Engine starts to rev up with no hand on the throttle

[Steel cowboy]

On my trip to Daytona this weekend ( that's why I wasn't at the pizza party) I got into some traffic when I got to the light my throttle was at 1100 rpm and it started climbing up to 2000 by itself. I smacked the throttle but I could not get it down. I had to shut the engine off for about a minute or so, then it started at 1100 again. I have recently replaces the intake manifold o rings and the bad vacuume lines too, that took away my hesitation but this has happened once before too. I'll be checking on the carb sync on Thursday with my buddy Steve. Any thoughts on this will be greatly appreciated.
 2001 I/S 37,440 miles.  Thank you.

[Michvalk]

I assume that it was OK after the o-ring work, then went bad afterward. Check to make sure all the hoses are still in place. Check all the clamps on the carbs. (there are 18) Just go over everything you touched while doing the work.
Could be something else, but usually that is a vacuum problem

[Chrisj CMA]

Turn the idle down to 900 or so

[grepper]

I agree with Michvalk, sounds like a vacuum leak or intake manifold leak.

One trick to find such leaks it to get a can of carb cleaner or starter fluid with a straw on the end so you can focus the spray.  With the bike idling, spray a place where you could have a leak, wait a few seconds and if the idle climbs/changes you found your leak.
Do this before trying to sync carbs as to not try to sync to compensate for an over lean condition on one or more carbs.

[Steel cowboy]

I used the starting fluid to find the vacuum leaks the first time. 1 vacuum line and 2 vacuum plugs were bad. All the manifold o rings were bad too. I'll try to find some more leaks before the sync when I get home. It sounds weird to me that a vacuum leak would cause the engine to rev up that high, but I will try all your suggestions at this point. Thanks guys !!!!

[Bagger John - #3785]

...It sounds weird to me that a vacuum leak would cause the engine to rev up that high...

A vacuum leak on one or more cylinders will cause a lean-out condition. Better burn (more complete combustion) of the fuel-air mix at low speed with the extra oxygen. Put a load on the engine, however, and it falls flat on its face until the slides open further, admit much more air and the mid-range jetting takes over.

[Ricky-D]

That happened to me one time and I was at a loss trying to determine what happened and what caused it.

My engine revved a bit higher, closer to 2,000rpms. I continued to ride however and a short time later

everything returned to normal and it has not happened again. I surmise that a slide temporarily must have

gotten stuck, for whatever reason, and fixed itself. If it were to occur again I would definitely feel the need

to investigate what is actually going on. But since then, nothing has happened, and I'll simply chalk it up

to an anomaly and not worry about it.

***

[Steel cowboy]

 OK so I check for vacuum leaks with starting fluid and  there are none, the engine rev'd back up again today to about 2500 RPM without me touching the throttle the idle is set at 950.  I turned off the engine and waited five minutes when I restarted the engine it was running again at 950.  Could the engine be overheating, I checked the fan by grounding the plug and it did turn on.  Could the petcock on the vacuum side be sucking fuel into the number six carburetor manifold. I am STUMPED !!  By the way this always seems to happen after I've been going at a high speed and slow down and drive at a slower speed.
 Would adjustment of the pilot screws have anything to do with that, if one of the carbs or more than one was out or should they be set at a certain opening and left alone. I am going to try the carb sync later on today.

[big poppa pump]

Sounds more like the one or more of the carb butterfiles are stuck and not closing all the way in. A good carb servicing will help resolve this problem.

[Steel cowboy]

I am starting to lean that way too.

[Kirb]

Toss a can of seafoam in the next tank to see if it stops. If it does I am betting a butterfly is sticking

[gordonv]

Toss a can of seafoam in the next tank to see if it stops. If it does I am betting a butterfly is sticking

Since this isn't jets, is Seafoam something good to use, or just stay with the better cleaners like B-12 and Techron?

Is it cleaning the same thing? Fuel fowling.

[Steel cowboy]

Well we (steve & I) did the the carb sync this afternoon and I did not believe it would do much to fix my problem. The good news is that it did, I had to keep turning the idle down to get it at 950 rpm's. Two of the carbs were substantially off (2 & 6) the others were off just a bit. But I had to turn the idle adjustment down 2 full turns !!!
I still have a lot to learn about this bike, the P/O spent a lot of money and had it serviced by many different shops. I fixed the manifold leaks that someone used silicon on the bad o rings. I fixed the cracked vacuume lines that caused issues with hesitation. The rubber card boots that were never tightened down too.
Slowly but surely I'll get her dialed in like my Sabre. I do want to thank Steve and everybody that helped with their suggestions. Tomorrow Steve and I are going to try and get lost somewhere in Sumter county, it's what we call going for a ride.

[Steel cowboy]

As I recall Seafoam is an active cleaner it cleans as it flows thru your carb's and jets.
Lucas is a passive cleaner it cleans as it sits in your tank and cabs.

[Paladin528]

My Bike is exhibiting the same symptoms only not as bad.
One thing I did notice is that a slight turn of the idle knob when it is running high will settle it down.  Along with the high idle it also takes a long time to settle down after releasing the throttle.
It only exhibits this behaviour when hot.
I am assuming I need a sync to settle it down permanently.

[Kirb]

There may be better cleaners out there. I have had good luck with seafoam. Use it with oil changes to clean as well. I wouldn't use a cleaner as a solution though simply as a way to reach a conclusion. If the seafoam or other cleaner works it is carbs and they need some love