Maintenance & Technical > KX500 Original

HELP Hard to start, I've tried everything!!

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dean350b:
Okay, rebuilt the top-end of the 1987 KX500C-1:

New piston & rings, clearances perfect, LOTS of compression.

New KIPS valves timed correctly.

Everything spotless, carb, airbox, pipe, you name it, its been cleaned and assembled correctly.

Cleaned the UNI air filter and lightly oiled it with 30wt engine oil.

New spark plug, correct one. Gapped at .025

Ohm Tested coil = good

Ohm Tested CDI = good

Ohm Tested Stator windings = good

Removed flywheel = perfect /keyway aligned/not slipping.

Removed stator plate, cleaned everything for perfect ground.

Keihin PWK with 168 main / 55 pilot / Screw out 1-1/2 / 2nd clip on needle. (tried many settings)

Idle screw set to many different settings, makes no difference.

Brand new Boysen SuperStock reed valves. New gaskets.

Float height set to 16mm.

Fresh 92 gas at 36:1 Castrol A747

Will only start if I pull the bike with a rope and a truck, engage he clutch in 5th gear she will fire in approx. 1/8 mile of pulling. She will then run, but really boggy & poorly. Feels like it is missing, etc.

Runs crappy. Cannot adjust anything on the carb to make it idle, but I guess you can say it does run???If I rev the engine, it does rev well, but will not idle at all, and tries to die if not always holding the trottle open somewhat.

Is not "crisp" at all.

Biggest problem is: Stop bike, try to start with kickstarter: All I get is massive (LOUD!!) backfires out the tailpipe every 10 or 15 kicks, but will not run.

Tried every starting technique on this website and some of my own, lay bike over, flood it, fuel pouring out tubes, etc. Nothing.

Any advice???

KX5Zuki:
Hows your timing? Since you took the stator plate off, you might have put it back on in the wrong timing marks for a fairly stock motor. Even mine, since I coulnt kick it for the life of me, started up fine with a pull of only about 5 feet. Just a few rotations of the motor. Check your timing first. Leak test it as well.

dean350b:
Timing is lined up exactly on the center timing mark like the factory manual shows.

Does the leak test verify the crankshaft lip seals are not passing compression into the gearbox?

KXcam22:
That sounds like a timing issue. It is likely that your CDI box is crapping out.  You get good spark but the CDI timing is too far off to start.  Ohm test verifies that the CDI is not blown but doesn't indicate if it's working correctly (ie spark delayed in time). I would put a timing light on it to verify the spark is happening at the correct time (once you get it started). I have run into similar before and the only real clue I got was when the CDI finally died. Hope this helps. Cam.

Hillclimb#42:
New Crank seals? Bike smokes a bunch and doesn't smell like a day at the races? Its a gamble when you don't go through the bottom, too.

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