just rebuilt my atc70 and now no start

[Roby466]

I just rebuit my atc 70 1983. Quite the rebuild... crankshaft, engine case, head (all used but good) and now it won't start...
Compression seems quite good when I crank it.
There is good spark. I checked the cam timing and it looks good (when flywheel is at T, the O is on the far end of the head)
Gap appears good on the point and spark is good. Fuel makes it in the cylinder as after cranking like a crazy mo... the spark plug gets wet and I can burn the vapors from the cylinder. What drives me crazy is that there is nothing... it doesn't even fire a bit...
What does the neutral safety switch do? How do I bypass that? *(but given I have spart I would think that the switch is good?)
Thanks for any pointers!
David

[coolpool]

My first action would be to get a number on a compression test. Should probably be around 140#.

[DAM shop]

Are you running the stock air box?

[Roby466]

Better find that compression tester somewhere...
Yep, still the original airbox.
My valve seats were quite rough so maybe the valve is not sealing properly even after the lapping...

[MrConcdid]

my guess is your timing is 180 out of phase. T/F comes up twice per cycle. TDC is the first T/F of the cycle.
Try another spark plug, I had one that would spark outside the cylinder but not under compression.


MrC.

[shortline10]

Cam / timing sprocket is a 3 bolt setup so it’s idiot proof you can’t set the timing 180 degrees out when the O and T are set .



my guess is your timing is 180 out of phase. T/F comes up twice per cycle. TDC is the first T/F of the cycle.
Try another spark plug, I had one that would spark outside the cylinder but not under compression.


MrC.

[Roby466]

Alright!! Started! It turns out the new plug was bad. There was spark but most of the time between the plug body and engine not between the electrodes. New plug and it fored right up!
Now another question. The secondary cam chain adjuster (the one below the engine) how do we know the correct position of the adjuster bolt in there? Tighten until the chain is jot noisy?
Any idea of where to start?
Thanks!
David

[MrConcdid]

So it was the plug, nice.
MrC.