What should my max RPM be at?

[dthiessen]

I have an '89 Bayliner 17 foot with an 85 hp Force motor without original manual or motor info. Does anyone have any idea what the max RPM of this engine should be? I'd hate to over rev my motor and cook it before getting to enjoy it! If it helps I have a 13.5R 15 degree prop. on it.

 

[pnwboat]

Re: What should my max RPM be at?

5500 RPM is the maximum recommended manufacturer engine speed.

 

[jerryjerry05]

Re: What should my max RPM be at?

The 85 on a 19 ft. with a 15p
Probably not gonna work too well.
That boat/motor combo usually had a 17 or maybe a 19.
Take it for a spin and see what it does?

 

[BlueFishCrisis]

Re: What should my max RPM be at?

The Bayliner Capri came with an 85 HP model on the 17' versions, along with a 15 p prop. Are you sure it is a 18.5??

My 125 Force on a 18'11 Capri will turn over 5500 with a 15 P alum, up to 5500 with a 17 p alum, and just over 5500 with a 19p SS prop....

 

[dthiessen]

Re: What should my max RPM be at?

your right! I've just been going by what was given to me for boat info. Just measured the boat and it's a 17'.

 

[jerryjerry05]

Re: What should my max RPM be at?

Blue fish. The prop/rpm's readings don't seem right?
The 17p AL and the 19p SS is a difference of 4 pitches.You shouldn't get anywheres near the same readings with the difference of the 2 props??
A 17A and a 15SS would equal about the same.The 19S would be about the same as an 21A
Is your tach reading right??

 

[BlueFishCrisis]

Re: What should my max RPM be at?

Blue fish. The prop/rpm's readings don't seem right?
The 17p AL and the 19p SS is a difference of 4 pitches.You shouldn't get anywheres near the same readings with the difference of the 2 props??
A 17A and a 15SS would equal about the same.The 19S would be about the same as an 21A
Is your tach reading right??

I have always thought it was odd. The 17A is slow to get out of the hole, while the 19 does quite a bit better, and gives me a bit more top end speed. I don't have any reason to believe the tach is off..... the 15A and 17A are correctly proportionate, and the tone / sound of the motor corresponds to the RPM correctly. It doesn't bounce around or cut out or do anything erratic either....

 

[BlueFishCrisis]

Re: What should my max RPM be at?

your right! I've just been going by what was given to me for boat info. Just measured the boat and it's a 17'.

:encouragement: I always research my boats to make sure what the previous owner told me is accurate.