High Idle 1981 GS 1000

[Guest]

Well guys I have been working on this bike for awhile now, cleaned carb and rebuilt carbs. Replaced intake boots on both sides of carbs. The bike will start and rev up fine, after bike warms up the idle wont drop down. The weird thing is if I had an air leak and I pulled the choke it should bring the idle back down. It doesn't it keeps the idle high and cant get it adjusted or tuned. Anyone have any thoughts, it would greatly be appreciated.

[Steve]

Air leak, likely in the intake boots.

If the boots are in decent shape, you might only need the o-rings, but you will likely need o-rings, regardless.

Get your o-rings at Cycleorings.com.

The 'proprietor' there is a member here and has MANY repeat customers for his fine products.

.

[Rob Stretch]

All the boots are new as well as O-Rings

[Redman]

.... The weird thing is if I had an air leak and I pulled the choke it should bring the idle back down. It doesn't .....

Nope. If air leak is the O-rings in the intake boots (at the head) then that air that is leaking is not going thru the carbs.

Also keep inmind the the GS choke is not really a choke (it is an enricher).

If after it warms up, and you turn down the idle some, then next time the engine is cold you have to turn the idle back up and back-n-forth, that is one sign that you have the air leak.
If after it warms up, and you rev the engine and the idle speed doesn't come down, it "hangs high" that is another sign.
If after it warms up the idle goes high and keeps climbing as it warms up more, that is another sign.

Biggest suspect is usally the O-rings in the boots. IF they are 5-10-15 years old and/or engine runs hot a lot, they are probably not really rubber-silicon anymore.
Other suspect can be the boots them selfves, look for cracks, or if so hard and deformed that cant really get them to fit to the carbs well.

Are other suspects also.

I fought it and fought it, until I did complete carb teardown and cleaning and replaced the O-rings around the choke mechanisms (er, um, enricher mechanisms).

Do online search for Cycle O-Rings (a fine GSR member here).

>> opps, now see your post about new boots and O-rings.

[Steve]

What are your settings on the mixture (pilot) screws?

If they are too far in, you will be running lean, possibly showing those symptoms.

Start with them three full turns out from lightly seated,

If that helps, after the bike warms up, you should be able to turn them in slowly, listening for best eingine idle speed.
The screws might end up in the 2 to 2 1/2 turn range, but starting at 3 will make things easier.

.

[gustovh]

Well guys I have been working on this bike for awhile now, cleaned carb and rebuilt carbs. Replaced intake boots on both sides of carbs. The bike will start and rev up fine, after bike warms up the idle wont drop down. The weird thing is if I had an air leak and I pulled the choke it should bring the idle back down. It doesn't it keeps the idle high and cant get it adjusted or tuned. Anyone have any thoughts, it would greatly be appreciated.

I assume that your cables are with the correct slack and that you have attempted to turn down the idle adjustment screw...sometimes it takes quite a few turns on the idle adjust after a carb clean to get it to idle down. There is a possibility that one of the O rings was pinched on install.

The carbs are so easy to remove from your bike, I would pull them and check em over again and blow em out again just for measure and re install. Just might do it for ya.

V

[Rob Stretch]

we have completely eliminated all the boots by buying brand new boots with new O-rings and then silicone-d the O-rings, and it doesn't matter where the idle mixture screws are at, the bike does have a Kirker pipe, valve lash is good, where it is leaking is on the throttle shaft that holds all the butter fly valves on it, or atleast close to that area, we are also thinking it could be leaking into the enrichener assemblies, any idea on how to fix that issue with out ordering parts??? on a parts-fiche we see seals on that shaft that are pressed into the carb bodies. was wondering if there is a "quick fix" for that issue, or were the GS product line known for that??? it is a old bike that has sat for about 5 years, all four plugs are burning very good(light caramel color) which is weird for that high idle scenario,

[tdeglass]

I am having the same issue, but my problem seems to only be with carbs 3,4. I have soaked, scrubbed and poked out all the jets, ports and passages during a rebuild. I used all new rubber parts during the rebuild. I have replaced the boots and O-rings for the intake manifold. I have sealed the air box boots where they enter the air box. I have sealed the air box with weather stripping, and I have replaced the snorkel (it was missing). I have confirmed that the boot clamps on both sides are tight and not leaking. I have verified throttle cable slack, confirmed adequate fuel supply, checked choke cable and actuator function. The bike runs great at 1/3 to full throttle. The bike idles OK when cold. Total dog off idle when cold, in fact, it will stall if I try to take off before it is really warm. Once engine warms up the idle stays high after blipping the throttle. Troubleshooting: When I spray starter fluid on or around carbs 1,2 the engine speed remains constant. When I do the same around carbs 3,4 the engine rpms pick up. Did I mention that the manifold boots and O-rings are new.

I obviously have an air leak around 3,4 carbs. I think the leak may be on the carbs, perhaps somewhere around the shaft seal area. I haven't heard the shaft seals mentioned on any of the other threads when addressing this lean/air leak issue. Maybe I missed something. Are the shaft seals a possible culprit?