It now looks like a 79 SWM, but doesn’t really run like one.
The engine is back in the frame and running. The only problem was that whilst it was ok at tickover, there was a complete lack of power under load and it wouldn’t really rev out.
So, after think timing, disk valve, carb set-up, crankseals and all other nasty thoughts, 10 minutes in the shed with Gavin and hey-presto. Running it without the end-box on the exhaust and no problem. The exhaust back-box has never been cut, weighs a ton and is obviously blocked.
I used some petrol on it, followed by a blow-torch on a long pole to try to loosen the crud, but although better, its still not perfect. So time for surgery and cut it open and potentially remove some of the baffle plates. Did this on the Jumbo and its run fine since.
Cutting the rear box open revealed the problem, one of the baffle plates had come loose and was pushed back against the next plate, basically blocking the flow and any power from the engine.
Got Pete to weld the box together again (did a good job) and resprayed it with stove black. Job done. Put a new front brake cable together and installed the new plastics. Completed bike.