Motorcycle Repair: spark plug fouling, mixture settings, yahmaha

Question
Chris,  I have a 1989 Yahmaha FZR600,  and I am have a problem with the spark pluigs fouling all the time.  What can I do ?.

Sincerely , Cliff Ross

Answer
Hi Cliff.
 Here are a few things to check on the bike.

1)  Have the main jets been changed from factory or have the mixture settings been changed any prior to this problem coming up?

2)  Is the air filter due for replacement?  Yamaha's are notorious for running rich when the air filter is clogged.

3)  Is there anywher that there is arcing from the plug wires to the engine or frame?  This will rob power from the plugs and cause the engine to appear to be running rich.

Start with thosae and let me know what you find.
Good luck.
FALCON