Topic: CB500 — hanging idle? [solved]

[BobbyR]

Excellant! Glad it worked out and sharing.
 

[harisuluv]

Yeah hence the problem a lot of times when these carb threads (not specifically yours)

Just start off "cleaned the carbs, so that's NOT the problem!"  Then it turns out something simple. 

Thanks for following up with the fix, that will help someone in the future when they search for it.  Good job.

[Scott S]

• Replaced float hardware w/ sockets (can change jets w/o removing!)

What do you mean by this?

[harisuluv]

• Replaced float hardware w/ sockets (can change jets w/o removing!)

What do you mean by this?

I think he means he replaced the float bowl screws with allen heads.

[Scott S]

That's what I thought at first, but then he add the part about changing jets without removing.....confused me.

[sammermpc]

I think he means he replaced the float bowl screws with allen heads.

Exactly. With stubby mini screwdriver set (have a nice one specifically for motorcycles from Chapman mfg) , I can get into the float bowls without removing the carbs from the bike pretty easily. Useful for those of us who need to constantly try different jets...

ANYHOW — yes. Especially for those of us who haven't cleaned carbs before, it's easy to think they're "clean" without realizing that there are parts that dirty. My face is a bit red, but glad to get it done!

[stu2211]

Thought I'd update here, just for the other folks who are inevitably going to run into this common set of problems — after everything was said and done, as many others have, replacing the pilot jets with Keihin #40s made the difference. Swapped them in, and boom — hanging idle was gone.

Embarrassingly, I don't think I actually cleaned my OEM #40 pilots well, despite trying many times. I did not realize there was a hole at the end of jet, which was always clogged, and causing it to run lean on the pilot circuit. When I finally got a new set, I realized my mistake.

Of course, in this process, I:

• Replaced intake, output boots & manifold o-rings
• Replaced points & points plate
• Trimmed advancer springs 1/2 turn
• Set valves & timing
• Vac sync'd
• Replaced float hardware w/ sockets (can change jets w/o removing!)

And yeah, I think I probably could've skipped all of that by just replacing the pilots! All the same, so glad to get it running. Took a beautiful ride last weekend. 

Here she is in full-regalia (looking for a windscreen):

I created an account specifically to reply to this thread - I ran into this exact problem and started down the path of messing with idle air screws, then thought my next step would be floats and carb syncing before finding this.

All I can say is thanks - the new slow jets fixed my warmed up hanging rpms 100%! It's amazing that I managed to stumble on a solution where somebody else had the same problem years and years ago and went through the work of figuring it out. I don't doubt that I'd otherwise be spending weeks on this, tearing out my hair.

[jonda500]

hmmm, great that you's have fixed it, but why did you not just simply clean the hole running through the original pilot jets that was clogged? Couldn't find anything suitable to poke through it?
John

[stu2211]

I already tried soaking it in carb cleaner which is why I didn't immediately think that would be it.

I'm super new to dealing with carbs - I wanted to cut down on the variables that could be causing the problem. Buying new jets was worth it to me vs trying to clean them again (and not knowing if I did a good enough job), spinning my wheels, and wondering what else it could be.

[dave500]

brass parts can be soaked in vinegar for ages no damage,they come out rose gold,just clean em off with some fine steel wool and abrasive houshold paste,also a guitar E string makes a great small hole poker/probe for next time.