thanks mate, yep, twin cylinder 2-stroke. Last time I wrestled with this bloody engine I got it running OK- the carby is very simple and has minimal adjustment- I cleaned out the choked up header and got a better seal between the carby and the block, all horribly difficult tasks involving working space- having removed and put back on the carby throttle linkage the idle and starting settings were bit off but it was finally starting and running OK. This time I went out and there was no spark. So the next day I got another Lucas SR impulse magneto out of my spares (Lucky!) and swapped it on. Nice bright spark, timing seemed about right (just after TDC). Trying to adjust the timing is a RPITA.
Along with 5 liters of fresh premium I took a near new fully charged bike battery out and spent the day hand cranking to get the flywheel going and then pressing the Dynastart button. I also liberally used about a 3rd of a can of 'start ya bastard' ether spray.
Occasionally it backfired a litte, and a fair few times it almost ran. Almost. Clean the plugs, air the engine, try some different settings, try again... and again and again all day. My back still hurts from all the cranking.
Next time I am going to lug out the battery from my truck with the hope that the extra speed of turning the engine over will get it to fire. It felt like a bit more crank over speed might have done it. I have a feeling that once I get it running it will burn out the damp old cobwebs from the engine and will actually allow me to tune the carby on the fly in order to get the settings a bit better.
If this doesn't work then I am going to have to try to free the seized-up tiny little slotted screw on the end of the maggy drive shaft, facing away from me, right up the back of the engine in the really inaccessible bit, and start blindly playing with the timing a little bit (the timing marks on my flywheel are rusted off
It is such a simple engine, and the people who get them running well can start them with a hand flick of the flywheel. Mine has never done that and has been the bane of my boat ownership- but no doubt it is something really really simple.
Anyway, back to bikes.
I just tried Rucksta's suggestions and there is no perceivable play in the shock mount or anything else other than the final drive.
With the final drive empty of oil, rolling the wheel forwards and backwards produces a very slight difference in sound. Forward just sounds like a smooth rolling bearing, backwards introduces a very slight rumble. I am only hearing it because I am actually looking for it and all this is with my ear as close as possible to the final drive, ie it is very quiet.
just to open up and have an investigation within the final drive, then put it back together does one need new gaskets or seals or anything?
Work ran late tonight so I couldn't get much done, but I must say I am absolutely loving having a TIG welder.