i have cleaned the air flter....no difference....any clues.....Dave

Out of the exhaust pipe I'm assuming. Does it only make black smoke when you start the bike for ~30 seconds? Or any time you rev the engine? Or always?

hi..after standing for a while...it starts easily...ticks over revs without smoke,then it gradually starts to run rough and puff out the black smoke...it then struggles to keep going and finally stops....cheers...Dave.

As a general rule: white smoke from the exhaust is burnt oil and black smoke is too rich a fuel mixture.
There is more than likely an issue with the float height in the carb/s or the needle and seat.
Pull the dipstick and see if the oil has a petrol smell to it. If it is a too rich fuel mixture that is stopping the bike from running the cylinder walls will be getting washed with petrol which then goes into the oil.

Hope that helps.

Many thanks....i will check it out.....cheers...Dave.

Quote from: moe_tunes on August 31, 2023, 02:18:59 PMPull the dipstick and see if the oil has a petrol smell to it. If it is a too rich fuel mixture that is stopping the bike from running the cylinder walls will be getting washed with petrol which then goes into the oil.

And if you do smell gas in the oil. flush/change the oil.

You need the 'mint' engine I'm selling!