Why does it stall

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May 30, 2003
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#1
Here's a question that is so simple, you must know the answer. But I don't.

I installed a Boeyeson Rad Valve and FMF system on my KDX220R. I went from a 145 stock main jet down to a 138.

It starts fine, idles fines, revs fine ---except:

It stall when the throttle closes. This can be a real bitch on a single track downhill into a turn.

I'm sure that its some simple little thing that you've seen before, like needle height, or pilot jet or whatnot.

If you have seen this with these mods, please let me know. Thanks.

Andrew
 
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#2
I saw this with my friends cr250. He put in some delta force II's(i think) and set the tension to high. He didn't change the jetting. Next thing you know, I'm behind him an a single track and after a long(and fast)sandy sweeper, it's choice time----hit some nice pines trees, hit him, OR lock 'em up and lay it down before hitting anything. Needless to say, laying it down was the best choice---my first wreck since coming out of retirement a couple months ago, complete w/ one heck of hip pointer. His reed tension is adjustable and low may be the way to go. Don't know if yours is or not. I don't know the solution, but am quite interested to find out what it is. I don't tailgate my buddy anymore!!
Just didn't want you to think your the only one with this issue.
Good Luck.
 
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#3
Adjustable reed tension on Boyeson Rad valves?? Okay, I'll look.

Doesn't seem like the air screw changes things much; which, I suppose, is a good indication that things are out of whack on the bottom. I had assumed, hastily, that is was a fuel, not an air issue. It starts and idles fine, though. It just stalls when the throttle is closed.

Thanks, I'll have a look.
 
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#4
You might try checking your pilot via the airscrew method. If it's right, maybe you should bump up the idle and make sure to pull in the clutch when braking really hard. Probably wouldn't hurt to do a thorough carb cleaning as well. Let us know how you solve this one. Surprising there's not more info on the web about this condition---I'll bet it's fairly common.
 
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#5
I don't think that the Boyesons are adjustable. So, the next best bet is the pilot.

No chance of dirty carbs -- its a brand new bike. And belive me, its not my clutch technique, its the intake system -- and sorting out the mods.
 
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#6
Does the bike start easy?
At steady throttle IE 1/2 are you getting any surging?
At idle is it surging , going up or down?
Please check the intake side for leaks, sometimes when doing the reeds something might be loose. Iknow this sounds basic but it happens to everyone.
If the bike is shutting off when coming down to an idle it is either rich or lean.Try adjustments with the airscrew from 1 to 2 turns out.
Chances are with the leaner main you might be lean on idle, if the air screw can't compensate go up one size at a time on the pilot.
BTW did you have to change your needle setting?(dropped it a notch?)
How does your plug look compared to stock?
Lots of work but its all worth it. It took me months to get my KTM sorted out.That bike was a tempermental pig in all senses, now it runs fine.

Good Luck(jetting sucks)