Saving Old Seagulls

Anyone out there tried to balance the crankshaft and flywheel of a seagull. It is done in motor cycles to remove the vibration.

Interesting

I've thought about the same.

Was thinking of modifying a flywheel with a series of steel plugs to adjust the balance

The problem I envisage is achieving a meaningful measuring system

Rex

With single cylinder engines you can not get perfect balance. You just move the vibration to a different rev range. The research I have done suggests that 65% balance is about the best that can be achieved. This is the difference between the power stroke and compression stroke. I am tiring to find out how to do the calculation. Static balancing seems to be the best way to go.

Andy I've played with the balance in some of my higher revving motors, they're never going to run smooth, with luck you can move it to a point where the boat doesn't resonate enough to loosen your fillings.
I always do the flywheel so that it's completely neutral, as the thought of one of those shaking itself to bits at 5000+ revs right by my ear makes me watertight below the belt.

So what you are saying Charles is that the flywheel is balanced on its own. The flywheels seem to be very out of balance so might be a good place to start.

Andy here's some pictures of the bar I use for flywheels, it fits all of them from the Marston to the Seagull Sport.

Sorry I take such a dreadfull pic all it is is a high tensile threaded bar with turned down ends with 2 threaded cones to centralise & hold the flywheel.

then there is the prop , both static and dynamic balance need to be attended too .