Howdy all, it's been a busy time, merry Xmas and HNY!
I've been chasing my tail trying to fix the idle issue, 11 days judging by the last time I posted and this is what happened.
Compression - 145psi +, good spark, battery recharged showing 12.8v, Carb jets set to spec, 91 fuel in the bowl, valves adjusted and checked.
I sprayed starter fluid into the carb with the throttle open then turned her over.
The starter motor cranked away like a champion and the engine pumped and popped but every time I took my thumb off the starter button everything died.
In facebook discussions with locals as well as talks with mechanics at my work I had suggestions of timing, carb adjustments/air-fuel mixture issues, flooded. vacuum and blocked jets.
So I decided to go over everything. Re-cleaned the carb for the dozenth time then tried different variations of jet adjustment, adjusted the float bowl to different heights. No improvement.
So I had a look at timing. Off came the Cam shaft cover, as it so happened the sprocket was 15 - 20 degrees clockwise from TDC. Alarm bells rang and I was confident I had found the problem. I took the cam sprocket off, rotated everything back to TOP/TDC, rotated and checked TDC on crank and cam, checked valve gap, rotated again, checked gap, closed it up and fired away.
Result was ... Worse. A clear pinging sound was now coming from the engine as the inlet valve hit the piston.
Off came the top part of the head, sure enough there was the imprint of the valve left on the piston. I gave everything a quick scrub to remove the carbon then tackled the head.
Removing the rocker pin, I took out the inlet valve and stuck it into my drill. Thankfully it spun even, no bends.
I noticed that even though the TDC mark on the flywheel was lined up, the piston itself still had around 10mm/half inch of travel before it reached TDC.
I made a mental note of this so as not repeat the mistake of rotating the cam too far counter-clockwise.
I took the lower head off, replaced the gasket and seals, slid the piston back in, returned the top head, fitted the cam sprocket and adjusted to be about 10 degrees clockwise of TDC.
Fired it up again, no improvement. The same result kept happening no matter what I was trying. It would fire up, pump away but as soon as I took my finger off that starter button it would die.
This got me thinking about the electrics. More information - I had replaced the handlebar switch blocks with some cheap online ones. The originals had corroded with buttons and switches not working. The new switch blocks worked fine .... except ... the kill switch was inverted.
I had tried all kinds of combinations with the 3 wires that determined the starter switch and kill switch function and the only way to have it perform close to standard format was in this inverted set up. The inversion itself was a physical thing where the red button would only bridge the two wires by clicking up instead of down.
I hope this makes sense.
In any case I had exhausted all the mechanical options I could think of so I decided to hook up the original switch which still had functioning kill switch and starter.
Yup, you guessed it. The bike started and purred like a new born kitten...