please help

[huntingtheworld]

i have a 1972 johnson electric start 25 hp that i think it wont turn high rpm's.the carb was cleaned 2 times and it is getting enough spark.it has a air screw i think thats what it is on the top if carb but i messed with it and no better.i have had smaller boatmoters and they turm more rps's thin this motor.any advice will help thanks

 

[oldcatamount]

Re: please help

when you say "air screw", are you talking about the low speed needle valve? That should be lightly closed and backed out about one full turn (approximately). You might look at some ignition parts, like points, plugs, and condensers. You need beter than "ok" spark for a motor to run good at full speed.

 

[tashasdaddy]

Re: please help

did you remove and clean the high speed jet? used a rebuild kit.

good reading here: http://forums.iboats.com/showthread.php?t=299680

 

[F_R]

Re: please help

Exactly what do you mean by low rpms? Half speed or less? If that is the problem, get your eyes off the carburetor and on the ignition system. OR compression. OR water getting into a cylinder. OR a ruptured fuel pump diaphragm flooding the cylinder it is mounted on.