Gas Millage and Spark Plugs

[smitty74]

Ok, so I have a 1990 xv535, that I bought used a week ago. Here is the issue, it seems to run rich, and I am only getting about 70-100mi out of a tank of gas. I ran seafoam through it, and changed the spark plugs, and it accelerates smoother now. One thing I did noticed when I changed the plugs is there was oil on the threads, and the end of the plugs was charred black. I know that the black on the plugs is from the bike running rich, but not sure why there would be oil on the thread of the plugs. I need help with both issues. I am worried that there is a major problem, and that's why there is oil on the plugs. Also if there are any suggestions on why millage is so bad I would be greatfull. Thanks for the help!

[Johnj]

The question is how big is your tank? 3 gal. tank plus 35 mpg equals 105 mi. Then what kind of gas are you getting. If your using a blend your gas mileage suffers. Seafoam is a great product but you have to clean and adjust your carbs, including syncing them.

Spark plugs, every time I buy a used bike when I get it home and change out the plugs the old one look all sooty and dirty like. Just change them and when you service the bike in 3k you can read the plugs.

Oil, make sure you DO NOT use automotive oil with friction modifiers, use a motorcycle specific oil, or a diesel truck oil, like Shell Rotella.

Good luck

[smitty74]

My tank is 3gal. I am not mixing gas. I use 87 octane. I will look into getting, my carbs cleaned and synced.

[Johnj]

Your oil company might.

[pchast]

Have you cleaned or changed your air filter?