No Spark Problem

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May 29, 2007
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#1
Hey guys, I was riding my KX500 and it lost power. I could only keep the bike running for maybe 200 yards with the throttle just barely open and then it stalled. I kicked it a few times and it tried to start,but wouldn't. I pulled the plug to check for fire and nothing. I swapped the plug and held it against a head bolt to check for fire and still nothing. Anybody got any ideas?
 
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May 1, 2007
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#2
same thing happened to my quad. get a manual and start checking the electrical components. On my quad it was the coil fried. Could also be the stator, pickup coil, CDI. Spend a little time with a manual and an ohm meter, you'll get it.
 
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#3
I got the bike to run, but it will only idle. When I go to crack the throttle open it wants to die. If I open the throttle slowly it tries to rev up, and this is with the throttle just barely open. I checked the compression and it's at 125#s and the carb is also clean. Would a broken reed make the bike run like it is now?
 
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#4
125 psi? whats pretty low for compression. A good top end for a 125cc bike should be up near 180psi. Im not sure what it should be for a kx500, id imagine it be alot higher.
 
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#6
That reed petal could be floating around in the crankcase right now. It might be wise to pull the cylinder and have a look.
 
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#7
That's what I was thinking 76GMC1500, but I don't want to. I want to ride this thing now, maybe I got lucky and it got blown out the pipe.
 
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#9
Maybe you'll get unlucky and it will trash the cylinder on its way out. How about your no spark problem? That seems unrelated to the reed. I've had spark plugs arc deep inside and not at the gap so it appears they don't spark. When that happens my bike ran EXACTLY as you described. That was fouling caused by an improperly installed right side crankshaft seal.

It only takes a day to remove the cylinder, blow the reed petal out of the crankcase with compressed air, and reinstall. It should cost you a reed block gasket, head gasket, and base gasket (<$20).
 
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#10
I don't know about the Kawasakis, but I can pull the cylinder on my CR250 without removing the head. The base gasket can be reused if in good condition. So, I can pull the cylinder without buying or waiting for parts. I've pulled and reinstalled a cylinder in 2 hours once.
 
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#11
76GMC1500 said:
I don't know about the Kawasakis, but I can pull the cylinder on my CR250 without removing the head.
How do you do that? :think:

Must be one of those new fangled 2 piece cylinders! :laugh:

Rotor
 
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#12
I undo the 4 nuts at the bottom and lift the cylinder off the case. It's really that simple. The power valve linkage is operated by a cam so there is no connection that has to be undone. To reinstall, the right side cover does have to be removed to disengage the powervalve governor from the cam and rod. My only Kawasaki experience was an 88 250. The head had to be removed to acesss and time the power valves. Therefor, the head has to be removed in order to be able to install the cylinder.
 
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#13
Hey 76GMC1500, I put the stock reed cage back in and I guess I did get lucky, the bike runs great. The guy I got it from said it should be fine, but I was thinking the same as you were. The spark problem is still got me puzzled. How can I tell if it's a crankshaft seal problem, just ride it and wait?