honda bf100, runs good, but....

[dkonrai]

weather today was high 90's. took the boat out to fine tune the motor.
started fine, couldnt get it to really slow idle, but i guess that is asking too much for a 10 hp to idle down like a 3hp?
since fishing was slow, i decided to test the motor. when i put the cowl back on, at wot, after 10 minutes, it shuddered, then shut off.
took off the cowl and the motor was hot. ran the motor for at least 2 hours, with the cowl off and it ran fine. put the cowl back on on........ and the same thing about ten minutes and it shut down.
do i need a hood scoop???
here is the you tube link
http://www.youtube.com/watch?v=7tsnO6F0JZc
http://www.youtube.com/watch?v=0saccQU5GtE
this is how my 3hp idles
http://www.youtube.com/watch?v=LMMLgN0wTO0

 

[zzzzz]

Re: honda bf100, runs good, but....

you probably have an exhaust leak somewhere under the cowl that lets fumes build up and the motor dies from lack of air

 

[dkonrai]

Re: honda bf100, runs good, but....

how do i check for an exhaust leak. the motor sounds good? no hissing or misses.
dk

 

[zzzzz]

Re: honda bf100, runs good, but....

look for traces of soot around the base of the block...with it running listen around the block base with some kind of stethescope

 

[hondon]

Re: honda bf100, runs good, but....

This is a very common problem.At the rear of the engine look down into the depths of that lowwer cowl and you will see a horn looking thing snaking down into a seam where that cowl or oilpan,however you want to refer to it ,meets the midsection.That horn develops leaks and spews exhaust into the engine cavity causing oxygen starvation.No quick fix .The cylinder head or powerhead have to come off and the exhaust horn replaced.