carb adjustment questions

[ryan04]

1972 125hp, I finally got the boat in the water last night after completely rebuilding the boat. I dumped it in the river and was standing in about knee high water and started it up. The engine was in the tilt position at this time and more than enough of the leg was under water to allow it to cool. I had attempted to adjust the carbs the night before on the muffs at home to stop the very seldom sneezing. Anyway, the engine started and idled better than I had ever heard it before...ever!! Then as I trimed down the idle dropped and the engine started to skip a bit then it sneezed a couple of times, and to add to matters my overheat siren came on. I turned it off within 2 seconds of hearing the siren. I have a new waterpump and impeller.

questions; why would it idle so perfect in tilt then when the engine is almost level it runs like junk? Could me playing around with the carbs have tuned it to lean so that's why it overheated?

 

[angus63]

Re: carb adjustment questions

Ryan
The exhaust pressure difference from trimmed up to full down can cause a load on the motor that will dip the rpms and richen up the mix. My 175hp idles at appx 800rpm trimmed up to the water intake and 600-650 rpm trimmed down. Do the adjustment with the motor in it's normal running position to eliminate the difference.
The overheat is probably unrelated to the idle issue. Maybe the intake was too high when trimmed causing the pump to stuggle pulling a head or the pump sucked some air? Next time start with the motor down and see what happens.
Also when the motor is trimmed up and running for a while, fuel tends to puddle up in the carb throats, whenb you trim down she gulps the extra fuel and may hiccup a bit.
Good luck

 

[tashasdaddy]

Re: carb adjustment questions

do all adjustment in running postion, tilted the carb floats are out of level, and may not close as they should.