Re: B/S lawnmover engine
Well, you're probably right about the gearing, but I wouldn't concern myself too much. The B&S engines tend to run about 3500 RPM max, and if you're using a used engine from a lawnmower, it may be even less.<br /><br />You're obviously not going to get a high-performance outboard out of this transplant operation in the first place. That is, unless you're talking about grafting one of the larger vertical shaft engines.<br /><br />For the typical 3.5-5hp B&S lawnmower engines, maximum performance is probably not going to be your main concern, frankly. If you can manage the installation at all, you'll have a hodge-podge outboard. Use a small hp outboard as your lower end and it'll be propped OK for your experiment.<br /><br />The biggest problem will be coming up with a coupling for the driveshaft to the engine. You'll have to install the engine on a raised platform, I expect, then put together some sort of coupler to connect the B&S crankshaft to the driveshaft from the outboard. You'll also need to hold the driveshaft in position vertically, I'd think. Some sort of mount that uses short coil springs, perhaps, to provide a bit of downward force.<br /><br />Then, there's the outboard's cooling system to deal with, plus any shifing mechanism that exists in it. You will probably be using an above water exhaust, so you can do whatever you want with the water cooling. Remove the impeller, or come up with some cool outlet for the water flow...maybe a nice fan-shaped spray out the back....the point is for this to be cool-looking on the water, right?<br /><br />I have actually seen a couple of these hybrids running. I suspect you could design a neat-enough looking thing that wouldn't embarrass you too much at the ramp.<br /><br />Or...you could buy a running Sea King for about $50 and get on with fishing.
