Plug check

When you are checking for lean/rich conditions after rejetting do you have to use a brand new plug ? Do you just warm up the bike, go around the block, then turn it off. Any help is appreciated.


I start with a new plug. Drive around until the engine is warmed up. Then I start a run far enough from my garage to run about 1/2 throttle for a minute (in a lower gear to match the local street speed limit) pull the clutch, kill the engine and glide to the driveway. Let it cool and check the plug for a nice warm brown color. You probably know that white is lean and black is rich (normally).

An older plug can also be a great indicator of engine ignition conditions. The condition of the electrode (the little thingy attached to the plug bottom) is helpful for longer term conditions like preignition, too hot/cool plug type, etc.

There are threads with pictures of plugs to help define what these are as well.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now