Ok, found a complete pump [without the spiral] & of course it turns both ways & pumps both ways [off the bike] but dropped something--gudgeon pin down there & locks it from turning in reverse as expected. Haven't got a spiral on hand till i turn the farm shed out just to be a smart arse & prove a point--prove me wrong most likely.
Also found a gear change arm of a yz250a which is shorter--'no--it'll be longer in hindsite' so you get a shorter pedal movement. But i need to find the claw arm for same which is shorter to match & give the short pedal travel.

I am no expert but have 5 bikes and rebuilt 4 of the pumps.  The bit with the two pins that can go flying is an overrun type thing that only will drive the gear in one direction.  And to RTs point the ratio is such that the gear teeth are almost parallel to rotational axis and couldn’t drive pinion in either direction even if there wasn’t an overrun clutch 

 

Ahh, but the question must be asked--if you're motor started backwards, would the pump gear slip in reverse due to the ramps at the pins or would it depend how much pressure or resistance it takes to push the oil up the tube. If little force needed then it'd likely carry on as normal. But if its gonna slip around the pins then ya better premix it. Na--don't run it backwards as it'll hemorrhage big time if ya touch the kickstart--split the cases. I've seen it happen at a motocross start gate but on a Husky in the late "60's in NZ. Was JN Roberts who was racing here from the US. No damage done but he was last out of the gate by the time he restarted it haha. Fun time those.

That is an interesting question, I never thought about the engine running backwards but if you say it can then I believe you!
I guess whether the pump would put out would depend upon friction relative to load between the pins and the inside of the ring gear with the two opposed steps, and the load to pump oil in reverse rotation.  Issue I would have is that I would have to sit on the bike facing backwards to ride it and that I would have issues working a right hand shift and a left hand brake and would kill myself!

I have an oil pump with the drive worm gear shaft with plastic drive gear inserted in the pump body but off of the engine. If I hold the pump and turn the plastic drive gear that engages the crankshaft primary gear in the direction that it normally turns the pump shaft will stroke in and out. I can feel slight resistance. If I turn the plastic drive gear in the opposite direction it turns with no resistance and the pump shaft does not stroke. The priming wheel turns in it's normal direction with the arrows while the pump drive gear turns in it's normal direction. The priming wheel does not turn if the drive gear turns backwards. So it is likely that the pump is not delivering oil if it is turning backwards.

I had a '72 RT2MX back in the day that the engine frequently ran backwards when it backfired while starting or stalling at slow speeds. Caused several episodes of excitement, embarrassment and terror.

Well that proves it then & thanks 1971DT250. Great answer msavitt. We should have a backwards race lol. Riding backwards to Xmas. My bsa bantam 125 started backwards when rolling back down a small hill 65 years ago lol, so i road it home backwards about half a mile to show dad haha.