Hard to tell from the description, but advice would be to check the fuel flow.
If you have an inline filter check that it's clean/replace.
Check the breather lines for the fuel tank (check valve in cap breather) and carb lines.
I'd then establish a baseline for your jetting regardless of what the previous owner says. I'd pull the carb, check the float height, blow out the passages and jets, and record what you have as a baseline.
Inspect the plug, check the model and gap and consider replacing.
Oil ratio at 50:1 is OK if using a high quality synthetic and not sitting wide open all day long. Oil ratio and brand is a topic in itself, and more oil definitely won't harm anything, but 50:1 isn't silly lean and many run around that ratio with no ill effects.
You could have powervalve issues, your silencer could need a clean and repack, you could be loading up and fouling the plug at low rpm, or could be running lean and starving.. you'll need to start ruling things out to determine what's what.
|