My 1993 XT350 is running to lean. I can't find athe adjustment screw to fix it. A mechanic says Yamaha covers the screw with lead to prevent customer adjustment. Does anyone know where the srcew is?

Before you fiddle with the screw settings, check that the air filter is in good nick, that there are no air leaks around the carb manifolds and that the carbs/jets/needle passageways are all clean and clear, in case a blockage is decreasing the amount of fuel reaching the piston. Check also that you've got the correct grade of spark plug.

Mixture screw is set and left alone by the factory, as it shouldn't need adjustment during the life of the bike.

Paul

I just replaced the two boots from the motor to the carbs. They were severly cracked. I thought that was the problem. I'll clean out everything I can tonight and check that out. It ran great except for a clicking noise in the carb area last year. When the choke is on it doesn't make the noise. Once it is warm and the choke is off it barely runs. Thanks for your in put.

I just replaced the two boots from the motor to the carbs. They were severly cracked. I thought that was the problem. I'll clean out everything I can tonight and check that out. It ran great except for a clicking noise in the carb area last year. When the choke is on it doesn't make the noise. Once it is warm and the choke is off it barely runs. Thanks for your in put.

sounds like a blockage, do you use an inline petrol filter?

sounds like a blockage, do you use an inline petrol filter?

It doesn;t have a fuel filter. I'll get one of those and I'm in the process of taking the carbs off and giving them a good cleaning. Hopefully that will work.