Strange idle problem

[bukwheat]

Strange idle problem with video posted

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]

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.]

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/showpost.php?p=74225&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]

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.

 

[bukwheat]

Here is the link to the video with the idle problem at the beginning.

http://www.youtube.com/watch?v=mwW7-2FyzPU

 

[hannesd]

did you get your squish set correctly?
exessive squich (as on most standart bikes) can lead to irregular idle.
makes them very sensitive to changes in temp/altitude.
next thing that comes to mind is also a blown crank seal.
just a thought.
does it sound like it's running somewhat rich off idle? (edit : after watching the vid longer, definately running rich off idle if you ask me, doesn't run crisp)

hope you get it fixed soon.

ciao, Hannes.

 

[bukwheat]

The squish should be good, never have had the head off. Its totally stock. I think what you're hearing is me lugging it in higher gears. I usually run 3rd or 4th gear in pretty tight woods. It could probably run a bit cleaner.

 

[hannesd]

The squish should be good, never have had the head off. Its totally stock. I think what you're hearing is me lugging it in higher gears. I usually run 3rd or 4th gear in pretty tight woods. It could probably run a bit cleaner.

if you never had the head off, then most will confirm that you get a much more consistent idle when you get squish corrected.
i'm doing the same to my 200 now.
alot of the 300's have a standart squish of aprox 2-2.3mm, wich is exessive.

you could get that sorted, you'll benefit from the extra torque and fuel economy aswell

 

[Jakobi]

Its true that reducing the squish helps stabilize the idle alot, but its not the issue here.

2 things I'm hearing/seeing.

1) It doesn't sound lean on the pilot or needle.
2) It definitely sounds lean at idle.

So.. If it was me I'd personally be looking for an air leak somewhere. It only takes a little crack in the intake manifold to allow it to race. You may have to take the manifold off the bike and hold it up to a light while manipulating it to be sure. Other than that stator side crank seal is next most likely candidate.

Or has someone just cranked your idle speed right up on the sly when you werent looking?

 

[Jakobi]

Also, does it race again now if you go and start it?

Do you run an inline fuel filter? Any chance it was just something jammed in the pilot at that moment?

 

[GMP]

Lean pilot ckt. symptoms, if it not real lean, sometimes don't rear their ugly head until you come down from RPM, and/or off high load, like at the end of a straight. I noticed this setting up my '12. I'd just make sure all is well with air leaks and fuel and try one up on the pilot.

 

[bukwheat]

Good news!!!

Just got around to working on the bike as I have been down in the back for a couple of days...

I owe Jakobi and GMP a beer! Lean pilot was the correct diagnosis. I had removed the pilot early on, I could see thru it so I figured it was clear. I went down and talked to Bill who is my GG dealer at Dirt Bike Supply. He suggested the pilot jet also. He gave me a hand full to try, as I wasn't really sure what was in it. He gave me a 38, 40, 42, 45, 48 and a 52. I pulled out my old pilot jet which was a 42. Again, I looked thru it, could see daylight....I took an old high e guitar string that I use to clean jets with and ran it thru my old one, it wouldn't go all the way, alot of resistence. I took the brand new 42 and it would go thru with no problem....so....my old 42 had clogged enough to make it lean.

I put the 45 in and just got thru checking it out. After a good warm up and 10 min run, it comes down to normal idle rpm now.

Thanks, everybody that posted with any suggestions. If two heads are better than one, a whole forum can solve just about anything. Thanks!

 

[flybars]

I'm glad it was such a simple remedy. I learned something very valuable here. Thanks.