Hi everybody. I own a Kawasaki EX500 1989 with 17500 miles on it. Recently I have a big problem with it. From time to time rpm's will drop to around 1K and bike won't response to throttle or even engine will stop if I apply gas. One day one cylinder wasn't working at all. But the day before it was running great. Oil was changed, spark plugs are new, carbs cleaned. It seems that the problem arises when the bike is very well warmed up. May be anyone has an idea what could be wrong (other than the bike is too old). Any response will be very appreciated.
Thank you

Hmmm... Weird... Of course then again, my GS500 has been acting all ghey lately, too...

PM me, and I might be able to hook you up with some helpful pointers. :)

Sounds like you migh have a bad spark plug or a bad connection. I would check the plugs first.

Kaws are known to have bad carbs (mine included). Upon close inspection I found an actual whole in my carb that was letting way too much gas flow to the cylinder basically drowning it out preventing any spark. Here is a list of things I would check:

alternator and coils
carbs checked up
correct gapped spark plugs
take out a spark plug one at a time and turn over the engine to see if compression is still good
electrical connections (if the bike is old the connections get rusty and need to be sanded)

tell me if you do some of these and it comes up negative.

Could be an ignition coil.

test

Victor did you ever figure out what was wrong? I'm gonna buy one of these soon and it might be nice to know.

Not really. I was stupid enough to leave my bike outside for a winter. My battery died, carbs probobly clogged, etc. Few days ago I finally make it start and know I'll adjust carbs and I'll see what will happen.