Rebuilt KX500 '86 but hard to start

Joined
Nov 13, 2003
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#1
I have a KX500 '86 that I have had rebored and a new piston kit put in. It started the first couple of times, now it won't start at all. Prior to rebuilding motor I always had trouble starting it, but eventually it would start, probably because i could kick it over faster due to less compression. The piston and rings and cylinder are still ok, the electrics have been checked and are ok too, carby and air filter are clean and reeds are fine also. There's no evidence of fuel mixture on the flywheel side crank seal or blowing white smoke ( when it was going). The flywheel woodruff key is ok and there's no movement and the timing is set at standard. Someone told me that the big end bearing could be worn in a spot where the piston reaches TDC and altering the timing. Could this be true? Any help would be much appreciated thank you.
 
Joined
Oct 28, 2003
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#2
sorry i cant help you too much, and correct me if i'm wrong:

If the timing was off do to your explained reason, it would only be off by a little.
If the timng is only off by a little bit, I think it would still start and run(maybe) but it would feel like crap because it wouldn't have the air/ fuel mixture fully compressed when ignited

In short, my point is that I don't think timing is the issue. But what do I know -- i'm only 16--don't worry i built the engine in my car and it runs peachy
Good Luck
 
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Nov 13, 2003
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#3
Yeah, that's what I thought. I push started it and it runs fine, I,II fabricate another kickstarter out of steel and make it longer ( cos' I broke the original one ) and try and kick it through it's full stroke. Get a couple more strokes of the piston to get it cranked.
 

kelsorat

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Nov 5, 2001
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#4
Double check your reeds, even a slight rounded edge or a fine crack will give you problems. When in doubt, change out reeds for new ones.
Also big bores require a starting drill most times.
I always had luck with the following procedure.
1.Hitch the bike in second gear.
2.Rock it back and forth a couple of times, you should feel the piston moving up or down as you do this.
2a. If you have trouble planting your feet firmly on the ground to do step 2, you could substitute with gently kicking through the kickstarter to achieve the same result. Kick 2 or 3 times, but gently.
3. Choke off, and kick that beast while lightly twisting throttle on the kick downstroke.

Worked for me