Top Speed of Belt Drive Chinese 4 Strokes

Mike St

Active Member
Joined
Jun 16, 2008
Messages
499
I'm posting this because some on the net are claiming 35mph as top speed
on these 4-stroke kits equipped with belt drives.
Assuming the belt drives are 5:1, here's the calculated top speed on a 26 inch bike:
44T rear sprocket, 10T drive sprocket = 25 mph
41 rear sprocket, 10T drive sprocket = 26 mph
36T rear, 10T drive = 30 mph

I see a friction drive as a better option, powered by a GX50 Honda.
With a staton drive equipped with a 1.5 inch roller, top speed is 31mph.
All the power is applied to the wheel with no power losses caused by
transmissions or vibrating chains.
For more speed, and noise, a user can select a 2 stroke Zenoah G43L capable of 12,000 rpm.
At 10,500 rpm a friction drive Zenoah with a 1.34 inch roller, top speed is 41mph.
https://www.davesmotors.com/zenoah-g430rc-g43l-42cc-complete-engine-ga41046

The fricton drive is extremely attractive for motorizing a bicycle, and capable of mounting
to any bike.
 

Wrench

Well-Known Member
Joined
Nov 14, 2018
Messages
3,464
I'm posting this because some on the net are claiming 35mph as top speed
on these 4-stroke kits equipped with belt drives.
Assuming the belt drives are 5:1, here's the calculated top speed on a 26 inch bike:
44T rear sprocket, 10T drive sprocket = 25 mph
41 rear sprocket, 10T drive sprocket = 26 mph
36T rear, 10T drive = 30 mph

I see a friction drive as a better option, powered by a GX50 Honda.
With a staton drive equipped with a 1.5 inch roller, top speed is 31mph.
All the power is applied to the wheel with no power losses caused by
transmissions or vibrating chains.
For more speed, and noise, a user can select a 2 stroke Zenoah G43L capable of 12,000 rpm.
At 10,500 rpm a friction drive Zenoah with a 1.34 inch roller, top speed is 41mph.
https://www.davesmotors.com/zenoah-g430rc-g43l-42cc-complete-engine-ga41046

The fricton drive is extremely attractive for motorizing a bicycle, and capable of mounting
to any bike.

They probably do hit speeds of 35 mph. Road conditions vary.
A slight 1% down hill or riding with the wind will increase your speeds.

I know a friction drive is your favorite. Share your build with us(y)
 

mark20

Well-Known Member
Joined
Sep 26, 2018
Messages
2,139
The main problem with friction drives bikes is once there's been light rain or snow the roller slips and makes it useless for anything other than noise.

Rear tires also get chewed up, you limited to a road style tread or a full-on slick (Mtb pattern will make it bumpy and even make it slip more)

if you go offroad it'll start to slip due to the dirt and rocks that get between the roller and the tire. Reducing top speed and increased heat.

limited gear ratios and engine options, etc etc.

But my cheapo Chinese 4 stroke would do about 34ish, had a pod filter and made my own exhaust for it, also had a 212 carb.

great runner and never left me stranded, however, that stupid clutch bushing is the Achilles heel of it.
 

Mike St

Active Member
Joined
Jun 16, 2008
Messages
499
You obviously didn't have a stock Chinese 4-stroke. I should have made it
clear I was talking about stock. Tire wear is not a real consideration if the
pressure is kept up, but you're right, friction drive and most four strokes
are not really designed for off-road. You're right on riding
a friction drive in the rain or on a wet pavement, which I don't plan to
do.
 

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JerryAssburger

Active Member
Joined
Apr 20, 2017
Messages
155
As soon as mine is broken in, I'll give it Hell and see what I come up with. It is absolutely stock, with the exception of the 32T on the rear wheel. I am a 230 lb Fat Guy and I'm running the stock 26 x 2.125 Cranbrook tires. Right now it hits 30, and I back off because the thing barely has a couple of hours on it. I'm interested in seeing if it will exceed the 6800 rpm that the 49cc motors are limited to.

If they ever found a way for the 2-strokes not to be so danged noisy and call attention to themselves, I'd think that would be an option. I think the new "Mellow Power" YD100 and Zeda 80's are a step in that direction. One of the better things for this hobby is NOT to piss people off or get the attention of the authorities. I'm sure all of you have seen the Project Farm youtube video of the 2-stroke vs 4-stroke bicycle kits compared. The section where the bikes are both doing 35mph-ish.... that Gawdawful Droning of the 2-stroke always has me muting the volume. I'm sure it's just me, but it's the equivalent of a blender set on Puree strapped onto the bike.
Sorry- this Plandemic has had me in a "rant-y" mood lately! :)
 

JerryAssburger

Active Member
Joined
Apr 20, 2017
Messages
155
I'm posting this because some on the net are claiming 35mph as top speed
on these 4-stroke kits equipped with belt drives.
Assuming the belt drives are 5:1, here's the calculated top speed on a 26 inch bike:
44T rear sprocket, 10T drive sprocket = 25 mph
41 rear sprocket, 10T drive sprocket = 26 mph
36T rear, 10T drive = 30 mph

I see a friction drive as a better option, powered by a GX50 Honda.
With a staton drive equipped with a 1.5 inch roller, top speed is 31mph.
All the power is applied to the wheel with no power losses caused by
transmissions or vibrating chains.
For more speed, and noise, a user can select a 2 stroke Zenoah G43L capable of 12,000 rpm.
At 10,500 rpm a friction drive Zenoah with a 1.34 inch roller, top speed is 41mph.
https://www.davesmotors.com/zenoah-g430rc-g43l-42cc-complete-engine-ga41046

The fricton drive is extremely attractive for motorizing a bicycle, and capable of mounting
to any bike.
AGREED. The claim(s) of the budget 4-stroke t-belt kits hitting 35 with the gearing they come with? You'd have to wind it out past 10000 rpm. THEN there is the question of, are these REALLY 53cc un-restricted engines? Probably not. Right now, mine is geared so that if I exceed 33mph, I will be above the 6800 rpm limiter. I will post my results as soon as I find out.
 

Sidewinder Jerry

Well-Known Member
Joined
Mar 14, 2011
Messages
2,256
If you're going to use a Staton system instead of a tire wearing friction drive with a single ratio; build a rear rack build. Then run it through a Staton triple chainring shift kit.

18.75:1 gearbox, 15:44 drive ratio, chainrings 28,36,44, custom 7 speed freewheel (34,28,24,21,18,15,13) reduction 66.79:1 to 16.25:1.

Shift system

Red gears: 1(1-3)
Hill climbing, load pulling.

Yellow gears 2 (3-5)
Around town general use

Green gears 3(5-7)
Open road use.

The only time a chainring is shifted is when either in sprockets (3) or (5).

All shifting is done with the left hand.
20210420_203410.jpg

Resized_20210419_140043.jpeg
 
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MotorBike - Wayne

Moderator
Staff member
Joined
Apr 23, 2020
Messages
1,213
^^^ I would NEVER ride that bike... If that chain ever broke.... Your lower leg would be in a world of hurt.
And what about if your clothing got caught in that chain ?. = BAD design.
 

Sidewinder Jerry

Well-Known Member
Joined
Mar 14, 2011
Messages
2,256
^^^ I would NEVER ride that bike... If that chain ever broke.... Your lower leg would be in a world of hurt.
And what about if your clothing got caught in that chain ?. = BAD design.
Guess you didn't notice the chain guards. I don't buy junk chains either; been riding a set up like this for more than 11 years, never had an engine drive chain break. I have a tachometer, so I know exactly what my engine is doing and when to shift gears. Much better than the listen and guess method, hope you get it right.
 
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