heres that mount. i roll a tube that the id is the same as the od of the downtube cut it in two weld the mount tab to it then clamp it to the frame with industrial nut clamps not the cheesy regular hose clamps. solid!!
The first thing I would replace is the seat. My butt isn't used to a racing seat any more.
I found this graphic that shows both your white version and the current orange version. Besides the obvious color difference, there are some subtle differences in the frame. Looks like your version has a slightly longer wheel base:
Edit: had to post the two images separately, the forums don't support GIF animation apparently.
Yeah, that's what I was thinking.
The price was between $150 and $400 less than other stores for the exact same bike, the shipping is free and I have 90 days to return it if I'm not happy with it. Hard to say no to a deal like that.
Yeah, that's what I was thinking.
Edit: Well, I did it. I pulled the trigger on the orange 29er. Should be here in a week or two.
I very much recommend Gearnut's suggestion w/any U bolt clamp on any bike, steel or aluminum - here's some I made for a shift kit's three rearmost clamps ("pads" later tack welded to the clamps), they've worked very well;
As for motorized aluminum bikes, as with anything I believe it depends on the bike's quality more than the material, specifically the welds and how well the motor has been installed.
While by no means a "top shelf" bike, my first build was a $200 Chinese Schwinn Aluminum Comp, purchased very much because it's beautiful welds & gusseting. While all the peripherals (crankset, shifters, derailleurs etc) have been somewhat annoying due to their low quality & constant maintenance & the single wall aluminum rims so soft as to be hazardous - the frame itself has put up with my abuses for well over seven thousand miles now;
I believe aluminum bikes make for fine motor candidates, the above only a problem as the motor didn't fit within the frame (prolly not an issue w/yers) - so long as care is taken to install the engine properly (no movement), refraining from drilling any additional holes in the frame and doing your best to minimize chafe (partic drive chain)...
That dang Schwinn o'mine jus' won't quit lol & the lessened weight makes for a nice, lively MB.
It's a "generic" 66cc and it's pretty much been jus' the same basic issues we all have, fasteners loosening from time to time (manly head, intake & exhaust) & that is ofc reduced in frequency (but not eliminated) with the use of loctite (blue) lock washers or nylocs (depending on location/heat), and ofc chain wear/stretch. I suspect the compression isn't what it used to be... but there's not been enough of a loss for me to care TBH.
Thanks lol
Engine problems? Well... oddly not many
The "worst" problems I've had w/it is my original NT carby was miscast and developed a hairline fracture (replaced fer less than $20) and I left it sit all one summer as I rode another build, during that time the bearing seal behind the clutch started weeping and contaminated the pads - I just cleaned it out thoroughly w/some carb cleaner and after some use, the seal miraculously "healed" itself and stopped leaking, after another cleaning the pads stopped slipping too
Other than that... tires... lotsa tiresl - tho I s'pose that's got nothing to do w/the engine's reliability lolz
Not that I'm suggesting or recommending it, but just FYI - the first 1500 miles or so I ran the thing on 50:1 Amsoil 'Injector' synthetic, then switched it to 100:1 Amsoil 'Saber' (mixed at about 90:1) - not tryin' to say that's why it's lasted so long... but it doesn't look like it's hurt it's longevity any heh
edit: missed the question of how I made the pads, sorry... they're jus' chunks of "black iron" pipe (typical thick walled mild steel) wthe same ID as my frame's OD, cut in half & ground down a hair to fit, then tack welded to the clamp;
but I gotta say these lil Chinese in-frame kits are a "roll of the dice" ofc, while the Schwinn's keeps kickin' there's no guarantees *shrug* Although they're so easy to work on and replacements so cheap (once "spring fever" is over) that it doesn't really matter... in the case of a major failure I doubt I'd bother fixing the engine, replacing the top end isn't much cheaper than jus' replacing the motor 
