QuestionHi Mark,
Okay I bought a 1987 cr125 and rode it a few times, the second
time while riding, it bogged out and shut off. I was able to
restart it and kept riding. After I stopped to rest and went to
restart it I got nothing. I pulled the plug and it was black and
smelled of fuel. So I cleaned the plug and even changed it and
got nothing...starts to fire but won't completely start. If I roll it
down a hill and pop the clutch it seems to almost start but won't
stay running. Then I cleaned the carb and that didn't help. So
finally i pulled the cylinder off to look at the piston and ring and
the piston is black on top and charcoal like, the ring seems fine.
I am running the fuel:oil at 32:1. I was told by a friend to try
changing the main jet to a smaller size to make it run leaner, is
that correct? Any ideas are greatly appreciated!
AnswerHi Spencer,
Sounds as if the carburetor will need tuned to correct the air-fuel mixtures (jetting).
Jetting is not an easy task. It requires having a selection of jets available and time. It may require removing, changing jets, and installing the carb numerous times before the jetting is correct.
The spark plug must be kept clean between jet changes. You'll need to learn about reading the appearance of the plug to know what's happening during the combustion process and to know jetting changes to make.
I return tech information files by email. There was no email address with your question as requested and explained in my instructions.
Send me your email addy and I'll return several tech files to assist you.
Respectfully,
Mark Shively
