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Enduro Intake/Carburetion - 2 stroke Jetting, Reeds, Air Filters, etc. |
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#1
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EC300 Idle Revisited.
OK guys, I'm ready to throw this POS carb in the trash. I've got the same issue he does: http://www.gasgasrider.org/forum/sho...highlight=idle
There is utterly no way I can get a consistent idle. If you even touch the idle air screw the bike will idle extremely high or almost not at all. This is not a needle, MJ, PJ, air leak or float issue. There is something fundamentally wrong with this carb. Surely somebody has figured out what to modify or what carb from another bike will properly work. The similar carb works perfectly on KTMs, why would it not on this bike? I don't buy for a second it's squish or head design, there is some kind of fueling issue that causing the carb to radically change AF with a very slight adjustment. Is there a definitive answer for this carb or what's a good replacement? I thought I was very good with carb tuning and I have it working perfectly except for this one issue. Thanks.
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04 Montesa 315R, 07 EC300, 21 KTM Erzberg 300, 21 Sherco 300 SEF-F, 23 KTM 690, 23 Rieju Mr Pro 300 |
#2
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My bikes idle and carburate perfectly I'm guessing you have to rich of a slide. Try a #9 cutaway with a 35 pilot.The smaller cutaways have to much velocity over the pilot circuit.
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#3
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Mine will idle forever leaning on a tree. However, I have seen a Keihin PWK38 on a KTM 300 with some casting flashing on the nozzle, and that bike was always a bitch to jet. Check that out and clean it up if present.
What else are you going to do for a carb? The Mikuni is a more of a PIA, we swapped it for the Keihin on my brother's Husky last year and never looked back. If all else fails, call Ron at RBD. |
#4
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I really hate to mess with the slide. Everything right off idle seems to be perfect.
One of my friends mentioned something about notching the slide. Currently I'm running a #7 but I tried a #8 with no noticeable results. What's driving me crazy is absolutely nothing I've done has had any real effect. Every other 2T I've ever had with this family of carbs has been fine. I swear this thing is almost as bad as the old Bings except it doesn't leak.
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04 Montesa 315R, 07 EC300, 21 KTM Erzberg 300, 21 Sherco 300 SEF-F, 23 KTM 690, 23 Rieju Mr Pro 300 |
#5
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You could go to a Mikuni the tunability and tech support is outstanding but they are somewhat more complex as your now adding another system component ,the needle jet. You could prob pick up a vm38 round slide which is kind of old school but works very well for our applications and there a lots of snowmobile tuning manuals available for that carb. I pulled one off of a 92 wr 250, bored it to 39 mm and put it on a 94 cr 500 where it worked flawlessly with a big scary top end gain.
Last edited by widebear; 09-27-2009 at 08:13 PM. |
#6
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Didn't Yamaha or Kawasaki have a notched #7 on one of their motocrossers?
Might be worth a try.
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04 Montesa 315R, 07 EC300, 21 KTM Erzberg 300, 21 Sherco 300 SEF-F, 23 KTM 690, 23 Rieju Mr Pro 300 |
#7
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Thousands of bikes run fine with this carb, its something with your particular specmin. Look for the problem in the carb rather than reinvent the wheel.
The idle circuit is very small, perhaps it is partially blocked by debris or flashing, or perhaps the casting is defective. Can you try ot on another bike? 300s most always prefer the #8 slide over the #7. |
#8
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This might be totally non applicable, BUT I have noticed that when I adjust the idle air screw, it effects the spark plug. Sometimes it just fouls it out and the bike dies. Sometimes, what is even worse then a dead bike, is it starts running very erratic and strange, almost to the point you think there are some major issues.
Again, dont know if this helps, but thought it might. gasgasdreamer
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2002 Husberg FE650e 2006 GasGas EC300 2014 Sherco SER300 2014 Beta Evo Factory 300 |
#9
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Another thought.... Is your idle adjustment screw the plastic one or a brass one?
I had the plastic idle screw get hammered flat on one side from the slide being dropped on it over time. Or maybe someone in camp kept snapping the throttle when I was not looking....?!?!?? The bike would barely idle. If you turn the screw maybe 1/4 turn it would rev up big time. Keep turning for a full turn and it would barely idle again. I replaced the screw and problem fixed. Worth the 5 min. to check. Jeff |
#10
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Where did you get a brass screw?
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04 Montesa 315R, 07 EC300, 21 KTM Erzberg 300, 21 Sherco 300 SEF-F, 23 KTM 690, 23 Rieju Mr Pro 300 |
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