Fouling spark plug

[beemerboy]

My spyder had 750 miles and fouled out the rear spark plug, (gas) I put a new plug in, took it to dealer. They found no fault. Bad plug we thought, run good about 150 miles and started running poor again. strong gas smell when sitting still and lots and lots of fuel vapor fumes coming from exhaust when shut down. (like when fueling care in high heat/sun) the rear throttle body and cover of air box is nasty with a gassy wet residue and even has back fired flames from rear throttle body. Dealer is young, any insight?

[jeffquadski]

I would have them do a compression and leakdown tests. It's possible that you have a cam timing issue.

[beemerboy]

I would agree, but its a random condition. valves would be on time or off, its more of a electronic ignition/fuel control issue.

[NancysToy]

The dealer's technician should be able to get support directly from BRP. They should be able to at least talk him through it further. Have the dealer lean on them.
-Scotty

[PE2817]

I am not sure if you are reving a cold engine. My Buells would foul a plug a in heart beat if you rev the engine while cold. I have not done this to mine as I have gotten use to letting my bikes idle till warm before riding.

[NancysToy]

My first thought would be to a bad plug wire or connection. The most common cause of single cylinder fouling is a weak plug wire, especially with resistor wires. Test the resistance of the plug wires, and connections, or just have the dealer start by replacing the offending spark plug wire and insulating sleeve. If that doesn't work, one side of the coil could be weak, and they can try replacing it.
-Scotty