My bike is still having issues with the rear plug carbon fouling causing the engine to miss. Ive replaced the wires and intake gaskets. The idle mixture screw in the CV carb is at around 2 1/2 turns from closed. The bike starts fine although it will pop through the exhaust when I start it after its hot if it has sat for a few minutes. No popping through the carb. I am running a Crane Fireball Hi-4E ignition module in single fire mode with a Crane single fire coil. Spark looks good on both cylinders. I am not using the voes. With the voes connected, I get too much surging and bucking at low speeds. I found a ton of threads here in reference to the rear spark plugs fouling but, as usual, no one seems to do a follow up to know if any of the suggestions that they were given worked. Any thoughts?

 

the crane coil that is single fire the 2 round type unit - i have replaced lots of them they tend to crack and it causes a knock out of one cylinder - switch the trigger wires and plug wires to see if it moves to the front

 

if it were the coil, wouldn't I have a firing problem? Both cylinders fire perfectly. Nice crisp blue spark.

 

Have you checked the compression?

 

And running the VOES really shouldn't be making it surge and buck, there is some other problem going on there.

 

Definitely do the switch as john stated. At the least it will eliminate ignition issues. And Yea a comp test is in order for further diagnosing. Is 2 1/2 on the mixture a little too much? show a pic of your plugs.

 

OK. I'll borrow a compression gauge and do a test. I agree about the VOES but, I was advised to remove the vacuum from it and it did cure the surging at light throttle issue.

 

Any oil getting through the valve seals?

 

Thats a real possibility. Im using about a quart of oil every 600 miles. There is no smoke at startup or under hard acceleration though and Ive never seen anything "wet" on either spark plug. The bike did sit for a long time though. Ive ended up replacing juts about everything else made of rubber on it.

 

I dont know how far out is too much on the mixture screw. I juts lowered the idle on it and adjusted it to where it sounded the best to my ear. I can screw it in all the way and it will idle although the rpms do drop. I could probably get by with the screw out around 1 turn if needed.