Yamaha F80 'sneeze' at idle problem

[Buck Snort]

Hello,
I purchased the F80 new in 2001 and believe the 'sneeze' problem has always happened. It will not happen more often than once every 30 seconds and some times not at all. I sync the carbs every year using mercury filled tubes and noticed the sneeze doesn't always happen on the same cylinder.

When I start the motor for the first time in the spring or after it has sat for a few weeks without being used, initally the motor doesn't seem to fire on all 4 cylinders. You can hear one or two cylinders sporattically firing with the other cylinders for about 20-30 seconds until all 4 are firing and it responds normally to throttle increases.

The motor runs like a top otherwise.

Any and all thoughts are welcome.

Thanks,
Jeff

 

[cousinabe]

Re: Yamaha F80 'sneeze' at idle problem

only two things on that motor will cause a carb spit back, a lean air/fuel mix in the intake tract or a leaking intake valve.
as valve trian isues are incredibly rare and carb trash isnt I would say try the carbs.
it may be due for a carb cleaning. sounds like your low speed circuits could be clogged up.

also, have the link and sync checked by a shop with the tech mate tool or its equivalent.