40 hp 2 stroke yamaha neutral runs perfect in gear bogs

[Jamiesonb]

In neutral revs fine when I put in gear only does about 5 mph
Last 3/4 of throttle makes no Change butterflies open all the way
Fuel filter clean, vent open, new fuel connections
Any chance weak coil

 

[99yam40]

Re: 40 hp 2 stroke yamaha neutral runs perfect in gear bogs

Not likely.

Check compression on all cylinders, test spark with spark tester to make sure it has strong spark, test timing with a inductive timing light to make sure it is advancing properly.
If all of that is good then pull and clean carbs

 

[JB]

Re: 40 hp 2 stroke yamaha neutral runs perfect in gear bogs

Howdy, Jamie.

Welcome to iboats.

Join the club of people fooled by outboards that PRETEND to run fine as long as there is no load on them, then fall flat when asked to do a little work.

Your outboard is probably running on one cylinder. Try pulling (carefully) each plug wire, in turn, while at idle. The one that doesn't kill the engine is on a dead cylinder.

Troubleshoot the dead cylinder as though it were a single cylinder engine that won't run; spark, fuel, compression, scavenging,, etc.

Good luck, and let us know what you find.

 

[jeffersondodson561]

Re: 40 hp 2 stroke yamaha neutral runs perfect in gear bogs

Your prop could be spun as well.