would fall flat between 60 and 65. and when I started changing jets, it just fell flat at different speeds.Comment
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mikuni carbm on '48 45"
hello sorry for the delay, here are the exact jetting spec i use on my WL 45" hot rod, it does have some modifications, but I would think this should work on a stock engine also.
Remember if you are riding in a cold climate, and our manifiold is long, as in a adaptor attached to a stock linkert manifold, you should consider doing the work to build a custom manifold that a mikuni rubber flange manifold will bolt right on to and shorten up the overall length of the manifold to intake port.
34 mikuni roundslide:
main jet: #290
piolet jet: #35
air jet [in venturi hole]: #2.0
needle: #6DH3
needle tube: P-6
slide: 2.5
note: needle and tube are important, slide is to as the number is the size of the angle cut on the air side at bottom.
make sure your choke is operateing correctly and not allowing raw fuel to pass by.
you can order new mikuni jets form a company called "carb parts warehouse" the advertize in cycle news, make sure you are testing with known good jets.
Also i am assumeing you know that your fuel float level is a important part on a mikuni.
hope you get your bike running, a 45" flattie will run very consistant with a properly jetted mikuni.Comment
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