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9/7/2021
Yachtwork, Marine Engineer
Category: Boat
Satisfied Customers: 3,993
Experience: MEC3 and RYA Yachtmaster Ocean
VerifiedHello- It's great that you are getting some time on the water. I am sorry about your slow turning engine.
Your BF40 should be up around 5,500 to 6k at wide-open throttle. that is a big difference between 2500. There are a few things to consider. One is that the engine can't produce much hp at 2500 so we could triple our output or more at higher rpm's.
Let just say that the outboard is running right, then the problem is most likely we have the wrong prop or a bent prop. Take a good look at the prop and make sure it's in good order. If so then look on the side. There will be a number like 12x13 or something like that. That is diameter and pitch. I would guess on a pontoon boat your pitch should be down around 9 or so.
Let me know what you find.
Scott
More rpm's provides more hp thus more speed. 16mph is not bad, but it's not good for the engine to run at low rpms like that. It overheats the exhaust valves. At our shop, we would put a digital tach gauge on the motor to test if the tach was reading correctly. At 16mph we are looking more like an 11" pitch. Check what your current pitch is.
Scott
Yachtwork, Marine Engineer
Category: Boat
Satisfied Customers: 3,993
Experience: MEC3 and RYA Yachtmaster Ocean
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