As already mentioned black smoke means a rich mixture, too much fuel or not enough air, nothing to do with the sump oil (unless you have tipped the motor the wrong way and blocked up the air filter with oil).
Hi MowingManiac, thanks for your reply.
Defintely didn't tip the wrong way - learnt that many years back the hard way. Airfilter checked this morning - no issues with it at all.
Is the choke opening completely when off?
I'm unsure of this offhand - no issues starting it first pull as has always been the case. I could check but I assume this'd need the carb removed from the plastic body - which is a bit of a PITA, seems all the rods etc are moving properly, carb is a tad grubby on the outside but as I'm very careful to always use stabilised fuel, shitty carb cleaner in the fuel (better stuff onroute thanks to Tyler's tip) and turn off fuel tap prior to turning engine off - I'd think it should be pretty spotless inside.
Someone may have used some wire to clean out the main jet, or the two holes in the bolt which holds the float bowl onto the carb, and enlarged the bores. The fuel inlet needle attached to the float might not be seating properly.
As I've had it nearly from new and certainly never done this I'd think it can be ruled out - but if you feel the carb needs to be pulled apart and checked let me know. Sounds like I'd only have to remove the fuel bowl to do this?
Just some thoughts, I have found those motors tend to be not too fussy with the fine details.
Thats been my experience as well - it'd worked very well for years and then this just started occurring. Part of my reason for thinking it might be the oil blend was that was one of the only variables that changed around the time it started occurring - but again the oils put in were all good quality and essentially when totalled about the weight Honda states 10W-30.
Is a puzzler.
