Idle speed setting

[Anonymous]

So this morning it was pretty darn cold. I managed to get the bike to start, but even after warming up a bit, it was still running rough. I reached under the carbs and sped up the idle throttle setting a bit, and things got better. Made my way into work for the daily grind....

When it is time to go home, I return to the bike, and I can't get it started. I figure between the cold and the half charged battery (from the difficult starts & short drive times) I just need to charge up the battery. Walk home, charge it up for a few hours, return to the bike w/ the truck & ramp just in case. Throw in the battery, and she cranks good & strong. Won't start.... Keep trying for a while & then I realize that I had messed with the idle throttle setting. With my bike, when it is cold, full choke, and don't even think about touching the throttle, or it'll never start. Drat! Well, by now, I've used up most of the battery, and no hope in sight of getting it started. Furthermore I've lost track of where the idle screw was supposed to be.

So, I try to load up the bike, takes three or four tries, fell off the ramp once & nearly lost it. Not a pretty sight... Get it home, go to unload, and halfway off, the ramp gives. Turns out, the metal tines at the head of my homemade ramp had fatigued & lost all their strength. Try to get the ramp onto the bumper instead of the tailgate to get it down, lookin good, until the ramp slips & I dump the bike. I used to have only one rear turn signal....

Finally get the damn bike parked & that brings me to you...

Dead battery, cold bike, no turn signals, and no idea whatsoever where the idle throttle screw should be set.

Any suggestions?

'85 GS550 L (of course, w/ the 2 weird double-barrel carbs.)

Rob

 

[Anonymous]

Just turn your idle adjuster back one or two turns, or enough so the throttle cable is no longer doing anything and the slides are sitting as low as they can. You will feel when the cable has slack in it by the feel of the twist grip.

Kim

 

[Mr. Jiggles]

If it's simply a matter of idle setting then I'd expect that it would be cured by giving it a bit of throttle as you're cranking it. Are you sure that something wasn't disconnected while reaching to get to the idle knob? Was your rough idling serious enough to make you think that it is linked to it not starting (i.e. has gotten worse to the point that it won't start)?

 

[focus frenzy]

people people people, his problem is he adjusted the idle speed up, that combined with the 550s normal lean condition is preventing it from starting.
he wants to know what the standard setting is for the idle speed screw.

when the idle speed is increased the throttle plate openings are increased allowing in more air, the problem is that when cold this cuts down on the fuel drawn through the choke circuit and you get a bike that does not start cold.

unfortunately there is not a standard setting other than by warm engine speed. (12-1500rpm for a 550)

the choke used on these CV carbs is not really a choke but a enricher.
when the choke is engaged it opens a bypass port allowing air to bypass the throttle butterfly's and it gets extra fuel from the choke jet, sort of like a mini carb that is inside the main carb, except it is jetted real rich.
if the idle speed is set to high or the throttle is opened the vacuum through the choke circuit drops and you don't get enough extra fuel to start a cold engine.
personally I prefer a old fashion choke butterfly upstream of the main jet with a high idle cam, they work better under varying conditions and work when it is very cold, enricher's have a limited temperature range they work at.

 

[Anonymous]

Thanks everyone

Thanks everyone

Thanks for the clarification there, you did a much better job of clearing up my problem.

It was relatively warm today, which helped me get it going. I backed the screw way out and managed to get it to start. It would run for a few seconds & die. I then started bringing it back in. Finally I got into a reasonable range & got it decently adjusted. The tach is broken, so I just had to do it by ear. I think it is pretty good...

Well, I guess it is time to order some turn signals... & bars... & mirrors...

Thanks again,

Rob