First things first: I have read, reread, rereread, and rerereread the Mikuni tuning manual. It was a general manual but it hit all the points for my carb too, I think.
I like to make my posts in a strange format and very long:
thumbsup:
Engine:
Tecumseh HS50 5HP, governor removed, +compression, mild port, 14x3/4" exhaust, modified cam (sans decomp)
Mikuni 22mm, 100 main, 17.5 pilot
What I did:
I rejetted the carb because I wasn't getting enough fuel past ~4800 RPMs and I was cutting out. Plus I had the jet needle clip at the very bottom position and was just barely stoich. Went from a 95 to a 100. I also changed the pilot jet from 15 to 17.5 because I wanted to try to resolve an issue with high idle, caused by lean mixture, or so I was told.
The problem:
Now the thing idles so fast it engages my clutch. To combat this I put the choke lever down and it idles just above what it did before I switched out. The obvious solution would be to switch back, which I will, but I need some tuning advice on top of that.
I am pretty good with the typical vac/pulse/flow jet type B&S carbs and every other normal float carb, but these Mikuni's confuse me a little. There is an emulsion tube adjustment screw on the bottom of the carb on the engine side that I cannot figure out for the life of me. I figured out the slide adjustment screw that moves the slide up and down to control idle but I have it backed all the way out so the slide is all the way down.
TL;DR: Rejetted (pilot jet) carb and now it idles super high, still.
My questions:
-How do I get the thing to idle as low as possible, even with the 15 pilot jet?
-Is a lean condition causing the high idle? It idles lower when I take air away (choke). No vac leaks, verified.
-How does the emulsion tube screw adjustment work? I see no changes when I move it in or out.
-If you guys are running M22's, what size jets, what clip position, and what size engines of course?
Other than the idle problem, this carb is flat out insane. It picks up where the old carb left off and it pushes my engine to the point where it actually scares me. Just when I thought I was done accelerating, I'm not. My top speed so far is 48MPH with a 4.6:1 GR. Going up to a 105 main tomorrow to hit 50, I hope.
And sorry if any of that just sounds plain stupid. I just like to get all the information in.
I like to make my posts in a strange format and very long:
thumbsup:
Engine:
Tecumseh HS50 5HP, governor removed, +compression, mild port, 14x3/4" exhaust, modified cam (sans decomp)
Mikuni 22mm, 100 main, 17.5 pilot
What I did:
I rejetted the carb because I wasn't getting enough fuel past ~4800 RPMs and I was cutting out. Plus I had the jet needle clip at the very bottom position and was just barely stoich. Went from a 95 to a 100. I also changed the pilot jet from 15 to 17.5 because I wanted to try to resolve an issue with high idle, caused by lean mixture, or so I was told.
The problem:
Now the thing idles so fast it engages my clutch. To combat this I put the choke lever down and it idles just above what it did before I switched out. The obvious solution would be to switch back, which I will, but I need some tuning advice on top of that.
I am pretty good with the typical vac/pulse/flow jet type B&S carbs and every other normal float carb, but these Mikuni's confuse me a little. There is an emulsion tube adjustment screw on the bottom of the carb on the engine side that I cannot figure out for the life of me. I figured out the slide adjustment screw that moves the slide up and down to control idle but I have it backed all the way out so the slide is all the way down.
TL;DR: Rejetted (pilot jet) carb and now it idles super high, still.
My questions:
-How do I get the thing to idle as low as possible, even with the 15 pilot jet?
-Is a lean condition causing the high idle? It idles lower when I take air away (choke). No vac leaks, verified.
-How does the emulsion tube screw adjustment work? I see no changes when I move it in or out.
-If you guys are running M22's, what size jets, what clip position, and what size engines of course?
Other than the idle problem, this carb is flat out insane. It picks up where the old carb left off and it pushes my engine to the point where it actually scares me. Just when I thought I was done accelerating, I'm not. My top speed so far is 48MPH with a 4.6:1 GR. Going up to a 105 main tomorrow to hit 50, I hope.
And sorry if any of that just sounds plain stupid. I just like to get all the information in.
