Newbie needs help with hanging idle?

[stodman]

81 GS450TX, 7,600 miles
Thanks to this amazing website and guys like Steve, I, knowing nothing about bikes at all, have now:

Fully cleaned and rebuilt carbs per tutorial, new o-rings, float height adj.

Bench synced carbs

Checked valve clearances, all 4 are between .004 and .005 mm

new boots on air box

new o-rings on intake boots

New air filter, oiled and nested correctly

Weather stripped air scoop on top of air box

Inspected and cleaned petcock


After all this, the bike started right up, briefly idled around 1200, then revved to 3000-3500 and stayed there. Messing with the throttle adjust screw and the mixture screws (currently at 1 1/4 turns out) did not make much difference.

Other than that the bike sounded silky smooth.

Where do I go from here ? Please help, I'm thinking maybe the intake boots need to be replaced, but they actually look and feel o.k.-ish


Stodman

Hoping to take my first ride before the snow flies

[Nessism]

The GS bikes will scream at a high idle with the choke pulled. Could this be the reason? If not, what happens when you turn the idle speed screw and drop the speed?

BTW, it's a pleasure to offer help to someone that has done the basic maintenance like you have.

[Guest]

Welcome along, and yeah it's great to see you've taken the time to go through all the basics first

Have you checked to make sure your throttle cable is lubed and not binding anywhere?

[stodman]

Ok, this is how little I know.

Is the choke on or off with the lever in the up position.

Stodman

[stodman]

Latest update,

Just started up cold, very easily, with choke lever down.

Idled at 1200 for a minute or two, and returned to normal idle when throttled.

after a couple minutes, idle crept up to about 1500 and then started to hang up at 3000 rpm. I played with the choke lever and was able to bring the idle back down around 1200 by lifting the lever very slightly, but that doesn't seem like the answer, just a bandaid.

Also, as far as I can tell the throttle cable is not hanging up at all, the throttle do-hickey on the carbs fully returns to the adjustment screw each time.

Is this possibly an air leak around the intake boots? Would that explain the racing rpm once the engine is warmed up a bit? Any input is greatly appreciated.
Stodman

[dueller]

With the choke on

the idle will rise. It is richening the mixture to help with the engine being cold. So giving less choke should drop your idle.

[Guest]

The choke should be on when the lever is pushed down. It works by a lever action which means pushing the lever down raises the choke actuators on the carbs and activating the choke.

It's not something simple like your idle screw is screwed too far in and setting the idle too high?

Try winding the idle screw out til it idles at the correct speed when it's warm, then give it a few rev's and see if it still hangs high...

[JCSkokos]

It's not something simple like your idle screw is screwed too far in and setting the idle too high?

Try winding the idle screw out til it idles at the correct speed when it's warm, then give it a few rev's and see if it still hangs high...

This is what I was thinking. You said it will start fine cold with the 'choke' all the way down? Try warming it up till it starts idling high then turning the big screw on the bottom of the carbs to drop it down to normal. Then on the next (cold) start up, pull the choke up and see if it starts good cold.

[stodman]

Ok, you guys rock, and I have rocks in my head,

I thought choke off was lever down, so that was the cause of all me problems,

Once you edumocated me, I levered up (choke off) adjusted the idle screw and tweaked the mixture screws 1/4 turn out, AND NOW SHE PURRS LIKE A KITTEN. BIG SMILE, THANK YOU!

My buddy's coming over tomorrow to take her for a test ride, since I still don't know how to ride. That may change very soon.

Stodman

[Guest]

Good stuff!

Better to find your choke on than to find something drastic wrong with your carbs