Please Help: Horizontal Cylinder Spark Plug/Gas Issue

[jimmygomk3]

The Bike: 2001 M750 w/ 23,000 miles (owned for 15k) ridden casually on weekends and in nice weather.

Applicable Updates/Services: Jet kit & termi low pipes (10k miles ago), last major service with valve adjustment (5000 miles ago), Ca Cycleworks ExactFit High Voltage Ignition Coils Kit (200 miles ago), Ca Cycleworks ExactFit Timing Belts (200 miles ago).

The Issue:  Recently (last two rides) after taking the bike out for < an hour ride, parked it overnight, then when I try to start her the next day she will turn over and start but run very rough with one cylinder obviously not producing much power.  After checking spark plugs, I found the horizontal cylinder plug was coated in soot and smelled of gas.  The vertical cylinder was fine.  I removed the horizontal plug, cleaned it off with a wire brush and some brake cleaner, reinserted plug and she fired right back up only to have the issue reappear the next day after I rode her and left her overnight.

I know that I am running a bit rich but my concern is more towards the gas on the plug.

Any thoughts would be greatly appreciated.

Thanks!
Jeff

[ducpainter]

Check to see if the vacuum line connected to the horizontal manifold has gas in it.

I think thew vacuum petcock connects there and could cause trouble if the petcock fails.

Another check would be to verify the slide on that cylinder is lifting properly.

If it's slow, or doesn't lift it will soot plugs very quickly.

[jimmygomk3]

ducpainter, thank you for your response.  I understand checking the vacuum line for the horiz manifold but how do i verify that the slide on the cylinder is lifting properly?

thanks for your help!

[ducpainter]

You'd need to lift and prop the tank, remove the air box lid and filter and run the bike. Looks down the carb mouths. When you whack open the throttle there will be a slight delay before they lift, but they should lift together and roughly to the same height.

Typically if the slide doesn't lift properly there will be a hesitation associated, but not always.

The cause could be either a bad diaphragm, a kinked vent hose, or it could indicate a vacuum problem with that cylinder.

If you don't find anything I'd look back to the coils as they're the last thing you changed.

I'd switch the two and see if the problem moves to the vertical.

[jimmygomk3]

thank you!!