Strange idle problem

[bukwheat]

I have a wierd problem with my 11 300. When I go out for a ride, I will start it up and let it warm up a couple of minutes. Everything seems fine. I have a loop that I ride that is about 7 miles in length. About half way thru, if I stop for second I notice the idle is higher than normal. If normal idle rpm is around 600rpm, it will be idling at 900 to 1000 rpm. I can adjust the idle down and it seems almost okay. While riding, everything seems normal, it runs good and has good normal power. It almost acts like an air leak somewhere. I have removed and totally gone thru the carb. I have removed the airboot to look for cracks. I have checked the reeds and cage. I am running 50% 93 octane pump gas and 50% 100 octane race gas mixed at 50:1 Amsoil.

Anybody got any ideas....I've been riding 2 strokes for over 40 years and I've never had a problem that has eluded me like this.

[pscook]

Originally Posted by bukwheat

I have a wierd problem with my 11 300. When I go out for a ride, I will start it up and let it warm up a couple of minutes. Everything seems fine. I have a loop that I ride that is about 7 miles in length. About half way thru, if I stop for second I notice the idle is higher than normal. If normal idle rpm is around 600rpm, it will be idling at 900 to 1000 rpm. I can adjust the idle down and it seems almost okay. While riding, everything seems normal, it runs good and has good normal power. It almost acts like an air leak somewhere. I have removed and totally gone thru the carb. I have removed the airboot to look for cracks. I have checked the reeds and cage. I am running 50% 93 octane pump gas and 50% 100 octane race gas mixed at 50:1 Amsoil.

Anybody got any ideas....I've been riding 2 strokes for over 40 years and I've never had a problem that has eluded me like this.

There is another member who made a new mixture screw (or idle screw?) to cure an intermittent idle issue. I'll look for the thread, but one of the adjustment screws leaked enough to cause intermittent idle issues similar to yours.

[Simmo737]

Have you recently adjusted the throttle free play using a stock throttle cable?

[n_green]

Have you checked the stator side crank seal behind the flywheel? If that's leaking it will suck air.

Looks like this when it's leaking:





Thats a KTM seal/stator but same same.

[Jakobi]

What does going in the air screw a quarter turn do?

Has the temp changed recently? Got colder? .. and all above

[bukwheat]

pscook

There is another member who made a new mixture screw (or idle screw?) to cure an intermittent idle issue. I'll look for the thread, but one of the adjustment screws leaked enough to cause intermittent idle issues similar to yours.

Did he actually "make" an air screw? or buy one?

n_green

Have you checked the stator side crank seal behind the flywheel? If that's leaking it will suck air.

Nope, haven't done that yet. If it is a bad seal on that side, will I need to split the cases?

Simmo737

Have you recently adjusted the throttle free play using a stock throttle cable?

No, this started generally "all of a sudden"....had not done any tweaking/adjustments or maintenance.


Jakobi

What does going in the air screw a quarter turn do?

Has the temp changed recently? Got colder? .. and all above

I tried adjusting it a couple of rides ago and if I remember correctly, it doesn't have much affect. Right now it seem to be adjusted all the way in...which I know can't be correct...The temp here doesn't deviate too much this time of year. The last couple of rides have been probably 55 degrees + or - 5 degrees. I have a video of my last ride where I adjust it and you can hear how it sounds. I will try to get that edited down to the area of interest and post it but it will take me a couple of days....stay tuned and thanks for all of the suggestions so far, gents!

[Neil E.]

Originally Posted by pscook

There is another member who made a new mixture screw (or idle screw?) to cure an intermittent idle issue. I'll look for the thread, but one of the adjustment screws leaked enough to cause intermittent idle issues similar to yours.

More info in this post about the slide stop screw I made. The stock screw became sloppy after I removed it and disturbed the factory thread sealer.

http://www.gasgasrider.org/forum/sho...5&postcount=15

[Jakobi]

I noticed that my idle speed/slide stop screw has a bit of slop in it and will back itself out a little bit with vibes or when the slide slaps on it a bit. It can make it want to stall or die out a bit on occassion but I haven't had it cause a high idle.

[n_green]

The stator side crank seal doesn't require cases to be split to replace. Just a lot of time, patience and swearing to get the old one out and new one in.

As seen in my pics it's obvious if it is leaking and is easy to check so long as you have a flywheel puller.

[n_green]

Originally Posted by Jakobi

I noticed that my idle speed/slide stop screw has a bit of slop in it and will back itself out a little bit with vibes or when the slide slaps on it a bit. It can make it want to stall or die out a bit on occassion but I haven't had it cause a high idle.

I noticed the same thing. The spring isn't quite long enough to place sufficient pressure on the screw when backed out to set the slide height correctly. But it hasn't caused me any problems at all.