Wandering airscrew?

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johnyblaze
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Wandering airscrew?

Post by johnyblaze »

Anybody else have a wandering airscrew? I noticed a few days ago my 220 was bogging right off idle. Checked the airscrew and found it was about 4 turns out. Thought I must have inadvertently hit it while putting new fuel line on. Set it back to 1.5 turns out and it ripped again. Wheelies 1-4.

Took it out yesterday for about an hour - seemed to be OK but when I cleaned her off this am and took it for a rip through the woods it was bogging again. Sure enough the airscrew is at 4 turns out again even though I didn't touch it.

I've also noticed she's idling higher than normal lately so I'm about ready to pull the carb and check the jets.

Anybody else have a wandering airscrew?

98 220 with Fredette carb bore to 35mm, FMF burly pipe with stock silencer. Boyesen reeds - but I'm not sure which.

Thanks in advance.
808hondacrguy
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Post by 808hondacrguy »

Do you still have the spring in place that holds the tension on the airscrew?
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RBD
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Post by RBD »

>|<>QBB<
808hondacrguy wrote:Do you still have the spring in place that holds the tension on the airscrew?
I second that!

Ron
johnyblaze
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Post by johnyblaze »

Ya, first thing I checked as well. Spring is in place.
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Post by johnyblaze »

I'm wondering if it's the high idle that's moving the airscrew around? I started it this afternoon and the idle was probably between 2000 and 2500 rpm - about where I'd set the choke to warm it up. The idle barely drops when I release the choke knob. Checked the throttle cable to see if it or the tube might be hanging up - no such luck.

Looks like the carb's definitely coming off for a cleaning. I've been thinking hard about sending the carb (and head) out to RBD but wonder how much it would improve over the Fredette 36mm bore. It's already pretty gnarly down low, so I'm wondering if I'd gain much. Pretty sure it'd come back jetted correctly, though.
1998 KDX220 with goodies
2002 KTM LC4E
2001 Suzuki Bandit 1200S
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scheckaet
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Post by scheckaet »

i would soak the carb overnight and clean the jets really well.
Is your air screw spring broken / worn out? maybe not enough tension to keep it from wandering?
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Colorado Mike
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Post by Colorado Mike »

re: "...so I'm wondering if I'd gain much..."

On a 220? Oh yeah. The head mod will do wonders. The divider plate is a huge improvement too. It makes bike work much better at partial throttle openings.

Oh, and that high of an idle is scary, you sure you don't have an air leak? looked down the throat and made sure the throttle is closing?
Mike

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'04 KDX220
johnyblaze
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Post by johnyblaze »

No - not sure I don't have an air leak. I made sure the fore and aft clamps were tight and even tried to wiggle the carb back and forth to see if it increased or decreased the idle. No changes.

Guess I was hoping this would be one of those headaches that suddenly disappears as quickly as it came. Hasn't happened yet. That carbs coming off. At least it looks like an easy one to pull. My 4-stroke carbs are always buried deep within the bowels.. KDX carb removal looks positively simple in comparison.

Sheckaet - I'll try cleaning it in pinesol like I read a couple weeks ago.

Colorado Mike - the bike's already got a lot on bottom. I still think it lacks in mid and top so that's where I'd be looking for help. Wouldn't the divider plate just add down low? Remember, the PO had it bored to 36mm at Fredette Racing. I'm sure the squish band helps all over though.

Hey, it just occurred to me - the idle wasn't high until I changed from the FMF silencer back to th stocker. Is it possible that an air leak around the exhaust somewhere would cause the idle to go ballistic? I can't imagine the silencer change would have necessitated jetting changes to run right. Maybe for grins I'll throw the FMF back on to see what happens before cleaning the carb.
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Post by Colorado Mike »

It's a 220, of course it lacks on top. Assuming you already have the rev pipe, the only thing that will really wake up the top is porting. Ron's head work makes the torque much fatter. I would recommend you forget about top end and enjoy short shifting. no reason to rev a 220 in my opinion, at least at the 9-12,000' I normally ride at. If you want rev, it's probably cheaper to find a 200 jug, piston and head.

I think if your throttle is closing all the way and you have a 2K rpm high idle, you have an air leak, possibly in your crank seals. I may be wrong, but it's important to rule that out before you blow the motor. You can build a simple leak-down tester for under $20 with parts from Deep Homo to test this and set your mind at ease.
Mike

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'04 KDX220
johnyblaze
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Post by johnyblaze »

Leakdown test showed all is well in KDX land. I pulled the carb, soaked it, blew it out and reinstalled. All is well now - idling like a champ, but I don't know what actually happened.

Guess if it ever happens again I'll just pull the carb and clean it. Easy enough fix.

Thanks for the info and help.
1998 KDX220 with goodies
2002 KTM LC4E
2001 Suzuki Bandit 1200S
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