Yamaha F60 idle/high speed missing

[crochetl]

My F60 yammie has an intermittent problem, At times it will idle like a top fuel dragster and during high speed you can feel it cutting out and at other times it runs perfect. If i tilt fully it will run poorly next time it is started.Carbs cleaned several times, little or no trash found and nothing in fuel filter to indicate dirty fuel. Changed plugs,Gas,Tanks.Installed extra fuel filters. No gas running out of carbs to indicate flooding, Pumping primer bulb has no affect, Im starting to think its something else. Valve clearance in spec.

 

[andy6374]

Re: Yamaha F60 idle/high speed missing

When the intermittent problem arises test for spark.

 

[crochetl]

Re: Yamaha F60 idle/high speed missing

As in a possible arcing? thought about that but it hasnt given an oppurtunity to check in the dark yet.

 

[andy6374]

Re: Yamaha F60 idle/high speed missing

Sure, that's a possibility as well. But what I was more or less going on was no spark at all.

 

[crochetl]

Re: Yamaha F60 idle/high speed missing

Just ran it on the muffs in the dark but as i suspected it ran like a dream, I guess i will have to wait till it acts up again and start pulling plug wires to see if a cylinder isnt firing.

 

[rodbolt]

Re: Yamaha F60 idle/high speed missing

the fact that tilting the motor can trigger it I would suspect a fuel/carb issue. about the only way to catch an intermittant like this is to check coil primary and secondary voltages while its missing.<br /> best I recall that system uses one pulser coil as a trigger and each coil simultaneously fires two cylinders, <br /> sometimes if you pull one plug wire it will kill two cylinders cause the coil secondary circuit is not complete. thats why a KV tester and a peak reading capeable multimeter is nessasary for ign tests. but yours sounds like fuel.