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cobb

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AT FULL SPEED I'M DOING AP

AT FULL SPEED I'M DOING APPROX 40MPH AT 5000RPM WITH 15' PROP...SMALL 16FT RUNABOUT BOAT....DOES ALL SOUND ON PAR???
 
"Cobus, sounds like you are ve

"Cobus, sounds like you are very close to max speed (a little tweaking could maybe get you about 2 more mph - on flat water/calm day of course).

You should be shooting for a wide open throttle (WOT) of between 5000-5600, with your ideal rpm around 5400 (that's where you develop your max horsepower).

But your set-up appears to be fine..."
 
"thanx graham, i forgot to say

"thanx graham, i forgot to say that i'm about 2000ft above sea level, im sure i'll get that xtra miles and rpm at the coast, or am i mistaken?"
 
"You are absolutely right. You

"You are absolutely right. You are not "way" up there, but yes, the motor would "breathe" alot easier at sea level.

So sounds like you are set-up at probably as close to the optimum that you can get..."
 
"thanx for the input...ps, do

"thanx for the input...ps, do u have any knowledge of a 140 johnson v4 1980??..i need some help on it"
 
"Put up your questions - if I

"Put up your questions - if I can't help, someone surely can - there are alot of knowledgable people on this board..."
 
"ok, the long and short is thi

"ok, the long and short is this.. engine starts up ok, idles great, water flow good(peehole), warms up nicely etc etc..revs up great with fast idle lever, put in gear, bogsdown (feels like only 2 or 3 cyl running) actual fact, need to rev up to 4000 rpm, drop lever and slam into gear..then oxwagens away and planes only just...the confusing part is, when idling and going into reverse, no problem, revs stay up etc....does this make sence...ps. compression test was done all ok, did a decarb, lync and sync set to best of my knowledge, wot also tested, plugs new (champion not ngk) any ideas would be appreciated"
 
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