Hello Gents,

Alas this is a bit of a long running saga - continued from here (https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/118994/1.html) but as that was 2yrs+ ago I thought I'd start a new thread.

In the past, it wasn't running great but it was usable - but last time it was blowing so much dark smoke I found myself feeling sick after 15mins usage & had to stop. Tried to tinker with carb settings but to no avail. Hence here I am hoping for guidance.

I will try to describe issue & whats been done/tried to assist those who assist me:

ISSUE:
Engine blows noticeable dark smoke when revving up (ie you hit a thick patch of grass, the revs slow, then when it gets back to standard RPM it'll puff smoke).

SETUP OF MOWER
Currently has quality full synth 10W-40 oil in it (freshly changed in to see if would help, nope!). Has a sparkplug thats one step 'hotter' than standard one (as recommended on here). Regularly has Redline S-10 fuel cleaner put through. Air filter clean. Everything else is standard, does have a Masport factor snorkel specifically for the GXV160 - BUT I do not run the extra high mounted filter in it - I only have the standard low fitted Honda filter, the high intake of the filter's intake has very coarse fly screen in it, but nothing else - so air flow would not be restricted vs a single low filter. Fuel tap is always used so fuel not left in the carb, fuel stabiliser is always used in all fuel.

THINGS TRIED
Multiple changes of oil to higher viscosity, hotter sparkplug, new airfilter, trying to adjust the two screws on the carb (though I was kind of adjusting, viewing results and then adjusting to get no smoke - but could not change correctly). Tried to adjust the governor (followed Youtube tut but not sure if it was done right).

QUESTIONS
1) Could the valve clearances be the issue? I have had the mower 7yrs or so now, lots of use and I have never adjusted or checked them - I have asked here if I should do or if it is hassle for no good reason, never got any replies.

2) I suspect whatever the issue is - I've further stuffed things up by changing other settings TRYING to fix. i.e the carb is probably incorrectly adjusted, the governor is likely incorrectly adjusted etc. Is there an order I should try and use to get each of these bits correct as they all seem to affect each other so I'm unsure which one to do first?

I will note this - the carb fitted (which I am certain is the OEM carb, has two screws to adjust it. A larger plastic one towards the top of it (not sure the proper setting for that one or what it's for) & a smaller metal one thats on the front, lower down on the carb. VERY ODDLY this screw is only adjustable ~1/4 of a turn either way, as the plastic cover under the air filter box seems deliberately placed to block this being altered any more.

In contrast the replacement GXV160 carb I bought has that screw (which I think is called the pilot screw) being fully adjustable.

Thanks in advance - sorry for the long winded info but didnt want to miss things that might be needed.

Nick