"Dude:
Your current arrangement in Post #1 looks OK to me - assuming the anchor in the ceiling is secure and the entire thing (anchor, cable, pulley blocks and straps etc.) are all rated for 1000 lb or better. I would always want a factor of safety of
AT LEAST 2.0 on this sort of thing - and a Yamaha 650 weighs around 450 lb give or take....
NOTE: The only change I would make is to move the strap shown in the second (lower) photo from
behind the rear shock to
in front of it.
That way, the strap cannot shift backwards and potentially drop the rear end of the bike on the floor.
The wooden ramp idea in Post #13 also looks promising - recognising that pushing the bike up the ramp might be a challenge... I'd be sure to locate where the bike's sidestand and centrestand pads were going to wind up - and be sure to reinforce those spots very well. Perhaps get some grid plate (see below) and screw it on in each of those places.
On the matter of HF hoists and hydraulic leaks: If your hoist cylinder is leaking - why not simply get a new seal for it. Seals are pretty standard items and come in standard sizes. If you dig the seal out of the cylinder, you can simply take it to an industrial supply house, and they'll sell you a new seal for less than $10. The process would be identical to replacing the seals on a motorcycle fork leg.
Alternatively, you could likely replace the entire cylinder assembly for $50 or less. All you need is a cylinder close to the correct stroke and diameter and suitable end and hose fittings. Exactness is not necessary here - close would be good enough.
Pete
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