rpm's 1985 20hp

[Newyota]

Is 6000rpm sound about right at WOT?Have a tiny tach on it.

 

[boobie]

Sounds a little high.

 

[Newyota]

I was thinking it was also.When I put my tiny tach on it this summer I swore it was maybe around 5000rpm.Tonight I swear it read 5900-6000 on the river..Is the ignition module the only thing that may change this if it is bad.Do these ignition modules have a safety built in if the engine over revs and cuts the motor off or drops the rpms..Not sure what else would cause this?I just found info that maybe it should be 5500?

 

[flyingscott]

5500 is correct for a 20 hp.

 

[jimmbo]

The 20hp is rated at 5000 rpm, the WOT range is 4500 - 5500

The extra power/rpm you are currently seeing compared to the summer, might be due to the cooler denser air in the autumn compared to the hot humid summer air. Usually a person props their boat during the spring, then complains about rpm/power loss during the hot summer.

 

[Newyota]

Thanks..Never thought of that...Actually it was humid and low 80's yesterday. Water temp. 69.Would a strong river current affect rpm?

 

[racerone]

River current does NOT change engine RPM.-----Speed over the bottom of the river does change

 

[Newyota]

Thanks...I was just curious if a strong current or swirling in areas would maybe cause alittle ventilation or cavitation. I did not think it would cause a sustained rpm change.

 

[jimmbo]

Strong river currents will yield interesting GPS speeds. 40 mph going upstream, 70 mph downstream.