Topic: Continuing saga of performance problems...

[Super Sport 550]

You may recall that I was having performance problems a few days ago. The bike had no power and wouldn't rev above 5000-6000 rpm. The timing has been set and the spark plugs are new.

So I got a new battery and hooked everthing up and took the bike up and down the driveway...

It still does it. However, I went a bit further into the diagnosis. The bike doesn't run better with the choke partially applied. It actually runs worse. Also I noticed that when I rev the engine hard I get a slight black haze out of the exhaust. Leads me to believe it is running rich, but why? The air box is once again disconnected, and it still does it.

 

Then I noticed a new phenomenon. When the engine gets good and hot, it won't idle down. It won't go below 3000 rpm. Not that it will stall If it does, it simply won't do it. I have tried adjusting the idle stop screw and it doesn't seem to have any effect. Funny because it never did that before...

[byidesign]

Sounds like it's getting air from somewhere,{leaking booties?}or
    fast idle assy. is stuck on?. { carbs badly out of sync?}
   if you have the air cleaner off, can you see
     if all the throttle plates close?
           Post what you find....
               Hope it helps
                        Bruce

[Lumbee]

...just so we are clear, the air box should be on from here on out.  Not sure on the 550's, but the carbs on the 750's, the needles can be adjusted.  Maybe your needles are adjusted to high...hence the high idle...

[crazypj]

Its running lean at idle and real rich higher up.
remove carbs and check the none of the jets have fallen out  or are in upside down (or maybe just 1 main) dont laugh, I've seen it happen. the spring plates holding jets in position are OK?
Check the pilots with a magnifier to make sure they are completely clean, you can ge oxidation inside them so they look ok but are restricted
PJ

[Super Sport 550]

Well, I can't do too much now. The bike quit and won't start back up. Looks like time for some carb work!

Sounds like it's getting air from somewhere,{leaking booties?}or
    fast idle assy. is stuck on?. { carbs badly out of sync?}
   if you have the air cleaner off, can you see
     if all the throttle plates close?
           Post what you find....
               Hope it helps
                        Bruce

The carb boots are ok. I didn't know that it had a fast idle... Carbs could be poorly synchronized, can't tell for sure yet. The slides are all going down. I am leaning towards the airbox being disconnected again causing the fast idle, but I don't know what is causing the rich running up top.

...just so we are clear, the air box should be on from here on out.

It was, but when I saw the black smoke I disconnected it to see if it changed anything.

Its running lean at idle and real rich higher up.
remove carbs and check the none of the jets have fallen out  or are in upside down (or maybe just 1 main) dont laugh, I've seen it happen. the spring plates holding jets in position are OK?
Check the pilots with a magnifier to make sure they are completely clean, you can ge oxidation inside them so they look ok but are restricted

I I will be taking the carbs off, so I will check those things.

Thanks for the help! I think I'll go through the carbs and see what I find.

[HondaMan]

My 1st thought: air filter. Use paper filter or K & N on the 500 family, because the foam ones are small and tend to cause hi-RPM richness.
Next thought: clogged idle (gas) jets or low float level in 1 or 2 carbs.
A longer shot: intake valve(s) too tight (lash adjustment) and timing too short, like timing is late or points gap too small.
Last check: make sure the carb hoses to the head don't have any leaks or cracks.