WTF did I do?

N

nokturnal

Member
Quick intro -- this is my first gasser and first real dirtbike (06 EC250). Previously I have had quite a number of 2Ts, but all were on the street. I bought a DR650 and took to the trails... you know how that ended up. Now I have a gasgas.

I took it for a spin when I was looking at it, and it ran great. Like a scalded cat. The only thing was that it idled a bit high (done lots of searches on that), about 2200rpm. Idle screw seemed to do nothing. Choke made the engine race.

I took the carba apart suspecting a clogged pilot circuit, nothing. Cleaned it all anyway and reassembled. Still had a high idle. I noticed that it would drop to a reasonable level with a combination of blipping and airscrew work, best was one turn out, but it would not "stick". If I blipped the throttle, back would come the high idle. !?! stuck throttle cable! I turn the bars and the bike races... ok done. I took the cable off off the handle, and rerouted the cable making sure all was loosey goosey, lubed it too. Nice and smooth. All done I thought...

NOW the thing will not even idle, high or not. I have to keep blipping it to keep it running. Nothing I do with the air screw or idle screw will make it tick over. :eek:

:confused:

I did notice that when I took the bar assembly apart that I heard the slide "thud" down, when I removed the white pully.

Since I have been out to the garage I have been thinking... Does the cable adjuster at the bar need to lift the slide slightly to make it run? Is that not what the idle screw is for??? lol

Any suggestions would be greatly appreciated. Sorry for the long post.
 
You're correct in your assumption. The idle screw is used to lift the slide and you should be able to visibly see this if you have the carb out, or peak in the airboot with the filter off. From here its all about the right mix or fuel and air. Lifting the slide up further lets more air in creating a leaner environment so a richer pilot works. If you've dropped the slide down odds are that the pilot is too rich. Try turning the AS out half a turn at a time until you get an idle. If you come out 3 turns move a size smaller on the pilot and start again at 1.5 turns on the Air screw.
 
So... the choke making the engine race BEFORE rerouting the cable was probably just a fluke (because the slide was up) and the pilot is in fact actually rich? hmmm

AS has zero effect right now. NOTHING i do with the idle screw or AS will do anything really...

I am running 180/45 not sure on the needle at the moment.



Something else interesting I noticed with my first PWK. There is no o-ring on the AS. All my previous carbs (Mikunis) have had o-rings on the air screws. I thought this might have been my issue, but looking at the fiche, there is no o-ring...
 
I've never had the air screw right out of mine, but have noticed a bit of oily residue come from it at times. A quick search shows lots of drama with the air screw having little effect on these bikes and inconsitant idles. Alot seems to be related to excess squish clearance.

The needle diameter will have a large influence over what size pilot the bike requires so its hard to just say yay/nay without all the info. Lifting the slide up higher by using the idle screw you should be able to get the bike to idle again, however you will probably run back into the problem you faced before. Either an idle that hangs high after a blip of the throttle, or flames out by a rich condition. I personally think the inconsistancies are caused by excessive squish height and fuel load being trapped under it. Alot of info supports this theory as people who have had head mods find the bike much more stable and easier to jet. I'm betting yours is running the stock head too :)

I have posted a few different threads back when I was chasing my tail where I'd go from no idle to racing idle all within about 1/4 of a turn of the air screw. Very sensitive circuit.
 
Cool, thanks.

Yes, planning on doing the head mod this coming winter when I do the top-end. Just need it to run until then! ;)

Gotta love the smokers. Always an adventure...
 
Probably not what you want to hear, but I'd suggest setting the slide so its just lifted visible. Set the AS at 1.5 out, and then shuffle through the pilot jets until you get one that idles. You will find the magic mix, its just trial and error.
 
so maybe I spoke too soon... it seems I can make it idle. When I blip it, it will hang at 2-3k for a couple of seconds before dropping to ~1000rpm.

AS at 2.5 out, Idle screw almost all the way in. It still races on choke.

Pilot is 45 now. Drop to a 42? (40?) Maybe I will buy both...
 
Which Needle?

Did you get a needle code yet? The experts will need your total set-up.

Pilot: 45
Main: 180
Needle: ?
Clip down from the top: ?
Altitude: ?
Average temp: ?
Dry or Humid?

With all the info someone can get you close.

I can vouch for the vastly more consistent powerband with the correct squish.
 
nokturnal said:
so maybe I spoke too soon... it seems I can make it idle. When I blip it, it will hang at 2-3k for a couple of seconds before dropping to ~1000rpm.

AS at 2.5 out, Idle screw almost all the way in. It still races on choke.

Pilot is 45 now. Drop to a 42? (40?) Maybe I will buy both...
Click to expand...

Have you checked the condition of the reeds? Could give idle problems.
 
Its true that you will do nothing but chase your own tail if the engine isn't mechanically in the right condition to start with. Ideally you'd want a fresh top end, new reeds, and a clean carb. Not everyone wants to replace everything just to make some changes, but its still worth youre while to check the condition of whats in there. You can peek at the piston through the exhaust and intake and should check the reeds for chips. Then as Ando said you need to give all the info including needle code (i think this is the biggest part of the puzzle).

By you having the idle screw wound all the way in you're telling me you are way too rich on the pilot ciruit and have essentially by passed it by lifting the slide to the point that you go onto the needle taper. Now you need to find out why you're rich. Is it broken reeds, or a really rich needle diameter matched with a big pilot.
 
Thanks guys.

I am going to try the pilot first.

The bike is pretty nice, very good original shape with <1000miles on it (it shows). Hopefully it is as good inside as it is out, and it is the fat squish that is pushing me around. I will get the head done after the season is over.
 
nokturnal said:
Thanks guys.

I am going to try the pilot first.

The bike is pretty nice, very good original shape with <1000miles on it (it shows). Hopefully it is as good inside as it is out, and it is the fat squish that is pushing me around. I will get the head done after the season is over.
Click to expand...

you can put a thinner base gasket to up the compression if you don't want to loose to much time right now :)

and the fact of not idling ,i my case it was even the stator plate that was not set right (still don't really know how to set it right, but i adjusted it till i got a bike idling ok...
 
Jakobi said:
I personally think the inconsistancies are caused by excessive squish height and fuel load being trapped under it. Alot of info supports this theory as people who have had head mods find the bike much more stable and easier to jet. . . .

. . . . I was chasing my tail where I'd go from no idle to racing idle all within about 1/4 of a turn of the air screw. Very sensitive circuit.
Click to expand...
Yep hard to say which one but my a/s actually works now that I've had the head (and carb) mods done. I no longer have the hanging/racing idle thing going on. Prior to that I was wasting my time trying to jet the idle.
 
Is there a chance you have a leaky crank seal on the mag side or an air leak on the fuel side of the motor? Could be a base gasket, crank seal, or carb intake boot. I would check for an excessive lean condition. I would start by spraying the base gasket area with carb cleaner while the bike is at the most normal idle you can get it at. Listen for the bike to increase RPM's, (simulates turning the choke on with an air leak). If that happens you have a bad base gasket. If that does not show any results you can remove the mag side cover and spray behind the flywheel. You can also look for sticky oil deposits near the mag side crank seal, which would show a bad crank seal. Pretty rare, but the carb boot, (between the carb and cylinder) may be leaking. You can also check that with carb cleaner. Just a thought, hope you have a carburation issue that is resolved cheap.
 
Maybe.. You'll spend your life trying to chase your tail jetting an engine thats not in good mechanical condition..

Hope you can get it all sorted in time to get some riding done!
 
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