The day finally came thanks to a visit from the Wife's best mate and her new partner - someone strong enough to push the powered starter up to the CR750 and a chance to start her up.
First job - check the oiling. Bike in fifth gear and the plugs out, ignition off and spin her up. It's all looking good, with the oil cap up, the tank emptied - but would it return? Well after a few cautious seconds, it did. Not a torrent by any means but more than a trickle. I think the deep sump means I need a bit more oil in the tank but otherwise it seemed OK. Oil pressure was low at only about 20lb/sq inch but nothing untoward happening so I thought I'd go for a starting attempt.
Plugs all back in, leads on, fuel in and the taps open - flowing nicely through the see through filters and no initial debris which means I cleaned the tank out successfully. Now the first problem - CR31s with ticklers. I've never had a bike with tickler carbs before but was told that once tickled correctly, I should get fuel dripping out of them. I pushed them up and down rather then push in and leave it in for about 8 - 10 pushes and then left them.
Then, off we go, starter cranked up to full and applied to the back wheel, up to speed and dump the clutch. Normal burble for a new engine and then cylinder one fired....but none of the others did. We stopped and took the plugs out, checking for a spark on each one and then for another go...
Back up with the wheel spinning, clutch out and it sounded like it was trying so I opened the throttle the tiniest of bits and it was really popping, but still not catching. The exhausts were popping and blowing infrequent flame as unburnt fuel was lit in them but that's all. The header pipes became too hot to hold but still no starting.
I know the cam timing is right and I was orignially confident that the static timing of the ignition was right. All plugs are sparking nice healthy sparks which means one of three things - fuel not getting through (plugs were moist but not running wet with petrol), fuel from my jerry can was too old (it's a few weeks old but not ancient), or the timing of the ignition is out.
I think I need to check all three things starting with the timing. Anyone have thoughts on what theythink it might be? The wife took some video so when she's uploaded it I'll post it on - may take a month or so! Back to the drawing board in the meantime, rats!!