BN125 won't start from cold

Q. I have a Kawasaki BN125 that just does not want to start from cold at all. When it does fire up, the moment you take the choke off it stalls, and you have to be so, so gentle on the throttle until it’s warmed up, when it behaves itself.

It does seem to run pretty well when the engine has been warmed up however, such as after a five minute ride.

I want to sell it ASAP, it’s just I don’t want to sell it and have the buyer come back and say ‘you sold me a heap of crap’ if you get my drift, and I like to think I’m an honest man.
Anon

A. This sounds like a really weak mixture. The BN has a ‘coaster enrichener’ which is a plunger with a diaphragm that squirts fuel into the inlet from low revs. It’s on the left-hand side of the carb under a little cover held on with three screws.

If that’s seized up you’ll have the problems you’ve described. If that’s OK, check the fuel level in the float chamber.

The easiest way of doing that is to get a length of clear tube attached to the drain pipe on the float. Loosen the drain screw and make a U with that tube alongside the float bowl.

The fuel level should be no more than 2mm below the lower casting  edge of the carb body where the float bowl fits up into it.

If it’s lower the mixture will be weak and you need to adjust the float level. The pilot screw should set 1 and 5/8 turns out for pilot screw.