KX Riders
Maintenance & Technical => KX500 Original => Topic started by: Spencer-VDTRA on February 21, 2011, 08:44:51 AM
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The other day, when I went riding with my friend Joey, and Stewart Rouse of KX5 Power, my bike was acting up a bit... And just about killed me. After getting it warmed up, the engine revved up by itself as if someone was pinning the throttle for me. I stalled it to kill the engine.... Took the carbuerator apart, cleaned it, figure it was just running out of gas due to a stuck float, put it back together and ran it again... 45 minutes into riding it, it did it again..while cruising in 3rd gear. Front wheel lifted up, back tire spinning, and me pointing in the wrong direction. I had to slam the back brake, click up to 5th gear and pray that it shut off before I did more damage.... It took a minute, but it eventually died. When I brought it back home, I checked the throttle cable... I just bought it last summer. No kinks, no frayed ends, nothing snagging it, looked fine. I know when a big bore bike such as the KX500 runs out of gas, it revvs up a bit at a slower pace that pinning the throttle, but it was revvin' out of control and it didn't want to stop.
Has this happened to anyone this before? And does any of you have an idea what the problem could be and how to fix it? It's making me nervous to think that I could go through that horrible nightmare again. The last thing anyone wants is a 500 revvin' out of control.
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First and foremost, where is your kill switch? secondly, check your carb slide, I have heard of worn out slides getting stuck in the carb bore, and I have also heard of the slide getting stuck up in the cap.
Get a kill switch, not soon but now! And check the carb again. Stewart should have plenty of parts at his shop to help you out, and from what I hear he is a hell of a guy.
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Let's just say the killswitch didn't do it's job. On the bottom end, it works... As it should. But when you revv it up, it doesn't work as effectively. But the slide looked fine... The throttle was completely closed when this problem happened. I was completely off the throttle, both times.
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Base gasket. Its suckin' air or the slide is hangin'. Look close at the base gasket for dampness or clean spots on dusty cylinder. Base Nuts maybe loose. Can be running out of gas with a clogged petcock or other blockage, but its not as scary as when you have a base gasket leak. I have heard of bad seals sucking air too, but not sure if it would suck that much.
Pucker Power :lol:
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As mentioned check your slide and cable again, also look for air leaks around the intake boot and base gasket. 9 times out of 10 if your bike is revving uncontrollably, lift your choke and it will drown out the motor.I've seen people try turning off the fuel or jamming it in gear with only more probablems, use the choke!
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Let's just say the killswitch didn't do it's job. On the bottom end, it works... As it should. But when you revv it up, it doesn't work as effectively. But the slide looked fine... The throttle was completely closed when this problem happened. I was completely off the throttle, both times.
If the killswitch didnt do its job.... this tells me AIR LEAK... or LACK OF FUEL.. Leaning out to the point of self ignition...
Stewart's stilll alive and kicking huh?
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Has anyone tried one of those kill switches like the flat track guys use? Basically the button is up for run and just push for stop. They are not momentary switches like the stock kill switch.
Fitz
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Has anyone tried one of those kill switches like the flat track guys use? Basically the button is up for run and just push for stop. They are not momentary switches like the stock kill switch.
Fitz
Wouldn't have helped in this situation. As it was auto ignition time due to lean....
But yes my k5 is kind of set up this way.. I run a baja designs kit on it.. And their setup has a momentary kill on it.. BUT the light switch has to be on to make the ignition hot.. So if you just shut off the light switch. It kills the ignition 100%..
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Hi guys,
Could a hole in the resonator case also have caused this?
I'm having the same problem :-(
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Well, during my teardown, I did discover something..
A massive 5" crack on my expansion chamber, right along the weld of the frame bracket.
Possible cause for the bike to lean out?
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Has anyone tried one of those kill switches like the flat track guys use? Basically the button is up for run and just push for stop. They are not momentary switches like the stock kill switch.
Fitz
Most flat trackers either use a compression release that went in the other spark plug hole, or the old ignition switches that came on the motocross bike. Back then, they just had an Off-On switch.
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Well, during my teardown, I did discover something..
A massive 5" crack on my expansion chamber, right along the weld of the frame bracket.
Possible cause for the bike to lean out?
Long answer... Yes..
Short answer.. Yup..
Lean out how yours was... Nope... your lean out issue was UPstream... In my oppinoin
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Well, during my teardown, I did discover something..
A massive 5" crack on my expansion chamber, right along the weld of the frame bracket.
Possible cause for the bike to lean out?
Long answer... Yes..
Short answer.. Yup..
Lean out how yours was... Nope... your lean out issue was UPstream...
You got my hopes up. Hahaha!
Well, the base gasket is fine..
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did you do a leak down test yet?
crank seals, intake, etc are still on the list
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did you do a leak down test yet?
crank seals, intake, etc are still on the list
Intake, yes, ignition/clutch covers, yes, cylinder head, yes.
Bottom end... Ummmm... No. That part of the operation is what's scaring me.
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did you do a leak down test yet?
crank seals, intake, etc are still on the list
Intake, yes, ignition/clutch covers, yes, cylinder head, yes.
Bottom end... Ummmm... No. That part of the operation is what's scaring me.
Good old stewart has the equipment to do this leakdown properly... You should ask him really nice, (offer to buy him lunch) that works in our shop... along with a case of beer.
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I had this happen on my KDX200 a few years ago. Stuck at full throttle while in top gear riding at the river! It had quite a bit of work done to motor too. I'd hate to have it happen on a 500. I held the kill switch in but it took a long time to stop it. Turned out the throttle cable was about to snap, there was some small bits of frayed cable that had fallen off and got stuck beside the slide.
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First make sure slide didn't stick.do not put lubeon the slide as it wil gum up and hang. Second spray. Carb cleaner forward toward the jug (away groom air box)while it is running. To see if it revs up. Look for intake. Leaks. Base gasket or main seal under stator cover or even the clutch cover. They can suck air and oil from the clutch side. Also a broken reed. I would co it afterthe slide cleaning.