TOPIC:

When my z1100 suffered hydraulic lock the gearbox was full to the brim with a petrol an oil mixture, surprised me when I dropped the oil without realising what had happed, I only had a 4 litre container under the engine and a cigarette on the burn, after emptying the mixture, i I put some cheap 10/40 oil I ran the engine until it was at operating temp then dropped that oil and put the good stuff in never had a problem again

Hi Scotch, Starter was removed from engine, lead replaced starter earthed and both starters worked fine. Re-installed starter, No hydraulic lock up as plugs where removed. Brand new boost battery, engine trying to rotate but not even a quarter of a turn. ? so you can see where I'm going with the starter clutch.

Gavin, plugs out no sign of petrol. Also pingel tap fitted.

Ok - got all of that, but.....When the starter turns the engine over that -1/4 turn: Does the engine "lock-up" or is it the starter clutch that slips or disengages?

I'll just jump in at this time. I think the right thing to do now would be to remove the right cover and turn the engine by hand (with plugs out of course). If it feels free, remove the left cover and take a look at the starter clutch when cranking. I'd also make sure all the ground connections (including to the frame) are clean. What's the voltage drop when cranking? The starter might turn but have not enough 'juice' to finish the job. After this done and still no answer - investigate further. And that might be removing the cam cover and see how the chain feels. Does the wheel turn free in neutral?

I would follow Stan's plan with removing the right cover and turning the engine over by hand. If it does lock up then pull the cam cover and have a look at the cam chain, timing marks on the cams and also look down the rear cavity for the nylon gear on the tensioner for the cam chain. If the cam chain was loose the cam timing may have jumped a tooth and now a piston has hit a valve.