Mariner 90 2 stroke smoking and rough at lower revs

[Chris]

A friend has a circa '96 engine on the back of a Humber...

When at idle it smokes quite heavily and sounds very lumpy at low revs (even for a 2 stroke)

Am going to try new plugs first and see if this helps, however any other tips...?

[jezza2011]

check the carb settings.
mine smokes a lot after ideling for some time.
you can also check the oil is ok. try to use good oil tcw3 ( quicksilver ah-hem lol )
any vids or pics to show it.
there is also an adjustment on the carb to oil pump but be very very careful if your changing that

[colcreate]

Is he premixing fuel/oil or using oil injection?
If its running lumpy and compression is good/equal on all cylinders then carbs are probably out of balance. Would recommend stripping them down and cleaning them, examining for spindle and float valve wear and a general tidy up. Check linkages are good and adjust/balance according to manual. Did this on mine and it is much improved, plus piece of mind that all is well and unlikely to seize due to a gummed up carb.

[uncle al]

does it just run lummpy on tickover when trimmed in as far as it will tuck under? If so trim it in so that it is straight up and down is it still lummpy?If so how old is the fuel?take out the sparkplugs and DONT wipe them are they all the same colour? if one is a differant colourput it into one of the other cylinders has the colour changed?If it has check idle air screw (mixture screw) it should be one and a half turns out from lightly seated on all three carbs,the book said a differant setting