Saving Old Seagulls

Started the featherweight “special” today . Frickin loud with no exhaust! Will do a running video when the tachometer arrives in the post from China, but slow running and fast running works as it should.

You have embraced the dark side of the force Like the variable timing, which should get you some higher RPMs perhaps. For the exhaust a tuned expansion pipe would also help. Thats the limit of my tuning knowledge!

Walk on the dark side you do!

What stop the baseplate rotating from vibration & magnetic load?

Would be charmed to hear the sound.

I would have kept the mechanical function of the exhaust by removing the after half for most of le length, keeping the ends intact.

Sandro

Having no exhaust will actually be detrimental to performance. The exhaust creates back pressure as part of the two stroke cycle and that back pressure ensures the incoming fuel charge is delivered to the cylinder efficiently. Highly tuned engines have a certain length and shape of exhaust. Check out some of the two stroke cycle diagrams on line, which show this. A standard seagull exhaust will be better than no exhaust.

Heres a good example

It’s going to have an exhaust, just need to pull it off another motor and wanted to see if it ran in the meantime. At the moment Charles, my hand! The baseplate is fairly tight against the crankcase, and the handle is tight against the guide, so it moves much less than I expected, but once I put it through its places properly I will judge wether it needs a mechanism to hold it in place. The guide stops the baseplate turning more than 30 degrees either way of normal firing position, so worst that can happen if it does slip is engine cuts out, hopefully not detonation!

Got it running properly today, at WOT it's starving of fuel due to the new velocity stack but hand restriction on the intake got it up to revs.
https://www.youtube.com/watch?v=dZcQJeCysXI
Some improvement with adjustable timing top end (roughly 10 percent at WOT according to tachometer) and good slow running (I am aware it's not pumping water in the video at low rpm, I shut it off shortly after filming.)
Soon as fuel issue is sorted it should run sweet!