Fouling plugs... 96 EX500...

[VinceF2]

Hello all...

I've been working with my wifes EX500 when I can to try and figure out why I keep loosing the #1 cylinder... The old plug smelled badly of gas... and had black carbon deposits on it... I threw in new plugs and still no #1 cylinder... I pulled the plug and it was soaked in fuel... the gap was basically shut with fuel...

tested the coils and compression... all seems good there...

So... I'm heading into the carbs... but ummm what am I looking for? what causes this?

Any help would be greatly appreciated... I had the bike tuned by New England Motorsports last year and it ran fine when I parked it...

Thanks in advance y'all....

Mike

[Degsy]

Float stuck? Clean the carbs of all the varnish that has gathered over the winter.

Derek

[Honclfibr]

I believe if your bowl floats are set incorrectly (or if they've filleed up with gas and don't float right) you'll get a constant stream of gas from the tank, which will eventually overflow the bowls and pour into your cylinder, flooding the engine. Not sure about that though, anyone care to confirm or refute?

Also if your jet needle was stuck open I suppose you'd flood the cylinder at low rpms...but I can't think of what would cause a jet needle to stick open, does this ever happen?

In general though, once you've got the carbs off, I'd suggest completely disassembling them and soaking all the metal parts in carb cleaner. This is what I did on my EX, and after doing so the bike ran much better than before. The whole procedure would take you about 30 minutes to an hour once you have the carbs off.

[VinceF2]

Ok thanks guys... I was kinda thinking something must be stuck... and I did notice that the cylinder would kick in sometimes at higher rpm....

I guess putting stabil in the tank and running it before parking it isn't enough... maybe I didn't run it long enough....

Thanks for the replies gentleman...

Mike

[stoinkythepig]

Before you go to the trouble of taking the carbs apart, you should ensure that you have a "good" spark. Assuming the spark is present and bright blue, you can move on to the carbs. Otherwise, check the resistance of the spark plug wire from the coil to the plug. Should be 4.7k ohms if memory serves. Also, check the ignition pickup coils for equal resistance (can't recall what it should be). If one is open that would be the problem.

I suspect the problem is carbs but it sounds like you did not thoroughly check the ignition system and it's a whole lot easier to do than screwing around with carbs.

[VinceF2]

Hey Stoinky....

I should have clarified that I did test the coils resitance... and used a spark tester... the spark is strong... as strong as my EX race bike that I compared it against... I also compared the resistance to the coils I have on my race bike... and spares I have lying around...

I'm pretty sure the ignition system is ok.... but I thank you for the post... I was hoping I wouldn't have to pull the carbs... not that it's hard... just annoying...

Thanks again,
Mike

[stoinkythepig]

I'm in agreement with Honclfibr then. You likely have a stuck float valve or a needle that's popped out of it's jet and can't go back in. Pull the carb top first since I think it's accessible without pulling the carbs off.