Hi N1KK0,
Dark black smoke is over fueling , if the flyscreen/mesh in the snorkel end is a non factory fitted item you may
have restricted air flow giving the mower a richer mixture.
Run the mower until hot then adjust the fuel mixture , first remove the mesh if it's not standard.
Cheers
Max.
Sorry I just managed to get around to being in a position to TRY and find this issue. First had house guests, then needed to repair where the handlebars had broken at that point just where they screw onto the bottom section - I might again be in the running for the ugliest weld competition!
So I started by removing ~half the oil and replacing it with fresh stuff - I figured this would negate the additive's addition being an issue
Next step was as per NormK's suggestion removing both airfilters (and I will note that the snorkel is a stock Honda snorkel, I have the OEM style air filter with it's foam prefilter on and the top section (which generally was made to have a Victa style filter in it, only has a cylinder of domestic fly screen in it - the though being just to remove the biggest crap but as the carb was NOT tuned for two filters I didn't want to affect this much - the fly screen would have no impact on airflow).
So ran with both filters off - and any smoke was very negligible - was the middle of the day so harder to see but this definitely assisted.
So then as per maxwestern's suggestion I tried the fuel mix adjustment - I have a cheap hours meter/tachometer but found that following this process from the diagram was hard to get achieved correctly.
Allowed engine to warm, then screwed the screw completely in - which even with the throttle set to idle gives a very high RPM (I was getting 3300-3400rpm) - you then screw it out and the RPM decreases, but the instructions say to set it to the point where at idle throttle the RPM are highest? And this was when it was screwed nearly completely in - but at this level it was maxing the engine out and throttle changes did nothing, other than when I moved to the off position.
So something seems awry here - I had to remove the throttle cable for the handlebar repair but am pretty sure it's spring loaded section up the top was replaced correctly so I don't think it's the throttle giving the issues as when I check it down on the governor section this all appears to be pulling back the correct amount.
So not sure how to follow this diagram when it gives a massively odd result - the previous setting of this fuel mix screw seems to have been very different as I had to screw it in a LONG way.
So this seems to have made more of a mess. :-/
