mikuni carb on my flathead Harley EFI & Harley Carb Discuss mikuni carb on my flathead in the Harley Tech & Harley How-to forums; bike runs good just does not run out smoothly. does anyone else run a mikuni on their 45 ? if so what jets are you running? i am going to ...

[1950flatty]

bike runs good just does not run out smoothly. does anyone else run a mikuni on their 45 ? if so what jets are you running? i am going to check timing as well...thanks

[milindh]

Hey Flatty

I'm assuming you're talking about a 42mm or bigger Mikuni. You're going to have a real hard time trying to get a carb that big to run right on your 45. That's way too big for your application. Too big of a carb will cause the air velocity moving thru your carb to be so slow that it won't draw fuel well through its jets. It's just darn near impossible to get the jetting right on a carb that's too big for its application. If for some reason you're bound and determined to stick with the Mikuni you're going to have to do some spark plug readings to figure out the best jetting. Mikuni has a website that tells you step by step how to do that. I just think you'll never end up with a really good running setup.

Also unless you have hogged out the hole in your intake manifold there'll be a lot of restriction there. Not good either. In my opinion you need a smaller carb amigo.

Good Luck

[frisco-rigid]

Mil is correct about butterfly carbs like Keihin, Bendix, S&S,, but Miks are more forgiving because of the slide,, BUT not That forgiving.. Do you want us to guess what size Mik you're running.?