This is an old subject covered well in other threads and forums so don't want to start another debate on it. But just try and help you out with your options, there are guys that swear by the J&S lift. And it is a very good lift (with a very steep price) here is the link if you want to look at it.
Big Wheel Motorcycle Lifts - JS Jacks
But myself personally if I spent that much money on a lift I'm gonna get a full-fledge table lift like you see at the pro shops. With the money I had, I went with Harbor Freight lift and it has served me well many times. Love my new Harbor Freight bike lift. Got it for 80 bucks on sale. Sometimes they run these for $69 bucks. You have to swap to braces to the outside though to miss the Dyan's oil pan that sticks down below the frame. Here is how,
(Please excuse lawn mower handle in picture at left)
Had to do the Dyna Modification to it, which basically is moving the pads to the outside of the lift braces to allow room in between for the Dyna oil pan that sits below frame.
Keep your old bolts and buy the extended warranty (it's less than 10 bucks) my jack started leaking just a littel later and I had to switch the pads back when I took it back and they gave me a new one. (I think it started leaking after I jacked it all the way up with nothing on it once)
NOTE: Keep kickstand down and hands on handlebars when lowering. If you don't press the foot lever the exact amount it will come down pretty quick. I usually press the lever all the way down and have never had a real problem holding bike. One guy drilled the foot lever and mounted a set bolt that would stop the lever at the slowest position (which isn't always at the beginning)
Bought 5 1/2" long 1/2" bolts (drilled out holes a bit) to move the pads. Looks like 5" long would have worked. Just measure your pads to see. I also think the stock dia size would be fine, and would save drilling. Had to cut off the end of bolt by jiffy stand brace ( I could have just turned the bolt around).
Put plywood pads to raise it up a bit so lift pads would miss clutch cable underneath. Put scrape leather strips on plywood to keep from slipping. Holds good.
DO NOT BUY THE ALUMINUM MODEL, I have heard that it sways and is flimsy. It is not even built the same design so I don't know if it could be Dyna modified.
HARBOR FREIGHT BIKE LIFTS
Steel one $89 usual, some sales for $79.
Item # 2792 Manufacturer: Central Hydraulics <-GOOD, LIKE MINE
Aluminum one $More but not as good
Item # 94715 Manufacturer: Central Hydraulics <-NOT SURE BOUT THIS ONE