Cylinder Pinging

I've got an '03 PW50, about 6 months old, and about 50 hours riding time on
it. About 3-4 weeks ago, I noticed a "pinging" or rattling noise coming
from the cylinder. Thought maybe it was running too lean but it checked out
OK. Then I thought it was the fuel so I switched to a 93 octane...still
pinging. Compression checks at around 115-120 psi. I removed the head and
jug and decarburized the piston crown and head and checked for signs of
scoring....didn't find any. I'm out of ideas. Any suggestions greatly
appreciated.

 

I think what you've got is probably normal two-stroke
ring-dinga-dinga-ding cylinder resonance.

Many air cooled two-strokes had rubber bungs rammed between the fins to
counteract it.

 

.....don't look back.

 

No baffle, and the spark arrestor has been thoroughly cleaned.

That's interesting. I've suspected the stroke on the oil injector pump
needed to be adjusted down for some time now. I haven't done it because I'm
afraid I'll get it too lean and seize. These &*^!@ oil injectors are a bear
to adjust properly and even worse to try and measure. I didn't know about
the dieseling though...sounds like I might need to bite the bullet and do
it...or disconnect the pump and go premix...thanks for the suggestion.

Another good suggestion. I'll check that out too.