Yamaha 4 strokes not to idle?

[Redneck]

I know someone who has a 115 4s Yammy and he says he almost ruined this motor because he idles about 50% of the time. He fishes some rocky flats in N Fla gulf.

I thought the 4 strokes were tailor made for idling??

 

[JB]

Re: Yamaha 4 strokes not to idle?

If he almost ruined his engine it wasn't because he was idling 50% of the time. There must be other factors, including the possibility that some wrench, or wannabe wrench, had to sound knowledgable and didn't have anything sensible to say.

 

[Redneck]

Re: Yamaha 4 strokes not to idle?

JB are you saying it's Ok to run these 4 strokes on idle a lot? I have a 40hp Yammy 4 s and I fish the same waters and idle a lot too.

 

[JB]

Re: Yamaha 4 strokes not to idle?

If extensive idling harms an EFI 4 stroke there is something else wrong. I don't believe there is that sort of bug in Yamaha's firmware.

The final word on this should probably come from rodbolt.

I often ran my Suzi DF70 at idle for hours on end.

 

[1730V]

Re: Yamaha 4 strokes not to idle?

What does the manual say? What does Yamaha say? Call them.

 

[Redneck]

Re: Yamaha 4 strokes not to idle?

I got more info. The motor was not getting hot enuff. The pistons weren't expanding enuff, and allowing gas into the crankcase.
"Making oil". He was running less than a 1000 rpms a lot!

 

[JB]

Re: Yamaha 4 strokes not to idle?

Okay. Making oil makes sense. Rodbolt should have some advice on that score.

Also read the Engine FAQ on Making oil.

 

[rodbolt]

Re: Yamaha 4 strokes not to idle?

there is a tech bulliten out for some of the F115 motors. sometime in 01 or 02 I believe.
engine temp is critical, its mandatory to periodically check the T-stat.
after extended idle times you really need to spend at least 30 min above 4000 RPM and the engine MUST be capeable of 5800 or so at any given load.
unlike carburated engines fuel is injected reguardless of if it can be burned.
excessive combustion pressures due to engine lugging will cause blowby fuel to pass the rings.
periodic leakdown tests are needed as occasionally the ring gaps will line up. I have seen it twice. when they line up the main symptom is making oil.
other than that my F150 can spend hours idling