1979 KX250 hard to start

3 replies to this topic
  • fujioko

Posted June 06, 2008 - 04:12 AM


Hi ‘ya folks,

I recently picked up a ’79 KX250. After riding the bike, I decided it was not practical for my trail riding (way to fast). The bike is currently on ebay.

Anyway the bike is a real pain to start. I put in a new NGK plug and it still is a pain. I ended up using my huge power drill with a 13MM socket and spinning the engine over to get it to start reliably.

The bike will actually start better using a spark plug from my ’50 ford tractor. I speculate the shorter plug decreases the compression enough to allow the CDI to fire (assuming the CDI is failing). Does this sound correct?

Also, anyone know the correct gap for the NGK?


  • Fatback

Posted June 06, 2008 - 08:23 AM


id do a compression check first. thats an old bike, and who knows what the top end is like.

a bad top end will be very hard to start, as you said was your problem.

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  • shrubitup

Posted June 06, 2008 - 03:12 PM


dump a tsp of pre mix into the cylinder with the stock plug. this will give better ring seal and increase compression to make it start easier. this is the poor mans top end rebuild trick.

  • Jeekinz

Posted June 06, 2008 - 03:37 PM



If you were closer I'd buy that in a heartbeat.

Is it hard to start after it has been run already?

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