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Discussion Starter · #1 ·
For the year I've had my KZ750H3. the engine has seemed to be running richer and richer. Now, it still runs strong and starts fine, but it smokes out both tail pipes. This is rich smoke-not oil smoke. It's not strong and can't be seen well when going down the road, but when tuning in my garage it gets pretty bad in there.

What's the first thing to check (the choke works fine by the way)? Thanks!
 

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Discussion Starter · #4 ·
Passages are not restricted, but the filter could be dirty. It looks pretty clean but I'll change it out anyway.

However, above idle the exhaust gets cleaner. It has CV34 carbs, which have a idle speed screw (maybe another name for this) at the top. The screw holes are supposed to be capped, but the caps are gone showing the screw heads, and I am wondering if they might have viabrated out of adjustment? Is there a specific adjustment for them, like say 2 turns out from seated?
 

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I seem to recall Wiredgeorge telling me something about some sort of seals in the enrichener circuit (choke) that would make the bike run rich at idle if they leak. Do a search for wiredgeorge motorcycle carbs on Google and contact him at his site, he can probably help you.
 

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Same carbs that I have. I don't recall any "seal" in the enrichner mechanism but there is a rubber boot of sort that covers each one of the plungers. I would think if anything, a leak around there would only allow more air in to make it leaner. There is a seal (o-ring) on the small plugs that cover the pilot jets and if this is worn or bad it would allow more fuel to get to the pilot jet and might cause it to run richer.

The screws you mentioned are not idle screws, they are mixture screws and are not set the same on all bikes or carbs.
 

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Discussion Starter · #7 ·
Stargate, you said.....

"There is a seal (o-ring) on the small plugs that cover the pilot jets and if this is worn or bad it would allow more fuel to get to the pilot jet and might cause it to run richer."

Hummm...I think know what you are talking about, and the little caps that cover the pilot screws are gone. You can look down in there and see the screw (jet) heads. But (and I may be thinking in reverse here) if air can get in past the screws, wouldn't that cause it to run leaner? Do you know how far out from seated those screws should be?
 

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The plugs and o-rings I'm referring to are viewed from the bottom with the float bowl removed. The screws you are talking about are viewed from the top. There is no "set" or "standard" setting for the mixture screws since they need to be set/adjusted for your particular running environment (altitude) and bike setup (4-1, pods, stock exhaust, etc). Their setting will also change if you change the jets. A good starting point when starting from scratch with everything stock would be to set them at 1.5 turns out from lightly seated, then start the bike and adjust them as necessary for best performance.

P.S. Having the plugs removed to expose the mixture screws is not a problem (I drilled and removed mine long ago). If the o-ring around the mixture screw is leaking it will cause it to run leaner and possibly an unstable idle.
 
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