ULTIMATE system?


Local time
9:56 PM
Jul 3, 2008
Medford, OR
Okay, guys. I'm really curious what you guys think about this idea. I think it would work, and would be a very sound conversion. My vision is to have a frame-mounted motor that utilizes BOTH front and rear dérailleurs.

From what I've been reading, this will be a culmination of many different systems put into one. So here goes:

We start with any ol' bike.

I'm thinking a good engine right now is to run the 4 stroke Honda GXH50 (http://www.smallenginewarehouse.com...1+5+8+Keyed+Shaft+Overhead+valve+LOS+7000+RPM)

Next, we'll use the clutch from Staton (http://www.staton-inc.com/Details.asp?ProductID=3288)

The gear box and mount will come from the Whopper Stopper (http://www.bicycle-engines.com/49cc-complete-powered-engine-p-156.html)

Now, instead of running a chain to the rear wheel, we run it directly to the front sprocket that we get from here (http://www.cyclone-usa.com/store.php?crn=203) that utilizes a 14 tooth freewheel sprocket, chain wheel, and crankset.

Am I missing something here? Why has this not been done yet? I soon have plans for a GEBE/GXH50 build as soon as the motor comes in from Staton. But I would think this might be a better way to go. Any opinions, comments, suggestions would be appreciated.


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Sounds like a 4 stroke version of the shifter kit from sickbikeparts.com...

...which sounds like a good idea to me.
Um. I am not following. Hooking the engine directly up to the front sprocket seems like you would be forced to pedal at all times, very fast. Is there some kind of freewheel in there somewhere?
Yes, appye. Cyclone-USA.com sells electric motors that mount directly to the bottom bracket which runs the font sprocket. To combat the situation you're referring to, they've designed a front freewheel/crankset combo so the chain is driven but doesn't spin the crank arms on your bike unless your peddle. At least this is what I understand from their website.

Oh, the one thing I forgot to add to this system was a chain tensioner, of course, but I'm sure that wouldn't be difficult to do. Also, thinking more about it, I suppose we could use the 3:1 compact Staton gearbox instead since most of the shifting would be done on the bike. I haven't done all the math, so I'm not sure what the best ratio would be.

I know that these guys:


are at least exploring the idea of a 4 stroke kit which addresses your idea nicely. I have the Grubee Skyhawk II (which I prefer to call it) on a Honda- it's great, but gears would make it more greater!
Houghmade, how do you mount your Honda? Did you make a bracket yourself or find one somewhere else? I have limited metalworking ability so it would be nice if I can find one somewhere that fits the GXH50.

There may be an issue/problem getting the Staton Clutch to work with the Grubee gearbox? The Clutch bell from the chinese clutch would need to be compatiable with the Staton Clutch. As Hough has already said the guys at Sick Bicycle products are currently working on a system to do exactly what you describe, and they are currently marketing a system for the 2-stroke happy times. The other area that adds problems for such a system for the Honda GXH50 is the overall width of the motor, gearbox, & jackshaft, and getting the crankset to clear and still keep the froun sprockets in the proper chainline?

I used the entire Grubee Skyhawk II kit (with my own engine) which includes a mounting plate.
There are two different styles of mounting plates for the Honda gx50
or the Chinese copy of that motor
One is a short plate that will only fit V style bike frames

the other is a longer adjustable plate that fits a cruiser style bike

I have attached a couple of pics of the Grubee kit which show
the engine mounting plate

Right now there seem to not be any kits available and it
will be difficult to just find the mounting plate.

Last pic shows the plate on a felt cruiser

Houghmade, how do you mount your Honda? Did you make a bracket yourself or find one somewhere else? I have limited metalworking ability so it would be nice if I can find one somewhere that fits the GXH50.



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Thanks for the tips guys. I typed Grubee into google and came across an eBay seller who sells the gearboxes, mounts, 105g spoke wheels, and even hubs with dual freewheel sprockets. Say goodbye to bolt on sprockets! I like what I see from this vendor. I don't know why I haven't seen or heard about some of his stuff from this site.

You can find him here:

I've also attached a couple of pics of his sprocket hubs for your convenience.

I think I'm going to send back my GEBE system and equip myself with a nice Grubee gearbox. Anyone interested in a GEBE with a 78mm clutch mount? I guess I should probably list it in another forum. I'll have to give a little more thought before I commit to anything.



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