Honda BF5

Lee1024

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Joined
Nov 12, 2018
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3
I have a Honda BF5 with the standard 7.5 inch prop. What I am finding is that it wont reach max revs with the throttle wide open. Does anyone have experience with this engine, and especially re-propping to the 6 3/4 inch alternative prop available for this engine.
 

ahicks

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Sep 16, 2013
Messages
3,957
That would be a step in the right direction. The question would be are you jumping out of the frying pan into the fire? Without knowing how many rpms you are turning now, and how many you want to turn, it's anyone's guess which prop might be closest to your target. The smaller prop could overshoot your target....
 

Lee1024

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Joined
Nov 12, 2018
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3
I cant quite remember what wot gives as revs, but it is well under the max engine revs.
How do other owners find this engine, as this is a stanard set up....what revs are you seeing at wot.
 

QBhoy

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Mar 10, 2016
Messages
8,286
Loads of variables in this one.
Generally these wee engines are very generally propped to put up with a range of general uses. They don’t often come with a rev counter either.
The main thing that determines the rpm on these things is what boat it’s attached to.
If it was on a 16ft old wooden displacement hulled slow fishing boat running at full throttle doing 5/6 mph it would obviously be pulling much less rpms than if it was on a small 2.5m inflatable tender doing planing speeds of 10-15mph.
Most folk don’t worry too much about it with these wee things unless it’s getting used way outside it’s design target boats.
 

QBhoy

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Mar 10, 2016
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8,286
It is on a small rib and i am struggling to get it to plane

Ah. That’s maybe the issue. What size is the rib ? I have a couple of small ribs. One is 2.7m and the other is 3m. The 3m planes easier than the 2.7m. Both will plane with one on board with an 8hp Yamaha 2 stroke. But only the 3m will plane with 2 people.
Your wee engine being a 4 stroke might struggle for grunt to get it on the plane. If you go lower pitch, on the off chance it manages to plane, it will run out off puff if you do get there.
Basically the engine is being asked a lot of and you need bigger if you want any sort of decent results
 
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