Crazy Carb problems

[Egaeus]

Okay, I have a carburetor that's been sitting for a while on my 99.  Originally, it would idle with choke, but giving it gas or turning off the choke would kill it.  I figured that the jets were clogged from old gas.  I was right about the clogging, but not with what I thought.  The carbs had rust from the fuel tank in them.  The pilot jets were completely clogged, but the mains seemed clear.  They are stock.

So I took a small piece of brass wire and cleaned out the pilot jets, and made sure the main jets were clear, and cleaned out the rust with spray carb cleaner (Valvoline SynPower if it matters).  Everything seemed okay.  Floats looked intact, float valves looked undamaged, jets were now clean, etc.  I put it back together.

I cranked it up, and it started out idling at about 1500.  But instead of staying there like before, as the bike warms up, the revs keep going up.  With the choke on, it tops out at around 5000.  With it off, it's more like 6-7000.  I checked the throttle and cable, and while the cable seems a little tight (turning right revs it up by 500-1000), the throttle goes all the way down to the idle speed adjustment screw when the bars are straight, and it seems to be adjusted pretty far down.  The bike still doesn't like throttle much.  You have to blip it a bit to get the RPMs up until it's hot.  Throttle response seems fairly normal then.  However I'm too afraid to give it much throttle.  It's not far from 7000 to throwing a rod when you're in neutral.

Sooo...any ideas on the cause?  Runaway revs don't seem to be in the Clymer manual's troubleshooting section. 

[skoebl]

My bike has a tendency to do that too. Randomly (usually after it's warmed up a little) the revs will surge up to 4 or 5k. Generally I just turn it off and on real quickly and it seems to temporarily solve the problem. I originally thought it was just the idle screw being maladjusted, but messing with it didn't seem to help any.

I guess next week when I take my bike in to get its much needed tuneup, it'll get fixed 

[scratch]

Make sure the carbs are seated properly, and then make sure the airboots are all the way on, all around the carb mouths.  What condition is the airfilter?  Is it a foam filter, and is it dry?  How much gas was in the tank while it was sitting?  It should be completely full for storage.

The revving up to 4k would be normal with full choke.  Beyond that without choke, methinks the throttle cable is being pulled.

Proper adjustment of the throttle cable should be 1mm of play at the tightest spot (full lock right).

[Mandres]

My guess is vacuum leak.  When you reinstalled the carbs you might have damaged/failed to make a good seal on the rubber boots between either the carbs and the engine or the carbs and the airbox.

[Chris_B]

I think alot of GS's have this problem. Mine does. The only way I've found to fix it is to turn the idle way down, but then the bike wont just idle by itself. Bigger pilot jets might fix it.

[Egaeus]

Unfortunately, I can't shed any light on your suggestions.  I'm going to go ahead and rejet it with 127.5/40 and a K&N in the stock airbox.  I'm waiting for my slow-ass local stealer to get my pilot jets in.  They were supposed to be in Friday.  So much for shopping local to get it sooner....  Right now, the carb is off the bike in anticipation of getting the jets, so I can't try any of your suggestions.

I am almost certain that the boots were sealed.  I spent quite a while making sure they fit right, and was able to tighten them down. 

I am also almost certain that the throttle was loose enough with the bars centered to let the throttle hit the idle adjustment screw.  However, I could be wrong about that, since I only looked when the tank was off.  I do need to adjust the throttle cable, but again, the carb's off right now.

The tank had less than 1 gallon of gasoline in it.  It's really not a  big deal though, because it has to be replaced.  The bike was laid down, and the tank was a casualty.  it doesn't look too bad, but it has a crack that was JB Welded.  That's one reason I got a good deal on it....

The air filter is paper, and it isn't too bad. 

Since it seems I'm not the only one with this issue, I'll be sure and update with any information.  Hopefully I'll be rejetted by Friday.  I still would appreciate any further ideas if you have them.

My next bike will have fuel injection....

[Egaeus]

FYI, it was luser error.  I just assumed (key word there...) that the carburetor idle adjustment screw was set correctly.  Someone was apparently trying to get it to run and adjusted it out too far.  Seeing as I found a second float valve just hanging around in one of the float bowls, nothing should surprise me, and it's something I should have checked....

[carbednotch]

I am having the same issues with my 95 GS as it was also sitting for a fiew years without running. I noticed the idle way up after i sprayed carb cleaner on the jets and in the floats.   
There is a bleeder screw at the bottom of the bowls that i really like.

[Mandres]

Seeing as I found a second float valve just hanging around in one of the float bowls, nothing should surprise me, and it's something I should have checked....

lol seriously?  That kind of stuff really makes you wonder...

-M

[scratch]

Ready service spare?