KDX 220 - jetting anomaly

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mtnickel
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KDX 220 - jetting anomaly

Post by mtnickel »

Hi guys,
Thought i'd ask the experts on a problem i'm having with my bike.

I've got a 98 kdx 220. Desert Pipe and stock 145/42. Needle in top clip.

When I bought the bike it ran "ok". good power up top, a tiny bit of a lean bog if WOT from a very low RPM. Otherwise decent.

Over the course of maybe 10 hours of riding, the idle seemed to diminish a little. (would die periodically). Moreover, the light throttle was spotty.

Ok, so I read up on all the jetting issues and definitely suspected the carb. Turned up the idle a bit, and backed out the AS and it ran much better for a while.

The idle was not very good still though and cruising resulted in burbles (throttle seemed to be either on or off).

So more troubleshooting led me to the reeds. I in fact had a small chipped corner off a reed (boyesen stock replacements). About 3mm X 3mm corner. NOt sure how much this affects driveabillity.

So I replaced the reeds with power reeds. Then I ventured to reset the jetting since the reeds are new.
Put needle in second clip as recommended with 40/145.

Bike would not idle unless AS way out. Dropped to a 38, and idle still does not respond well to screw...needs to be 3 turns out. This just seems wrong. Moreover, did a plug chop and it was barely any color! :| went up to 148 and still not much colour on electrode. Power does feel good though (but i'm sure it would running lean).

Anyways, this is where I stand and am frankly a little baffled. This is my first bike, but i'm a pretty good mechanic (car wise), and have done a reasonable amount of reading trying to educate myself.

Bike runs right around sea level, and about 18*C. I adjusted float using parallel method and double checked as close as i could with measuring. should be close, though I coudln't verify.

Should I continue to drop my Pilot and increase my Main? This just seems wrong. Any mechanical issues that would cause such symptoms? Compression seems good as power usually is as well. Any help would be greatly appreciated!
KarlP
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Post by KarlP »

A 148 main seems awfully big under those conditions.

Just for the fun of it, try 140/38 with clip in 3rd from top of of needle and snorkle removed from air box cover.(carefully! There may be something else at play here!) See if your AS responds then.

It's not you air cleaner getting dirty, is it?
Some "burbling" is entirely normal.
'08 KTM200xc
'99 CR/KDX Hybrid with that RB stuff done to it
KX100 for the boy
mtnickel
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Post by mtnickel »

wouldn't the plug chop (no color) be reason NOT to go smaller on the MJ?

I'd hate to melt a piston. I suppose this test could be done to check the idle. I was under the impression that the MJ didn't do much at idle.
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rbates9
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Post by rbates9 »

Stock should be 160 main and 48 pilot. Maybe you should start there. I have found that a 42 pilot and 155 main seems to work good for me at 1000 Ft or so. It wouldn't hurt to try a set of brand new jets also and make sure the carb is very clean, take every thing out of it and clean every passage and orifice. There is also a "jetting guide" on here that should help you out alot.
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