Mikuni VM26 Round Slide Jetting Equivalence?

[fastplastic]

if you convert 45 and 125 to your jets it will move but will be a lil on the lean side JUST A SUGGESTION

[Wheelman-111]

Greetings:

Your post wasn't clear to me. Do you think I need something close to 45 pilot? The 32 idled warm at 225, but the engine revved just a little on small throttle openings, dying Completely opening more. Too small pilot AND too much Main? What's your carb? What jets? On what engine? That's all I'm asking, not a guarantee I won't grenade.

[fastplastic]

Im running a 72 ported contessa with a 28mm kehin and my jets be 45 125 im staying convert these jets to the mk size and your bike should run... if you convert a mk jet from 160 to a kehin i belive the chart says that is a 190 size im thinking your main is very rich and your poilt is a lil small if i understand what you r posting....

[fastplastic]

Any luck?

[Wheelman-111]

Greetings:

Just finished screwing in 45. The biggest pilot Treats carries is a 50, and this is only a 72cc, so it sounds really big. However, the idle air screw ended up at 1.5 turns out, so maybe it's the right call.

Problem is my smallest Mik Main except for one is 155, indexed at 1.16mm, and with that fitted, it refused more than 1/8 throttle and lost RPM just after clutch engaged at 6k. Couldn't ride more than 50 feet.

So I figured the mix goes too rich for combustion as soon as the Main starts to come online. So the main's too big, right? The plug was black, a bit oily, a hint of double-dark brown, maybe. Sure not lean by any stretch fo' sho'.

Now for that "except one"; had an old 90 hex for some reason. I drilled it to 1.04mm, not being able to access Mouse's handy Table, figuring about 10% smaller. (Someone will correct Wheel-maff) and tried it. It seemed no better.

The carb's included jet needle is thick and little taper; only have the one.

I have Proper Mik jets down to 110 on the way, planning to try 130 or ?? When they arrive. Also have 47.5 and 50 pilots soon, but feel 45 is enough.

Thanks for axting Fast, I don't feel so lonesome. ALL input is welcome at this point. If a small Main doesn't make the jump to WarpSpeed, I'm ready to give up and get a keihin PW26.

[fastplastic]

I wouldnt give up but the kehin/oko is a little bit more of a comfortable place lol plus with the needle with a rich main put the clip on the top rung of the needle if u haven't tried it....

[Wheelman-111]

Greetings:

Yes I did try full-lean needle and really not a lot of difference.
If Mouse's tables are correct, I need like a 110 or 115 to match the jet flow size, but of course all depends on the carb it's in.

The VM came fitted with 60/190, so maybe it was meant for a 500 single. Sheesh!

[Wheelman-111]

Greetings:

Mains from 110 to 150 came in from Treats, along with 47.5 and 50.
If Conventional Wisdom is correct, the problem isn't my Pilot because max idle speed comes with the Air screw precisely 1.5 turns out.
It just DIES right off the throttle however. Makes me wonder if there's a problem with my assembly or a missing part someplace. I'll try 125 and see if I can even make it to the Casa Gates.

[Wheelman-111]

Greetings:

This will end testing on the VM26 Mikuni for now. See sad scooter saga under Flash 3.26QM; R.I.P.

[LMH]

I have the VM24ss for the 04 4 stroke Yamaha ttr125 with a bbr150 kit on it, I run a 17.5 pilot and a 97.5 main if that helps any. I just started tuning it and it seems pretty close as for now. Heres a link to thumpertalk about the carb tuning if itll help any. http://www.thumpertalk.com/topic/746915 ... -it-works/
In my opinion about double the displacement of a 2 stroke is like the equivalent of a 4 stroke. So say a 72cc 2t is much similar to jetting on a 150 4t, Ive found it to be pretty close if not dead on. It sounds like youre going too rich to me, but then again its a 26 and not a 24.

[LMH]

Also on a side note my 06 Kaw KLR650 has a Keihen CVK 32, I run a 142 main and 40 pilot, so those jets you have are pretty much for a very large engine you got with the carb.

[Wheelman-111]

Greetings:

Thanks for the input, dawgs. It seems it was just about to run with the 50/180, but that's another story. (See General Discussion.)
Moving the needle clip up or down didn't make much difference, but one place you don't want to put it is in the intake tract...