KZ440 no start, no matter what

Hi. I'm trying to get a KZ440 running and it doesn't seem to catch no matter what.
When I first bought it, it ran very roughly with no filters or intake box (just to make sure it ran). Last week, it would only idle very roughly and would die if I tried to rev it. I did get it to rev up a couple of times, and once it got to 3K or above it would stay there fairly well. Now it only cranks and very rarely spits gas back through the carbs, and the crankshaft seems to kick backward sometimes.

I'm getting a strong spark at the plugs and visible spark on the points breaker.
I've checked all the wires and cleaned contact points on the whole bike.
Points are set dead on.
Coil resistance is correct. Ign coil is brand new Emgo, the right resistance for points (not the electronic ign).
Battery is new. Plugs were swapped from a well running KZ400. No change. 400 runs the same on either pair.

Carbs are freshly cleaned with new diaphragms. Slides operate correctly.
Tried a second set of freshly cleaned carbs as well. Same symptoms.
Can't swap the KZ400 carbs because they're too small for the intake.
Jets had already been increased from #35 to 40 pilot and from 88 to 92 or 95 on the mains.
Choke seems to makes no difference.
Gas is fresh. Cutting off the gas and using starting fluid makes no difference.
Pilot screws in to 1/2 turn or out as much as 5 turns makes no difference.

There is some oil seepage between the right side jug and head, but compression was 150 left, 143 right. I don't have and can't borrow a leakdown tester.

I can't imagine this is good for the engine, but here is the crank kicking back and forth (sometimes) as I crank it over:


What else can I check?
Is there any way to verify the cam timing without taking the valve/cam cover off?

Thanks in advance for any help.
Hex

The engine did run, even though poorly. Later the engine will no longer start. In between those 2 conditions, did you do anything at all to the points such as clean the points cam, adjust the points, or any other similar action? Ed

Aside from swearing at it, putting in more gas, taking off the center stand, and redoing the front brakes, nothing I can think of.

Valves adjusted?
Steve

Steve, I checked but did not change them. They are within spec when cold. The valves appear to open and close at the right time according to the crankshaft and piston movement, but I couldn't say the chain hadn't jumped a tooth somehow. Good compression though.

Clean the points again. I use a points file then a folded matchbook to get the grease off them. Starting fluid?
Steve

I had a strong spark at the plugs. Dressed them again, no change. Starting fluid doesn't seem to change anything.

Pic of plugs?
Steve

I'm not sure plugs say much about an engine that isn't igniting, but I think they're carboned up from poor ignition before and now wet with gas from lack of ignition.

I'd get new ones.
Steve

I will to tune it once it's running. They aren't the problem though. They spark bright and blue, and they run fine in the other bike. My 400 runs the same on 3 sets of plugs now, and the 440 misbehave the same on all the same plugs.

I think the engine kicking back is a big clue. Points break right on the F mark though and the plate is fully retarded, so I don't see how it could be igniting too soon and kicking back from that.

Compression , fuel, spark which one are you missing?


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