Best Mikuni Jetting Database

Michael Forrest /

Contribute to this jetting database and get a free evaluation of your jetting in a graph such as you see here. The red graph shows the jetting richness from closed throttle to WOT. Above the horizontal 1.0 line is too rich, and below it is too lean. Every data point needs to be fulfilled. You can make this the best database ever for Mikuni because it is the most complete. Just post your details here and if you want the graph emailed to you in case it looks terrible then just email me at 19jaguar75@gmail.com

bike:

2 stroke or 4 stroke? (2/4):

carb model:

carb size:

idle jet #:

air screw turns out:

needle #:

needle jet ID:

height of needle jet shroud:

(above the base level of the bottom of the venturi. VM 18/22/24/30-36 have one. VM 16/20/26/44 don’t. Leave blank if you don't know and I will use 22% of the carb size)

main jet #:

tried different main jets? (Y/N):

(This tells whether or not the main jet you are using is the most optimal one)

slide cutaway #:

% ethanol in fuel:

elevation:

if 2 stroke does it have a reed valve? (Y/N):

type exhaust pipe? (1/2/3):

1. just header and muffler, no expansion chamber.

2. expansion chamber with straight header

3. expansion chamber with expanding header (edited)

jettinggraph.jpg

Re: Best Mikuni Jetting Database

Michael Forrest /

c'mon Mikuni users, I know you're out there. Post your data here and hopefully it will help someone else in the future.

Re: Best Mikuni Jetting Database

trick question, mikunis don't need jetting, they run perfect just the way they are.

Re: Best Mikuni Jetting Database

Michael Forrest /

not a "trick question" but rather a dumb answer

Re: Best Mikuni Jetting Database

Dirty30 Dillon /

> Graham Motzing Wrote:

> -------------------------------------------------------

> trick question, mikunis don't need jetting, they run perfect just the

> way they are.

It's true. Anyone can plop a VM20 on a moped and ride happily. The single best/worst feature of the VM series

Re: Best Mikuni Jetting Database

Michael Forrest /

Well then that's just showing that the stock jetting for a VM20 is appropriate for a lot of moped engines but it doesn't make Mikuni a "magic" brand by any stretch of the imagination. I started to make my jetting calculator after realizing by trial and error I could never get my VM20 to work right on my 100cc 2 stroke street bike. I had to have in depth analysis of what was going on for me to know how to change it to make it work. It was the worst jetting situation I'd ever had but thanks to it my jetting calculator was born and when I was done with that carb the jetting was spot on the money thru the whole throttle movement and the bike was a joy to ride.

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