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Low Rpms

bobbyr_12

New member
"I have a 17'whaler with 1

"I have a 17'whaler with 1994 88 hp Johnson Spl. I can only get 4600 rpms and 35.8mph out of it with a 13x17 stainless steel prop.It seems most other whalers with this motor ( or 90 hp) are running the 17 inch pitch or even 19 inch pitch and getting 5300 or 5400 rpms at wot.I so far have motor cavatation plate raised 1 1/2 inches above bottom of boat, confirmed that throttle plates in carb are opening completly, motor otherwise starts and runs great.Also checked compression it is 106,106,110,115. Could my timing be off, would it still run good if it was? I bought boat last Oct. just now finished painting and fixing it up, I didn't run it prior to buying it. Thanks for any suggestions on why I can't get more rpms."
 
Anybody have any thoughts on w

Anybody have any thoughts on why I can't get more rpm's . Timing off or something else? thanks for any impute.
 
"easy, start by having the mot

"easy, start by having the motor run on a MARINE dynomometer.Good dealers have such a unit.You need to determine the output of the engine before playing with props.Just because the sticker says 88 / 90 hp does not mean that it is putting out that HP."
 
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