Shut petcock while ideling ...

[Crankshaft396]

Hello To All , I just was putting around on my K5 and decided to shut the petcock and let the carb run dry and I noticed the RPM's starting climbing higher and higher !! It reached a point where it started scaring me a little and I hit the Kill switch ... why does it do this ?? Is this normal ?? This is the second time it's happened ... Thanks for your help !! Tim

[Foxx4Beaver]

Yeah don't do that anymore....what happens is its leaning itself out, starving for fuel...sucking more air than anything.
When you wanna drain the carb, just pull the 17mm bolt off the bottom of the bowl...that'll get most of it. If you take the carb off, there'll still be a little inside, which you can get out by just rotating it in your hand....or with carefully with compressed air.

[Crankshaft396]

Thanks Foxx4Beaver , I'll be sure when I'm done riding to just hit the Kill switch ... Thanks again Brother !!

[streetsleeper]

Crankshaft396
Newbie

 Offline

Joined: 06.14.13
Posts: 3


   

Shut petcock while ideling ...
« on: October 09, 2018, 01:51:52 PM »
Quote

Hello To All , I just was putting around on my K5 and decided to shut the petcock and let the carb run dry and I noticed the RPM's starting climbing higher and higher !! It reached a point where it started scaring me a little and I hit the Kill switch ... why does it do this ?? Is this normal ?? This is the second time it's happened ... Thanks for your help !! Tim

Hallo mate,
Just thought I'd chime in on this one. There's a video on YouTube from a guy who has his own channel - called LUND MX. He starts his KX500 (an '87 model like mine) for the first time and the revs rise to an alarming rate. He hits the kill switch and nothing happens.
Well, the exact same thing happened to me. The first time the bike has been started for perhaps ten years. The carb - a Mikuni 38mm which was a one off for the Kawasaki KX500 around that year - ran dry. As the float chamber drained and the venturi continued to suck the engine went haywire. The revs rose and rose and even the kill switch didn't do its job. I pulled the suppressor cap off the plug in order to kill it. Poor thing!
So you're definitely not alone on that one Tim. No damage done, just WOT for a few secs (but seemed like an eternity!).

[kxpegger]

I ride desert and usually turn the gas off about 1/4 mile from the truck to lower the gas level in the bowl so when I load the bike and lean it over to the side to get the tailgate closed it doesn't piss fuel in my truck bed. Probably not the best practice but it works for me. I never let it get to a point where it's leaning the engine out though. The better option for me might be to turn the gas off and lean the bike over to drain the excess gas out when I'm at the truck instead but that's an extra step and I'm lazy. You'll notice that if your bike has been sitting for awhile it will rev high for a few seconds after you start it if the gas was not drained from the carburetor. This is because the gas evaporates and leaves the pre-mix oil behind. When you turn the gas on it will mix with the left over oil but will also cause a lean condition. If I haven't ridden mine for awhile I will turn the gas on and let the left over pre-mix oil mix with the fresh fuel. I then turn the gas off and lean the bike over to drain all the old crap out and start the bike.   

[1901306708]

if your kill switch wont work you are likely dieseling.

mine has done this a couple times when trying to increase my ignition timing. more octane or less ignition advance fixed that issue for me.

[Al in MI]

I've thought that hauling a bike with the bowl empty causes the float to bounce around when underway.

On the subject of the kill switch not working when the engine is screaming : The kill switch works by grounding the ignition coil (a step up transformer) primary.  Since the kill switch is not right at the coil there is a length of wire involved, maybe a foot or two (wire has resistance so the further from the ground connection the higher the voltage). When the engine is near idle the small voltage on that foot or so doesn't matter and the kill switch effectively shunts the primary to ground and the coil secondary (spark) is near zero and not enough to fire the engine.  BUT, when the engine is screaming there is enough voltage on that wire even though it is grounded at one end & the foot or so of wire to permit enough voltage at the spark to keep firing the plug.  Pulling the plug wire will kill it but you could get quite a zap yourself.  Another proven way to kill a runaway engine is to block off the exhaust, use your boot I never tried a glove.