Mikuni 22mm Help Needed

[2nd Ranger 75th LRRS]

Finally got my 6.5 Modified Clone started. I am having a fit trying to get this thing to idle properly. I adjust the the screw that lifts the barrel and when it starts it idles high enough to engage the Bully 2 Disk Clutch. The clutch is setup to grab at 3200 rpm. I turn the screw and lower the idle to an acceptable RPM and when the clutch disengages I start adjusting the Air Fuel Screw located on the bottom of the carb next to the Float Bowl and it does not make a change. No intake leaks.
I installed the 12.5 pilot Jet and the 130 Main Jet. I assumed that the .95 Main Jet from the Factory would be too small. Also, everything I have read has indicated that most everyone is using the 12.5 Pilot Jet instead of the factory 15 Pilot Jet

The engine has an ARC Billet Rod, T3 Light Flat Top Piston, 285-0207 Cam, 22cc Head milled .050 and ported with 26lb springs, 27mm 24mm valves, 1.2 Billet Rockers set at .005 each, Billet Alum Flwheel with 8 degree key, Snake 3 Stage Header Pipe.

Any pointers or help on this issue would be greatly appreciated.

Thanks

 

[osso12]

just by the sound of it... if its not making any change when you move the screws you are sucking in too much air. double check your rebuild hoses, etc.

 

[2nd Ranger 75th LRRS]

just by the sound of it... if its not making any change when you move the screws you are sucking in too much air. double check your rebuild hoses, etc.

I removed the carb and checked intake gasket and it is sealing. I am not so sure its a vacumn leak. I have to turn the screw to lift the carb barrel to allow more air in just so it will start. After it starts I can turn down the idle but get no change when I adjust the air fuel screw. All the fuel hoses have a zip tie and I checked those also. I have one hose coming out of the valve cover going to a catch can with 2 ports and the other port in vented to the atmosphere.

If I turn down the idle then it will not start until I turn the screw back in which raises the idle.
It is very responsive and revs up very quickly with no hesitation but I want to set the mixture right so I don't toast the motor.

 

[jonboy]

Should be able to run the fuel screw in until it starts to bog down then back it out about a half turn. If you can run the fuel screw all the way in and have no bog or start to sputter, then the pilot is to big. Try a 10 to see if it helps make the change.

 

[2nd Ranger 75th LRRS]

Should be able to run the fuel screw in until it starts to bog down then back it out about a half turn. If you can run the fuel screw all the way in and have no bog or start to sputter, then the pilot is to big. Try a 10 to see if it helps make the change.

Have you ever heard of someone running a 10 pilot ? This motor is 11.1 comp and I have been reading some of the agk stuff and they run 12.5 and so do most others. I will try it and see what happens. Bad thing is I have to order the pilot since no one around here has them in stock. I live close to Austin Texas. If anyone knows of someone around there who carries them please let me know.

Thanks

 

[2nd Ranger 75th LRRS]

Another question is which way is rich on the screw. Is it in or out ? Mikuni 22mm

 

[osso12]

Another question is which way is rich on the screw. Is it in or out ? Mikuni 22mm

rich should be out... or counter clockwise.. lean would be turning the screw in or clockwise....

 

[qtband]

In is richer.
Where you are located has a lot to do with jet sizes. Humidity as well as altitude. The jets used in Denver would cause an engine to run poorly in Miami.
If you are using a used carb, make sure you clean it well. I'd suggest using the boiling in lemon juice method.
I tried to attach an older pdf on Mikuni carbs. It may give you an insight on the proper jetting for your conditions, however, it's 3.25 megs and I can't upload it. If you want it, PM me your regular email and I'll send it.

 

[2nd Ranger 75th LRRS]

Mikuni 22mm Tuning Issues

Ok. Update on what I found with my Mikuni 22mm.
In the an earlier part of this thread I mentioned that I had to open the slider in order to start the engine and then turn the screw and let the slider fall in its bore to lower the idle. I did this again and shut the engine off. Now all I have to do is depress the gas pedal slightly and it starts just fine. I can turn the air fuel screw and feel some change but not dramatic. I tried reinstalling the #15 Pilot Jet and now I can feel a noticeble change when I get the screw about 1/2 a turn from closed.
This thing wanted more fuel the whole time. I guess the 12.5 Pilot was not enough. It was the idle speed screw that was throwing me off by having to open it to start it. That was telling me it was rich at idle. I still dont think its quite right so I am taking it Tuesday to the Jap Bike shop behind me. They have more experience with the Mikuni Carb than I do. I will tell you what happens when I get it back.

Reaper