Idle changes when bike is hot

[ehkmcveh]

Choke the bike to start it when its cold, release the choke and let the bike warm up, idles at around 1100 rpm. Good
But after riding the bike and getting it good and hot, come to a stop...then bike idles around 2500 -2700 rpm.
Is this normal operation?

 

[Tom R]

Nope - your idle circuit is lean. Could be idle fuel screws, vacuum leak, or dirty carbs or any combination of these.

 

[bccap]

Carb boot O rings......

 

[ehkmcveh]

Nope - your idle circuit is lean. Could be idle fuel screws, vacuum leak, or dirty carbs or any combination of these.

I do not suspect leaks since I have been chasing this for a while. Changed the carb boots ($$!!) and the 0-rings.
Changed the airbox boots too and sealed up the airbox as best I could with duct seal.

I did a plug chop on the idle circuit (4th gear at about 30mph for a few miles).
Plug 1 and 4 were black, but the tip was white ish (I usually choke my bike when I warm it up for the 5 min, suspect that where the black is coming from?!?)
Plug 2 and 3 were the same but less black..

All fuel screws are set to about 7/8 out.
Air screws are about 1 1/2 out, I haven't fine tuned them since its hard for me to hear the idle different when turning the screw..

Just wondering WHY it would go up to 2500-2700 when it warms up... why the jump?

 

[Guest]

Choke the bike to start it when its cold, release the choke and let the bike warm up, idles at around 1100 rpm.

Your bike should never idle at 1100rpm when cold just off the choke. My 1100E idles at about 800-850rpm when dead cold, 1100rpm when warmed up. Try turning your idle down to 1100rpm when warm, then see what happens when cold. I do agree with others that your pilot circuits sound lean, but get your warm idle down to 1100rpm first and work from there.

Just wondering WHY it would go up to 2500-2700 when it warms up... why the jump?

Your pilot circuit is lean.


Mark

 

[ehkmcveh]

Your bike should never idle at 1100rpm when cold just off the choke. My 1100E idles at about 800-850rpm when dead cold, 1100rpm when warmed up. Try turning your idle down to 1100rpm when warm, then see what happens when cold. I do agree with others that your pilot circuits sound lean, but get your warm idle down to 1100rpm first and work from there.



yeah I have done that. But when I go to start it cold again, the engine wont stay running without me holding the throttle.
I wonder when its idling at the 2500-2700 when hot, if I pull the choke in (richen it).. would then RPM settle down? can try tomorrow

 

[JJ]

Just wondering WHY it would go up to 2500-2700 when it warms up... why the jump?

It's because something is causing a lean condition. Trust us...

 

[ehkmcveh]

It's because something is causing a lean condition. Trust us...

I trust, I trust!
I did take the bike for another rip today, once the idle went up to the 2500rpm, I pulled on the choke slowly and it started to drop.... guess that's a good sign

Did another plug/chop test this time with brand new plugs.


This is one for the pilot circuit, all 4 look about the same. Did about 3 miles, 4th gear around 30mph.
I thought I would get more colouring than this, but just the tip is white (might have to zoom in, not much colour), LEAN

I cleaned/ rebuit my carbs last year with the VM tutorial on the basscliff's site... so I feel like they are clean.

I clearly cant 100% confirm there is no air leaks, but I spend north of $300 on all new boots/ O-rings

Guess I need to fiddle with the Pilot and air screws a bit more.
Such a bitch getting into pilot screws 2 and 3, all most impossible when the bike is hot

Currently the pilot circuit screw is set for 7/8 out. Air screws are about 1 1/4 - 1 1/2 out.

Setup is stock air box, with k&n air filter, 4-1 pipes.
Did a plug chop on mid and full throttle, also showed lean condition

 

[Redman]

O-rings for the carb boots....?

or

O-Rings for carb rebuild....?


I had similar problem, and was getting worse.
Replaced the carb boots and the o-rings there, and that helped .... some ... for a while ... then came back and... was getting worse.

Was not untill I completely tore down carbs to bits and replaced all the carb o-rings, including the one at the choke plunger, that took care of the problem.

.

 

[ehkmcveh]

O-rings for the carb boots....?

or

O-Rings for carb rebuild....?


I had similar problem, and was getting worse.
Replaced the carb boots and the o-rings there, and that helped .... some ... for a while ... then came back and... was getting worse.

Was not untill I completely tore down carbs to bits and replaced all the carb o-rings, including the one at the choke plunger, that took care of the problem.

.

Both.

You think air was getting in your choke plunger?

So I tried rolling around with the choke part way on... I would be riding then pull in the clutch, rev it up a few times are it would return to 1100rpm ish...good
Went home a put all my pilot fuel circuit to 1 1/8 (air was around 1 1/4).
Rode around (with choke down) and the and the idle would still hang at 2500 rpm

Ok, went and adjust them to 1 1/2... now rode around and the bike runs like junk!

 

[ehkmcveh]

Hurts to trying to adjust the pilot fuel on the VM when the bike is hot, had to rap my hand to get in there but my knuckles are felling it

 

[BigD_83]

You say that you are lean through the entire throttle range...I wouldn't have thought that a 4 into 1 would in and if itself cause that, but that along with a too-dry K&N filter...maybe? What are you running for jets?

 

[ehkmcveh]

ALright figured why it was running like junk, carb 3 pilot was at zero (tried to adjust it hot)
I guess I will only adjust it when it was cool

Tried the pilots at 2 (air at 1 1/4) for fun.... Idle seems to fluctuate even more now, was having a hard time getting it to settle
But went for a ride, the low power pulled Ok, but when it got good and hot the idle hung at 2500rpm

Sprayed carb cleaner to look for vacuum leaks. kinda hard to determine when you have a wandering idle anyway. Didn't see much changed

Might just return it back to 7/8 and say the hell with it, it rides fine

Just one thing I don't understand is that it smell really gassy, like its on my cloths (in a lean condition?)
Anybody experience this?

 

[ehkmcveh]

You say that you are lean through the entire throttle range...I wouldn't have thought that a 4 into 1 would in and if itself cause that, but that along with a too-dry K&N filter...maybe? What are you running for jets?

102.5 Main
15 Pilot

What do you mean too dry, should I be oiling it ever season?

 

[Guest]

Are the valves adjusted? Compression checked?

 

[BigD_83]

102.5 Main
15 Pilot

What do you mean too dry, should I be oiling it ever season?

I don't think you'd have to oil it every season, but certainly every time you clean the filter. Given your location, I'd expect a lot of hot, dry days during riding season, so perhaps your filter has dried out a tad. Wouldn't hurt to have a look.

As for the jets, that is the stock pilot air jet, and 1/2 size up on the main. That pretty much meshes with what I've been told about headers.

 

[ehkmcveh]

Are the valves adjusted? Compression checked?

Well I rebuilt the top end about 600 miles ago.
I checked all valves there and changed about 4 shims... all within the 0.03mm to 0.08mm
Compression I have not done yet, want to give it time to marry to the cylinder...I'm sure its good cause it hauls ass full throttle!

 

[ehkmcveh]

anyways, been talking with some other guy in my hometown
He suspect dirty carbs, so got them ripped apart and going for a 24 hr bath... Changed all 0-rings last year but did find on that was pinched on carb 3 pilot air screw... not sure if that would be the cause of the hanging idle!

 

[Guest]

Well I rebuilt the top end about 600 miles ago.
I checked all valves there and changed about 4 shims... all within the 0.03mm to 0.08mm
Compression I have not done yet, want to give it time to marry to the cylinder...I'm sure its good cause it hauls ass full throttle!

I'll take that as a no. Had a similar hanging idle situation last week; turned out to be an unnoticed slightly bent valve. Pulled hard wide open. A leak down tester picked up on it better than a dynamic compression test.

If you don't have full compression by 600 miles, more miles probably won't fix it.

 

[ehkmcveh]

I'll take that as a no. Had a similar hanging idle situation last week; turned out to be an unnoticed slightly bent valve. Pulled hard wide open. A leak down tester picked up on it better than a dynamic compression test.

If you don't have full compression by 600 miles, more miles probably won't fix it.

Well I don't have access to a leak down compression tester..... probably should find one since I'm this deep already.
Bent valve hey! what do you think/suspect that was from.

I could do a compression test tomorrow and re-check the valves while I wait for my jets to finish the carb dip bath.