1/2 power motor

[Russ Griffith]

I have an early 90s model 70 HP Yamaha that I have run for nearly 10 years it has always started good and run smooth. It still starts well and is not missing but its as if exactly half of the power is gone. I've cleaned filters, changed bulbs and fuel line connections and still have a 35 Hp motor any ideas?

 

[GrindKore]

Re: 1/2 power motor

I have an early 90s model 70 HP Yamaha that I have run for nearly 10 years it has always started good and run smooth. It still starts well and is not missing but its as if exactly half of the power is gone. I've cleaned filters, changed bulbs and fuel line connections and still have a 35 Hp motor any ideas?

Check your rectifier or voltage regulator. Although I have a different motor, I have had experienced similar simptoms to yours. Turned out the rectifier was bad, and upon replacement motor was able to reach rated WOT RPM.

 

[Dunaruna]

Re: 1/2 power motor

Coils and/or plug leads would be my first port of call with the MM. If they test o/k, take a look at the plug lead rubber boot, the end of the lead has a spring that clips into the core, that spring can work loose and or break and not contact properly.

 

[Mas]

Re: 1/2 power motor

What's the compression numbers?

MAS