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 Yamaha 70 bog at WFO throttle 
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Post Yamaha 70 bog at WFO throttle
It started doing it last hunting season, but I just lived with it. From a dead stop, I can hammer down and the entire hull damn near comes out the water like a hydra-stream. Runs flat out, no hesitation or bog what so ever. Will climb to 3/4 throttle and I just cruise there. Now from 3/4 to WFO is no change of speed, however it sounds like its bogging. Let off to 3/4, again no reduction in speed, but bog goes away. What am I missing? Not sure what to check on these 2 strokes. I would assume carb is clean being the throttle response from dead stop to 3/4. The only thing that I noticed during this time is the initial startup for the day takes a little bit to do. Pump the bulb a few times, and then it will start. It also takes a little bit to "clear its throat", then all good. I'm sure its a tuning thing, I'm just not use to messing with outboards.


Tue Sep 11, 2018 8:31 am
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Location: West Monroe, LA
Post Re: Yamaha 70 bog at WFO throttle
Main jet needs cleaning?

#CFFITR
#TheGhostBoat
#whoneedsphysicsihaveamudmotor


Tue Sep 11, 2018 9:57 am
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Post Re: Yamaha 70 bog at WFO throttle
have u tried running some fuel system cleaner in the fuel? like lucas or sea foam? have u looked at your plugs to see if they are fouling/gapped right?


Tue Sep 11, 2018 11:14 am
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Post Re: Yamaha 70 bog at WFO throttle
no I haven't checked the plugs, but it runs great till WFO. Could be the main jet Russ. I haven't taken the carbs off yet to check, but given the throttle response throughout the range (except WFO) made me believe that the carb "should" be clean. I do have some seafoam DA, couldn't hurt.


Tue Sep 11, 2018 12:01 pm
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Post Re: Yamaha 70 bog at WFO throttle
maybe the stator is crapping out on the top end? have somebody who knows what they are looking at check the timing, it may be off on the top end. just for kicks make sure the choke lever is hot hanging up and your butterflies are opening up fully.
it's probly just trash in a main jet.
I had trash in my idle circut on my airboat last week. ran the idle screw in and out a few times and the sucker cleared right up.

good luck and let us know what it was.


Tue Sep 11, 2018 8:47 pm
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