Rough Idle

[Bob D]

I recently bought a 2001 GL1500 CD with 11,500 miles. It obviously hadn't been ridden much for it's age. It cruises nice but idles a bit rough. It will fluctuate between 900 and 1100 rpms. I've run several cans of carb cleaner through the first 6 fill ups hoping the carbs were just a bit dirty from lack of use. I changed the air cleaner and synced the carbs but the problem persists. I changed the plugs then pulled them after about 500 miles. They all look great, no fouling, etc. There is no stumbling upon acceleration. All the vacuum lines are fine and connected properly. The Fuel petcock holds vacuum as it should. I drained the bowls and no junk came out with the fuel. I've never owned a bike with 6 carbs so maybe this idle fluctuation is normal? My shop manual states the pilot screws are set at the factory and need no adjustment unless they're replaced.

Issue #2- I am getting an oil or fuel deposit where the intake manifold meets the head. It looks like motor oil but I have no idea where its coming from as the bike doesn't have an obvious leak and my garage floor is bone dry. Do I need to replace the O-rings between the intake manifolds and head? I cleaned it up but attached a picture of it starting to build up again. Any comments or suggestions would be appreciated.


 

[Kep]

Yessss...replace those o-rings...I run Techron thru my 97 std with great results.

[Hook#3287]

Congratulations on your purchase.

Looks clean from what can be seen.

Stick with the gas treatments.  Try B-12.  If it doesn't solve it, you'll probably have to pull the carbs and swap out the slow jets.  While there, you should swap out the float valves also.

The oil looks like intake o-rings.  Easy job to do, but if you have to pull the carbs, do it then.  It won't hurt anything to let them be for a while.

[pancho]

Welcome to the world Bob.

Probably what Hook said,, partially clogged slow jets.

[WintrSol]

That drip may be coming from the air cleaner. There is a drain hose that needs to be opened to drain water and oil mist from the crankcase vent from time to time; if it isn't drained, it can back up into the air box and has to go somewhere. It should be a black tube, not far from the RH peg.

[Hook#3287]

WintrSol is talking about the "Dragon Drool" tube.

While I think the oil spot in the pic is the classic leaking intake o-ring, the Dragon Drool needs to be let out.

Under the bike, it should be with the other hose ends, but is the one with a cap.

If it isn't drained regularly, it can back up and create and mess in the top of the motor.

On my Interstate I'm resurrecting, PO's didn't drain it   and it was a oily mess up there and the air box had a coating of oil in the bottom.

I can't remember, but I think some of the hoses weren't attached completely, which would be par for the person that worked on her before I got her.

[Bob D]

Thanks for the input everyone! I will try the conservative approach first and keep running carb cleaner through the tank a little longer. I've used Seafoam and Lucas but haven't tried the Techron yet. I found the "drool Tube", mine is (or at least used to be) clear tubing but there is no plug in the end of it. Does it hurt to just leave the plug out so it can constantly drain? If so, I'll order another one. I will also order a set of O-rings and keep them on standby. Hopefully I won't have to pull the carbs off.

[longrider]

My last two valks have always done the same.  I ride about 20 k a year so it's not varnish in the Jets

[WintrSol]

I found the "drool Tube", mine is (or at least used to be) clear tubing but there is no plug in the end of it. Does it hurt to just leave the plug out so it can constantly drain? If so, I'll order another one.

It is capped to keep unfiltered air from being pulled into the carbs, and, perhaps, to let the oil/water settle out better. I can't say how important it is, but the engineers thought it would be. Perhaps it was a government requirement, as the Suzuki I had used a similar tube, but instead of a plug, it has a clam shell-like end, that you squeeze to let the goo out. I guess, mostly, it keeps your bike from dribbling just anywhere. 

[Hook#3287]

I can't say how important it is, but the engineers thought it would be

I'm with you on that.  Honda engineers have their reasons, their just not good at sharing them.

I believe it's there so the drool can be drained under control, as well as air inlet prevention.

I would replace it.

[sandy]

The intake O rings are a size #123 and you should buy them in viton material. You'll never have to change them again. Yes; replace the plug in the drool tube. The fluctuating idle sounds like intake air leaks. Check all the clamps above and below the carbs. If they suck air, your symptoms appear.

[Willow]

You may have one issue.

The spot looks like intake O-rings going bad.  Bad intake O-rings sometimes result in rough idle.  Check the screws at the top and bottom of the carb tubes to be sure they're tight and you're not pulling in air there.

[Bob D]

OK.....based on everyone's input, I ordered new O-rings and a "drool plug". I also checked all the clamps from the top of the intake manifolds to the air box. I put a few turns on them but none appeared super loose. I also bought some Techron carb cleaner for good measure; what's the harm, right? I'll update after I install the O-rings which should arrive in 7-10 days. I ordered everything from Pro-Caliber as the OEM parts are cheaper than Bike Bandit. If anyone has another OEM parts source that beats Pro-Caliber prices please let me know. Thanks to all!

[pancho]

May want to check Partzilla for prices on your next order Bob,, they sometimes have the best price,, depends on the parts.

Try Barrymans B12 for a fuel system cleaner (about $3 at WalMart) before carb removal,, some including myself swear by it.... but nothing other than replacing the slow jets seems to fix some of them.

[Willow]

OK.....based on everyone's input, I ordered new O-rings and a "drool plug". ...

You ordered a "drool plug"? Silly question.  You weren't running without a plug at the end of the drool tube, were you?  That would not be a good thing.

Usually when one drains the drool one simply pulls the plug out, lets the tube drain, and puts the plug back in.

[WintrSol]

OK.....based on everyone's input, I ordered new O-rings and a "drool plug". ...

You ordered a "drool plug"? Silly question.  You weren't running without a plug at the end of the drool tube, were you?  That would not be a good thing.

Usually when one drains the drool one simply pulls the plug out, lets the tube drain, and puts the plug back in.

Apparently, when the OP bought the bike, it didn't have a plug; also, he said his tube was clear (mine is black), so I suspect a previous owner replaced the tube, and didn't know about the plug.