Thanks for posting the picture, Mark. I wanted to ask for one but didn't think it would be a reasonable request when it wasn't relevant to the case.
The principle of operation is very similar to the normal 4 stroke decompressor which momentarily bumps the exhaust valve open about halfway through the compression stroke. Of course the 4 stroke ones disable themselves when the engine is running more than about 1,000 rpm, while that Suzuki one operates all the time - but is so tiny that its effect at high engine speeds would be negligible. Briggs has its Easy Spin feature on the side valve engines, which holds the inlet valve open by a few thousandths of an inch during the compression stroke. They say their experimental work showed that it had a negligible effect when the engine was running.
