Author Topic: Revvin' out of control! TOO FAST!  (Read 6168 times)

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Offline Spencer-VDTRA

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Revvin' out of control! TOO FAST!
« on: February 21, 2011, 08:44:51 AM »
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.

Offline suicyde

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Re: Revvin' out of control! TOO FAST!
« Reply #1 on: February 21, 2011, 08:54:45 AM »
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.

Offline Spencer-VDTRA

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Re: Revvin' out of control! TOO FAST!
« Reply #2 on: February 21, 2011, 09:02:00 AM »
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.

Offline Hillclimb#42

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Re: Revvin' out of control! TOO FAST!
« Reply #3 on: February 21, 2011, 09:14:09 AM »
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:

Offline RoostDaddy

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Re: Revvin' out of control! TOO FAST!
« Reply #4 on: February 21, 2011, 12:20:21 PM »
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!
America is all about speed. Hot, nasty, bad-ass speed.

Motorrad

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Re: Revvin' out of control! TOO FAST!
« Reply #5 on: February 21, 2011, 05:02:32 PM »
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? 

Offline flyingfitz

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Re: Revvin' out of control! TOO FAST!
« Reply #6 on: February 26, 2011, 07:41:23 AM »
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

Motorrad

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Re: Revvin' out of control! TOO FAST!
« Reply #7 on: February 26, 2011, 11:38:17 AM »
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%..

Offline Koosie

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Re: Revvin' out of control! TOO FAST!
« Reply #8 on: March 02, 2011, 09:49:17 AM »
Hi guys,

Could a hole in the resonator case also have caused this?

I'm having the same problem  :-(

Offline Spencer-VDTRA

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Re: Revvin' out of control! TOO FAST!
« Reply #9 on: March 05, 2011, 02:05:00 PM »
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?

Offline Spencer-VDTRA

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Re: Revvin' out of control! TOO FAST!
« Reply #10 on: March 06, 2011, 03:54:15 PM »
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.

Motorrad

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Re: Revvin' out of control! TOO FAST!
« Reply #11 on: March 06, 2011, 04:04:26 PM »
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

« Last Edit: March 06, 2011, 05:10:54 PM by Motorrad »

Offline Spencer-VDTRA

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Re: Revvin' out of control! TOO FAST!
« Reply #12 on: March 06, 2011, 04:12:19 PM »
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..

Motorrad

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Re: Revvin' out of control! TOO FAST!
« Reply #13 on: March 06, 2011, 04:17:50 PM »
did you do a leak down test yet?

crank seals, intake, etc are still on the list


Offline Spencer-VDTRA

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Re: Revvin' out of control! TOO FAST!
« Reply #14 on: March 06, 2011, 05:07:00 PM »
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.