First Build: 50cc china girl motorized bicycle or axle mount kit

I

interstellarsurfer

New Member
This is my project bike, for the moment:
5608104194_1dd46e62a3_n.jpg

I know it's not ideal, especially for a china girl, but it was sold for $5 due to a mis-adjusted derailleur, so I'm pretty happy with it :)

I've been considering building a moped with a kit for a few years, now I think I'd like to jump in and build one. I've been considering two kits from BoyGoFast, EBay's meh Chinese reseller, and some of the possible pros and cons of each.

50 cc black China Girl
http://www.ebay.com/itm/NEW-50cc-Bike-Engine-Motor-Kit-Gas-Motorized-Bicycle-2-Stroke-Silver-Z50-F-/161091547914 - $145, plus maybe another ~50 for a rack mounted fuel tank

Pros:
- Looks awesome.
- Parts commonly available.
- Bump starting.
- Proper center of gravity.
- You folks love these things, and there is tons of helpful information on them here.

Cons:
- Not sure if it will fit the top tube of my step-thru. Definitely won't fit where it was intended, between the tubes.
- Insufficient drop between the fuel tank and carb, unless perhaps I buy a rear rack-mount fuel tank and rack too.
- I have no personal experience with this type of engine.
- Passive cooling - Not sure if this is actually a problem for these little guys, unless you're idling excessively.
- Roasted chestnuts.


50cc rear-side mounted engine
http://www.ebay.com/itm/49cc-2-stroke-rear-side-wheel-mount-motor-bike-kit-gas-engine-RS2-49-/190737427999 - $200

Pros:
- It's out of my personal space, if you know what I mean.
- Actively cooled, shrouded engine. I've never had an engine of this type overheat, unless the carburetor was failing/out of adjustment.
- No idler pulley. Looks like maybe you can slide the engine to take up slack.
- Possibly more future utility, if I decide to go for a full-suspension mountain bike frame, or get a 4 stroke to mate with the transmission.

Cons:
- Ugly and reduces clearance. Maybe I could mount a toolbox on the other side for a more balanced look, but still not clean looking. I suppose the good news is that I don't have to look at it while riding.
- Pull starting required. Not quite as convenient as bump starting.
- Skews the center of gravity a little.
- Not much real information to be found on this kit, here or elsewhere.

What do you guys think? Is there anything I may be overlooking? I'm hoping to spend less than $250 to get something working well. I don't mind doing plenty of preventative maintenance to achieve reliability, if that's possible.
 
Re: First Build: 50cc china girl or axle mount kit

I once saw a photo of a china girl mounted on a step-through frame. I don't think it was a fake, either. So it would seem that it can, technically, be done.

Still, I wouldn't advise it. You will burn yourself on that engine. And it might not take long. And it might happen often. And there are other issues easy to see and, perhaps, others that are not as obvious.

You could still make it work and it would be a neat achievement. But you probably oughtta take the china girl off the list of possibilities.
 
Re: First Build: 50cc china girl or axle mount kit

I like weird / nonstandard builds - I say go for the chinagirl.... just my personal opinion.

heres an example
2pzd5cj.jpg


It will require a little more skill than most builds - but your frame looks to be a regular v shape so it should actually prove very easy to mount a motor. As for the carb - as long as you dont run the tank very low a very small drop should be enough to feed the carb.

ABout heat:

Well I live in SF - where the hottest ave temp in 2012 was about 75 degrees so its not very hot. BUT I have a high performance exhaust (from a moped) thats about 3-4 inches from my leg - but often much less and I cannot remember ever being burnt. I mostly ride in jeans / pants however.

just my 2 cents
 
Re: First Build: 50cc china girl or axle mount kit

After much consideration, I've decided to try the hub-mounted kit. I plan on ordering it by the end of the month. Perhaps I can contribute a little by documenting the very undocumented kit.

For now, it's off to my local Fastenal to try to pick up a bag of newer, rounder, and less crunchy wheel bearings. :bike2:
 
Re: First Build: 50cc china girl or axle mount kit

Consider a rear rack mount from Staton Inc. Yes the kits cost more but with general maintenance you'll have a bike you'll be riding for years. I've got over 5000 miles on my 5 speed auto shift bike.
 
Re: First Build: 50cc china girl or axle mount kit

Biggest issue I see beside tank mounting is the chain line clearing the rear stays. I have a LaJolla womens cruiser I'm dying to slap a ht on, but the motor mounts so high on the frame that the chain would hit the rear frame stays without major modification.
Check things out before you decide on the ht.
 
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