briggs + Mikuni = what jet sizes to start with

[yellowandfast]

I have a warmed up briggs 5hp with ported intake and exhaust, no combustion chamber porting, a 94ss cam, shaved intake tappet, makes about160lbs of compression and will be fed by a 24mm mikuni side jet carb, will also have a stepped header of some kind

The question is about where does a guy start his jetting at? I have never jetted a 5hp, I have jetted dozens of Yamaha 2strokes but those are a completely different animal.

any pointers would be cool

Thanks

 

[125ccCrazy]

first of all what 24mm mikuni do you have? a real VM series or a cheap taper bore?

 

[yellowandfast]

its a vm, not a piece of s*** copy

 

[125ccCrazy]

try it out with factory jetting and read the plug and go from there...if you start changing stuff from factory right off the bat it will be harder to tell what direction you need to go unless you have had the same or simular set up before to go off of as a base....it's pretty much impossible to tell you what you need to run since each engine is different, temp, weight ect ect....

if the fact jet is a 100 and it looks like its pretty lean try a 120, if its still lean go up to a 130,,,, I prefer to go too rich and then lean it down instead of lean, richer, richer richer until its right.... if you have it rich you know to step it down a few but when its lean it takes more jets and longer time to get it right.... makes sense in my head but I may not be wording it so it makes sense..:shrug:

 

[yellowandfast]

there are not any "factory" jets in it to start with

Let me rephrase my question

What jets are commonly used when puting a 22/24mikuni on a 5hp briggs?
pilot and main please


Thanks

 

[5 Horse Fan]

I would say the ones that came with the carb stock......
Mikuni carbs have adjustable venturis instead of throttle plates.
You usually swap the high speed needle for performance engines.

 

[mini fanatic]

24mm carb jetting

the 5 hp is a 200cc ,i am using a 24mm keihin off a 200x honda 3 wheeler,the jet size that came in that one is a 108 main jet and the pilot is a 4 c ,mind you i haven't tried it on my 5hp yet ,still working on and building it right now but it might be a starter point for you.