Transmission options for flathead Honda G100



Yellow Perch

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I don’t know how to do gear ratio calculations but if I had a 10 tooth clutch running to a 60 tooth rear sprocket would that work? I would remove the governer so I could run 6000 rpm (stock is limited to 4000)
 

CrazyDan

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You might want a jackshaft to get further reduction. A 9:1 reduction would give you 51.567 mph top speed and might still have good enough torque to pull hills. The g100 is pretty anemic so you might want to go for a higher reduction for takeoff and hill climbing. A 10:1 reduction will pull better than a 9:1 and still do 46.41 mph on a single speed. All numbers are assuming you are running a 26"tire. The 6:1 would be able to hit 77.35 mph if it had the power, but 2.5 hp would never pull that speed unless you had hurricane winds at your back bombing down a mountainside. It takes roughly 4 hp to hit 55 mph on flats with no wind.
 

Yellow Perch

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Jul 7, 2017
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You might want a jackshaft to get further reduction. A 9:1 reduction would give you 51.567 mph top speed and might still have good enough torque to pull hills. The g100 is pretty anemic so you might want to go for a higher reduction for takeoff and hill climbing. A 10:1 reduction will pull better than a 9:1 and still do 46.41 mph on a single speed. All numbers are assuming you are running a 26"tire.
Are they really that bad? Seems like they have better specs than a gx50 that everyone loves? where can I get a jack shaft, I have no welder/fabricating materials and I refuse to buy an EZM
 

CrazyDan

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Are they really that bad? Seems like they have better specs than a gx50 that everyone loves? where can I get a jack shaft, I have no welder/fabricating materials and I refuse to buy an EZM
The gxh50 is rated at 2.5 hp as well. Flatheads seem to not put out as much hp as equal ohc pushrod engines. Check out staton inc for custom jackshafts, my favorite place for custom parts.
 

Yellow Perch

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Jul 7, 2017
Messages
126
The gxh50 is rated at 2.5 hp as well. Flatheads seem to not put out as much hp as equal ohc pushrod engines. Check out staton inc for custom jackshafts, my favorite place for custom parts.
Hm not sure where I got my numbers from. It IS an 80s engine so that’s an excuse of some sort. Hopefully the governor removal will help a little. How much torque does the gx50 have? It is a light little engine and it was free so I cant complain
 
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