have any of you used a small goped engine?

[dchevygod]

I've seen the 46cc engine used on an MBC but not the 31 or smaller. The 29cc RC motor on ddm makes 3.5 hp @ 14000rpm stock! The 460 is 4.2 hp @ 13000rpm, I'm almost done with a gebe based belt drive for my bike. I used a billet goped motor mount, a FD u bracket, some spacers , gebe belt and sheave and 2 14-15t 5m belt pulleys that just need to be lathed to fit on the clutch from ADA racing I'm using. The mount is really clean looking. I used a turnbuckle to adjust belt tension so ther isn't any side support struts. I need a motor, fuel tank and throttle! My schwinn scooter with a goped engine got stolen and I'm without a ride untill I finish this build. I will get pics asap. Any comments or concerns with using a high output 29cc engine? I'm open for all feedback good or bad.

 

[dchevygod]

pics

Try this

 

[5-7HEAVEN]

Sorry your bike got srolen.

Was that the one you were working on the friction drive? The one with a 460 engine?

Your link does not have any MB pictures.

 

[dchevygod]

Sorry your bike got srolen.

Was that the one you were working on the friction drive? The one with a 460 engine?

Your link does not have any MB pictures.

Thanks bud, it was this http://www.youtube.com/watch?v=dJmbyG57rY8

Not my motobecane no but i did have my brand new 460 on my Schwinn custom scooter it had 3 tanks thru it. And the Geo i spent so much time Modding got snagged as well.

 

[5-7HEAVEN]

The Geo on Youtube? That's criminal!

The 460 and the Geo gone.....sad.

 

[HeadSmess]

solid mount, with quick release. i like.

though its an idea to weld some bar to the plate inside the seat stays.(or outside...whatever) stops it from twisting and or slipping... and some sorta brace across the u-bracket... as a comparison, put a knife between the tines of a fork and twist...they bend easily, and the further out the bending force is from where its clamped down...the easier it is to bend. from what i can see, the pivot looks roughly 4 inches across, and the whole lot is dangling out about 6 inches... and the steel its made from looks like 1/8 or 3/16 mild gal. not reknowned for its hi strength!

theres an amazing amount of torque involved, and while it may feel solid when you thump it, its invariably very flimsy when youre about 30km from home with no tools! especially after having hit a mega pothole!

glad i dont live in a place like that... i leave my keys in my ignition, dont lock my w'shop doors, heck, havent closed them in 3 years! things only go missing when i forget to pick up and need them in 6 months or so

 

[dchevygod]

Welding isn't an option, its an aluminum frame. So i will use one piece of aluminum flat bar from the seatpost clamp to the top bolt of the billet mount.

 

[HeadSmess]

no, no, no.

the u bracket is bolted on, if my eyes arent decieving me.

theres a lovely little triangle composed of the two seat stays and usually a cross piece for mounting a reflector or something.

what im saying is weld to the face of the UBRACKET, some bar that neatly engages with that seatstay triangle! then the ubracket cannot slip, be it up, down, or side to side. its always going to end up in the same place when you pull it off...


and a simple plate across the top of the ubracket so it doesnt twist itself up.

all welding done to that u-bracket. nothing else.


and if the frame is aluminium...DEFINITELY put something in that triangle! those seat stays take your weight, the engines weight, plus g-forces! go adding a vibrating engine.... it needs to be solid. hospitals smell funny and the beds arent very comfy

id be going as far as slicing a tube in half, running them at least six inches up the stays, then welding the ubracket to them...spread the load as much as possible!

think of a coke can...you can stand on one... but as soon as it gets a slight dent or you jump on it or stomp on its side, it collapses. now picture your seat stays as a coke can...designed to accomodate weight and a bit of bouncing...not hi frequency vibrations from a fast revving engine!

 

[dchevygod]

Oh I understand, actually the triangle has a hole that the center bracket bolt goes thru. If you understand what i mean it does basically what you just described. About the extra support on the bracket that is a good idea but this material it's made of is strong. I'm not thumping on it IM leaning on it with all my weight and it only flexes the frame an 1/8" if that. Ill take your words to heart though, with the spacers it really doesn't twist either i tried with a prybar and not much movement.

 

[HeadSmess]

just one bolt through the centre/U bracket? what stops it from rotating on said bolt? dont say tightening the bolt cus ill say...aluminium crushes


just nice to be aware of these things so that in six weeks of hard use youre not back in the shed... or even 6 minutes, sometimes... (always check and tighten bolts before testing.... )