Scottys bikes

The future of travel, designed and built me.

8 Inch travel, 6 piston brakes, I take this bike to the state downhill track and shuttle myself back to the top.

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you are truly an inspiration
I'm loving the pics

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Let the solution BE the revolution

The commuter, I got this up to 70km/h the other day on a test ride.
This is my first sale, to a mate at work. I fabricated the frame and the gear train. The motor and pedals both freewheel again.

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Ilikeabikea; He'll build a motorbike with a wing
It will be a magnificent thing
Underneath is a boat
So that it will float
And riches to Dan it will bring.......

Scotty,
Your bike are works of art :-)
Could you please elaborate on your reduction gearbox and mounting method utilized on the Honda GX35? Also after having a GX35 in hand, in your opinion is the fuel tank removable and could fuel be supplied by an external tank?
TIA

Sure.
The engine is bolted directly to a 3mm plate which is welded to the frame. This motor wouldn't fit in a standard frame so I designed the teardrop shape to fit it.

The reduction box is an ebay item from a pocket dirt bike, same mount as the GX. Gocart sprockets and chain down to the freewheel jackshaft.

The fuel tank wouldn't fit and is too small for any great distance so I use plastic camping fuel bottles as you can see mounted under the motor. These use the existing lines and filter but the tank must breathe so I drilled an extra hole in the cap I made. I get 100km to the liter at 50 km/h as a rough guide.

These are great engines, perfect for this application, much cleaner than the 2 strokes, about as efficient as you can get too. I have had the carby ice up in cold weather but you would get that with any small engine I guess. I can highly recommend the GX.

Scotty.
Thanks for the info.
My goal is to try to place a four stroke in-frame on a worksman cruiser with a NuVinci rear hub.
I'm now looking at using a Robin EH035. Subaru Robin - Features and Benefits Its lubricating system is such that the engine doesn't need to be upright. Its also built better, cast iron sleeve and so forth. It has the same diaphragm type carburetor as the Honda. Do you think a gravity feed fuel tank would work above these type of engines?

There must be an industry standard for couplings/gears that attach to these class of engines. Can't seem to locate it though. I hadn't even considered pocket bikes until your thread. Again thanks. After searching I found a couple of providers of reduction boxes similar to yours. The covers look different. X7 pocket bike transmission, FS529 gear box, cvt, parts for chinese pocket bikes & Pocket Bike Parts, Gas Scooter, Mini Dirt Bike and Mini Chopper Parts for sale. There's no information on them regarding their actual reduction ratio. If I assume your gear is the same, enclosed chain type, as the above one for an X-7 pocket bike, what was your reduction ratio for planning purposes?

One other question if I may. Are you free wheeling on your jack shaft and just used two right side crank arms on a three piece to gain a sprocket on the left side?

G-Day DasKapitan

The Honda GX35 can run in any orientation also but I was looking at the robin myself for the cast iron sleeve. Either will work with a breathing tank mounted anywhere.
The second gearbox is the one I run, 3 to 1 reduction with a dual chain enclosed with grease. The other one seems to be thinner which may help. Welded straight to the sprocket that comes with the box is a 9 tooth gocart primary then down to an 80 tooth mounted to a freewheel. I only run 9 gears at the back so I used a granny 22 tooth and stepped down the crank with a 16 to 40, swapping the cranks around.
Now when I pedal only, the 80 tooth freewheels and when I motor only the 16 tooth freewheels. I can also run both together which works best as the Honda doesnt have much torque and my legs have plenty.
A NuVinci would work great instead of a cassette as you get a greater range and probably better power transmission I suspect. (I have had some trouble with the chain skipping at top speed in 8th and 9th and it isn't quality related.)

Hey Bud I could use and 69.7cc Expansionchamber.Would you part with the one on the failed frame bike?

Hello Hot Dog, Welcome to the forum