hey all. trying to get some more info on tuning the mikuni carb on my 2000 fxdl. at high way speeds with the throttle goin from half open to 3/4 or more open, it stutters, which is a lean setting. what is the best way to tune it? the website offers very little info on how to do it properly. thanks for any and all help!

 

Trial and error. Frustration. Then pay someone to dyno tune it. Worth every penny. After messing with mine for weeks I let a pro do it.

 

Unlike the stock CV carb, the Mikuni has a lot more adjustment and there isn't the same small number of jets that work.

I too gave up with the "recommended" jetting and trying to adjust it by feel. I bought and used a wideband O2 meter. The jetting I ended up with was nothing at all like I had to start with.

If you you don't want the hassle of buying and using your own O2 meter then I strongly suggest getting it dyno tuned.

 

Ok thanks for the dyno info. I was hoping it was something that i could essentially zero out, and retune it, but it seems like that is a no go.

 

Try increasing accelerator pump duration, if that makes it better your Main Jet is too lean.

Increase main jet size and retune your AP duration.

 

its lean , you already know that, step up the main jet, try it out. if its still lean, step up again.

 

From my understanding of the mikuni the main jet regulates fuel flow at mostly wide open throttle. Try changing the position of the clip on the needle first. The thing about them with four different fuel circuts really fine tuning can be a pain. After my 5th or sixth time changing jets and the needle I just let a pro dyno it. Case closed for me.

 

Mine has a serious flat spot at 3500 when I smack it hard too. Gonna have to try this accelerator pump. When I am cruising there is no issue.