There are basically two different types of the more popular, lesser expensive ($100 to $200) jacks, and they are many times both available from the same retailers, that also put them on sale periodically for the $65 to $185 range.
Although people call them the Red or Yellow jack, the color might not actually separate the different designs all the time.
So some confusion exists when just reporting on "a cheap jack".

One design has the same wheel base in both front and back, and uses two foot pedals to raise and lower it and has a somewhat funky mechanism for 'auto-releasing' the locking levers to engage the stops as you raise the jack.
It also has locking levers on both sides that engage at different heights, and is the same basic 'double H frame' design as the more expensive jacks.
In this design there are reportedly two different widths, with the wider ones being obviously more inherently stable.
Sears' example see: http://www.sears.com/shc/s/p_10153_12605_00950190000P
This is similar to the other H frame jacks (like the Torin Big Red jack) but the Sears also has two ***** that lower feet to the floor just behind the front wheels to provide extra stability if needed, where some similar H frame versions, and earlier 'same brand' versions don't.
Point in case ...... look at the Torin at Amazon: http://www.amazon.com/Torin-Jacks-Inc-Motorcycle-Jack/dp/B001CD55YU
and the Torin at the Torin site: http://www.torinjacks.com/ProductDetail.aspx?ProductID=111 to see the differences in the same version of jack (one with screw down feet, and one without) assumedly of different generations.

The second type is a sort of floor jack design that uses the handle to raise and lower the jack (operates just like a floor jack) and may or may not have a more narrow front wheel base than it does in the rear.
The ones with the more narrow front wheel base are not as stable as the ones with the wide wheel base both front and rear (there is a video somewhere on the 'net demonstrating this) but people report it being capable to do what they need.
Sears' example in aluminum (pricier than the above type) see:http://www.sears.com/shc/s/p_10153_12605_00950191000P
To add to the confusion .... there are other versions of the "floor jack design" than the one shown in the Sears link above, that 'do' have front wheel base as wide as the rear.

The ones like the Sears Craftsman that do have the wide wheel base front and back, two locks and two pedals are wide enough and stable enough to do about anything you need to do to your scoot, but IMO they are really not up to having you climbing up on your bike when raised, or for moving it about over anything less than level, smooth, concrete.

If you do work that requires you to climb up on your scoot when raised, or want to be able to easily spin it around and/or push it about the garage all without tying it down, and you need rock solid stability .... then the more expensive J&S/PB jacks are probably what you want.

In any case .... these differences, along with other features of both the different and same styles, amongst the less expensive jacks 'might' explain some of the "mine works fine" and "they are total junk" statements ....... that are posted from credible posters.

I'd put more stock in the posts that describe what work can or can't be done with one jack but not the other, and why that is or isn't important, and solicit model numbers and/or pictures.

I use the Sears Craftsman model number 34612 (double H frame design) and use it to do everything including pulling the front and/or rear ends off my bike.
I don't tie it down for normal stuff like cleaning or fluid changes, but if doing something that causes an imbalance, I do.
On my RKC the difference lifting points with perfect balance is only a few inches, so it requires I stay in that range when using it or I need to tie it down.
It's currently on sale for $79.99 at Sears.
I've only had it since this past spring, but it hasn't let me down in many, many lifts, and up to week long storages, with my bike in the raised position, untied.
If it does do something ugly ..... I will be dealing with Sears, not an eBay seller, etc.

Finally ... I'd 'certainly' ignore the overly dramatic statements like "Jack X killed my entire family when it failed to hyperbolide in the raised position, but at least I saved enough coin on it to pay for the 2010 stimulus package" or "Jack Z stopped a ground zero thermonuclear blast from smudging my chrome, and then sang me a lullaby while it made the sky a lovely shade of mauve".

 

To me the J&S looks like my $65 Pep Boys Big Red jack (that i've been using for around 6yrs...no problems). I tried the Pitbull at a rally, with an Ultra on it, & it was impressive.

 

I've had the Sears yellow jack for two years with no problems. Bike sat on the lift ALL last winter and now it's up for this winter. I do lock it on the stops then release the pump, then engage the pump again just incase.

 

Sears Yellow jack for 3 yrs. with no problems. I sprung for a K&L lift a couple of weeks ago.

 

I have the yellow sears jack and have used on a 04 road king classic and my 08 Ultra classic with no issues. I use it for cleaning purposes as well as maint and tire replacement. I have never had an issue with it.

 

I've used the Yellow Craftsman for years on my Road King Classic with never a problem. I lift the bike for maintenance (including tire removals) and for washing and the jack has always worked flawlessly. Care must be taken to ensure the bike is centered on the lift and balanced, but that is pretty simple and takes seconds.

A buddy of mine has the J&S...he's happy with it, but I have watched him pull his bike off of it once too. Guess some folks put too much faith into a website video...

-Dusty

 

The yellow jack has worked fine for me. I don't roll the bike around on it though. I have pulled wheels and forks on it with no issues.

 

I have a Larin from Sam's wholesale works fine for me . Don't know why anyone would want to strap a bike to a jack . Maybe a lift table but not a jack . IMO

 

Love my red sears jack. Never had a problem with it. Use it for every wash and every service.

 

I've used the Craftsman yellow jack for 5 years, used it on two baggers and a V-Rod, done oil changes and other minor maintenance with no issues. It will be wobbly on the bigger bikes, but it will not fall unless you do something crazy. You can't climb on the bike like you can with the more expensive jacks. If you want to see what they look like in action, all of the jacks, check out youtube and just type in the jack type and watch the videos, apparently this is almost as heated as a debate as what type of oil do you recommend. I use Amsoil or Mobil 1 by the way.