Engine Sprocket
We have several rear sprocket possibilities for our customers to “fine tune” their gas 
operated bicycle to accomplish their desired optimal rate/power gear ratio.
A note to remember: The larger the rear sprocket, the slower the bike will move, but will have power to climb hills. The smaller the rear sprocket, the faster the bike will move, but will climb hills much less successfully. You are trading power for quickness or vice versa.
You can expect sizes of 36 tooth, 44 tooth, 48 tooth, and 56 tooth sprockets in the Large 9-hole gear. The internal diameter is definitely 1.4", hole spacing can be 1". Observe table below for specs. Commonly, the large 9-hole sprocket with 48 tooth configuration should come with the 4G Engine Sprocket china T-Belt Drive 4-stroke engine kit.
Rear Sprocket (Large 9 Hole) Hole Spacing Internal Diameter Outer Diameter Best Speed Acceleration/Power Included With
36 Tooth 1" 1 13/32" 5 7/8" Fast Low Sold Separately
44 Tooth 1" 1 13/32" 7" Moderate+ Moderate- Sold Separately
48 Tooth 1" 1 13/32" 8 1/8" Moderate- Moderate+ 4G T-Belt
56 Tooth 1" 1 13/32" 9" Gradual High Sold Separately
The tiny 9-hole sprockets come in two sizes, 44 tooth and 50 tooth. The internal diameter is definitely 1.39" and hole spacing is 1". See table below for specs. The tiny 9-hole 44 tooth sprocket will come with the SkyHawk Position Fire 2-stroke engine kit.
Rear Sprocket (Small 9 Hole) Hole Spacing Internal Diameter Outer Diameter Top Speed Acceleration/Power Included With
44 Tooth 1" 1.39" 7 1/8" Moderate+ Moderate- SkyHawk Angle Fire
50 Tooth 1" 1.39" 8 1/8" Sluggish High Sold Separately
We also carry 5-hole sprockets in 44 tooth, and 48 tooth sizes. The internal diameter is certainly 2.5" and the hole spacing can be 2". Outer diameters are 7" for the 44 tooth and 8" for the 48 tooth
Rear Sprocket (5 Hole) Hole Spacing Inner Diameter External Diameter Top Speed Acceleration/Power Included With
44 Tooth 2" 2.5" 7" Moderate+ Moderate- SkyHawk Angle Fire
48 Tooth 2" 2.5" 8" Moderate- Moderate+ Sold Separately
We offer a 6-hole sprocket in 36 tooth, 44 tooth, and 50 tooth sprocket sizes. Internal diameter 1.8" and hole spacing of just one 1.5". Outer diameters are 5 7/8" for the 36 tooth, 7.25" for the 44 tooth, and 8 1/8" for the 50 tooth
Back Sprocket (6 Hole) Hole Spacing Inner Diameter External Diameter Best Speed Acceleration/Power Included With
36 Tooth 1.5" 1.8" 5 7/8" Fast Slow Sold Separately
44 Tooth 1.5" 1.8" 7 1/4" Moderate+ Moderate- Sold Separately
50 Tooth 1.5" 1.8" 8 1/8" Slow High Sold Separately
We provide a disc brake sprocket that bolts to the brake rotor hub in a 44 tooth sprocket. Internal diameter is certainly 1.29" and hole spacing is 1" with an outer diameter of 7"
Disc Brake Sprocket (9 Hole) Hole Spacing Inner Diameter Outer Diameter Top Speed Acceleration/Power Included With
44 Tooth 1" 1.29" 7" Moderate+ Moderate- Sold Separately
Ever-power Engine Sprocket Shaft
Description
Description for Ever-power Engine Sprocket Shaft
• Pins and shafts are machined from super-hard, aircraft-rated Durabar 60 metal and bearing surfaces are ground to a 16 micron finish
• Deep heat-treating provides 60-63 Rockwell hardness and CNC machined tapers guarantee concentricity within .0003″
• 3-hole crank pin design distributes oil equally to both rod races
• Annealed threads on shafts allow torquing up to 100 ft. pounds. over the OEM specifications
ENGINE SPROCKET, 13T
This sprocket was originally made for the Yerf Dog Spiderbox GX150. It will fit most GY6 engines without reverse.
In case you are choosing to eliminate a reverse box instead of replacing it, you can use this sprocket to do away with the whole setup cleanly.