Motorcycle Repair: Yamaha TW200 running too rich, prescott az area, indio ca

Question
My TW200 appears to be running too rich, the spark plug becomes black in very little time.It is a 1989 that I bought in Indio CA. I now live in the Prescott AZ area.  Can it be I need to rejet the carb? If so can you suggest what number jet to purchase?

Thank You

Answer
Not sure how the bike is running.  If the plug is just becoming black and not fouling but you are able to ride I would leave it alone.

Also, what type of riding are you doing? The easiest way to tell how your bike is running is to warm the bike up, then replace the spark plug, start it back up and quickly put it in first and ride it at 3/4 throttle for a couple of seconds - pull in the clutch and hit the kill switch quick!! Now pull the plug - if it looks nice and brown, it's just your riding style, maybe its slower or more trailriding, if it's black then you need to look further.

If its jetting follow these guidelines, but mind you, on an older bike it can be many things - clogged jets, dirty carbs, worn piston/rings, worn cylinder, reed valves, etc..

Basic Jetting:  http://www.mudbog.net/basic-carburetor-jetting.html

Good Luck!

Anthony
'Ride Today - Live Again'