Bing to Mukuni jetting

[skiracer]

If one were to switch from a Bing to a Mukuni carb, is there a conversion chart for the jetting, or do they both use the same numbering system?

[tomale]

skiracer, no they don't use the same numbers but you might be able to find what others are running by checking old posts. use the search button on the top right hand corner.
what size bike are you working on?

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
72'sixday (project bike)

[skiracer]

Hey Thom,

The bike is a 76 250 MC5.  Thanks, James

[tomale]

well that makes it easy, this is what I have been running in my bike, I made the switch several years ago and I was amazed at how well it improved the overall performance. This is what I am running, I am running a 34 mikuni that was professional bored out to the specs of a 36, the reason is that it is a smaller body and gives me more room. but I set up my buddies HS with a stock 36 mikuni and it worked but it was a really tight fit. here is the specs; 290 main, 30 pilot, 2.5 slide, 6dh4 needle (middle notch) and a 159 Q2 needlejet(if you use a 36 mikuni that Needle jet will read. 166 Q2 this is based off basically sea level
I found the Mikuni extremely easy to jet. better to start a bit rich and go lean.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)

[skiracer]

Thanks Thom!

Does it matter what model the carb is, or are all 36mm,s the same.  The one I have has a shaft that you pull up for the choke instead of a lever that moves up and down.  I will see what jets are in the carb now, and adjust to your numbers.  Thanks again!  James

[Merlin]

Just to let those reading this know, the #166 series needle jets are for 38mm Mikuni. The reason it was used in the application above is because the 34mm body was bored to 36 and the lower shoulder profile of the #166 series was required to get the shoulder out of the airflow of the bore. For 30-36mm Mikuni's the #159 series with the taller shoulder is the proper needle jet.

Quote: Thomas Jefferson, We are all born ignorant, some work to remain that way.
 Quote:Peter Villacaro, "it is impossible to teach those that wish not to be taught".

[skiracer]

I hate to assume things, so, on the main jet, as the numbers get larger, is the mixture getting richer or leaner? Thanks, James

[tomale]

Yes,as the numbers get larger the richer the mixture. Mikuni makes a manual that includes the round slide carbs I have found it to be very useful.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)