Carb adjustment NEW T9.9 high thrust?

gss036

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Jan 18, 2003
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My new T9.9 is running rich and leaving a black exhaust streak down the rear of the motor. I can't find an adjustment screw to lean it out, just a screw to set the idle higher,etc. I stopped by the Yamaha dealer and guy at the counter said that I can not do it, that thing is sealed.
Anybody know the secret to leaning this thing out?
 

gss036

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Re: Carb adjustment NEW T9.9 high thrust?

Bump^^^^ Any body know how to do this?
 

rodbolt

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Sep 1, 2003
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Re: Carb adjustment NEW T9.9 high thrust?

yes, take it to the dealer, they will have to drill out the plug covering the mixture screw and carefully check that the enricment valve is functioning properly.
and trust nothing most counterguys/salesman say :).
look for a school certification from yamaha covering fuel systems,4 stroke, advanced 4 stroke and master tech.
if the dealer employs a tech with the above certs it will be on the wall, simply ask to see it.
 

gss036

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Re: Carb adjustment NEW T9.9 high thrust?

Thanks for the reply Rodbodt. It is a new engine and only has 50-60 hours at most.
The guy at the counter is an OMC mechanic (semi-retired), so he does know some things about a Yamaha, but is not hired as a mechanic, so does not want to engage too many questions like this, but did only because I have know him for a lot of years.
 

rodbolt

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Sep 1, 2003
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20,066
Re: Carb adjustment NEW T9.9 high thrust?

OMC and Yamaha NEVER partnered with anything and its painfully obivous no matter how good a friend or trusted he is he doesnt know squat about YOUR yamaha.
just the way life works I guess.
kinda like if you asked me a question about heart surgery.
I work on pumps all the time, centrifical,positive displacement,rotary,pulse diaphram.
doesnt mean I can disscuss the human blood pump.
 
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