Please explain transmission types?

zer037

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Apr 25, 2020
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I am looking at several different 49cc 4-stroke kits for sale on amazon and they have a belt drive a double chain drive and a single chain drive.
I live in an area with no hills here and I weigh about 165 and would prefer speed over torque.

There is a video in youtube from bikeberry that says the double chain has a 6.8:1 gear ratio and is better quality but slower than single chain drive and the single chain has a 3:1 gear ratio but is faster than the double chain. I believe the 3:1 would be faster top end speed.
I have no idea about the belt drive though.

How can I get one of these transmissions to go close to 35+ mph constant speed?
Can the double chain go 35+ mph constant?

Which one is better regarding longevity?
Which one is better regarding torque?
Which one is better regarding speed?

Also I have a tecumseh H35 motor in great condition; what transmission will fit on this motor?
 
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LR Jerry

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Dec 19, 2011
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Not trying to discourage just trying to determine what your intended use is first. If you plan to only off road more options are available. Otherwise to be street legal you'll have to meet moped requirements.
 

LR Jerry

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Dec 19, 2011
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The 4G belt drive is a fairly good one the chain drive ones are mainly junk. Though one can replace parts in them with better components. There's also some low grade belt drives as well.

These transmissions are reduction drives. It's a combination of total reduction which will be a factor in determining speed. For example: If max horsepower is at 7000 rpm on a particular engine and total reduction was 20:1 then the rear wheel would turn 350 rpm. If the wheel was 26 inch diameter wheels the top level ground speed would be 27 mph.

If you only plan to off road or track race there's several engine choices and set ups one could go with to obtain 35 mph.

Many here can tell you Florida is a state which is very strict on motorized bicycles. To be street legal you'll have to be 50cc or less and pass an inspection by your local DMV that your build is meeting moped requirements. If you don't meet these requirements any time you go for a ride you'll risk a fine and/or being impounded.

Realise I'm trying to be helpful here.
 

zer037

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Apr 25, 2020
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What is the gear ratio of the 4G belt?
What is the gear ration of the single chain?
What is the gear ration of the dual chain?
 

zer037

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Apr 25, 2020
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These are the kits I am looking at.
Single chain https://www.amazon.com/dp/B082PRXW4D/?coliid=I1SNJBEOWM406R&colid=3LYGUI7OZ0Q8X&psc=1
Double chain https://www.amazon.com/dp/B082W9253V/?coliid=I102GJDDI9O77J&colid=3LYGUI7OZ0Q8X&psc=1
Belt https://www.amazon.com/dp/B087G5TH2Y/?coliid=I1O3OBKQOHQQC3&colid=3LYGUI7OZ0Q8X&psc=1

I understand the concept of gear reduction IE a 3/1 is faster than a 5/1 but a 5/1 has more torque than a 3/1.
They all have 44 tooth sprockets at the wheel.

Do you know what the gear ratios of these transmissions are?
Single chain?
Double chain?
Belt?

My simple question.
I've read somewhere that
The 4G comes in either a 4:1 or a 5:1 gear ratio.
The single chain comes in a 3:1 ratio.
The dual chain is a 6:1 gear ratio.
Is this correct?
 

LR Jerry

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Dec 19, 2011
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Do you understand total reduction? For example if the engine delivers max horsepower at 7000 rpm and you want to obtain 35 mph on 26 inch wheels the max reduction you can have is 15.46:1; which would have the rear wheel turning 453 rpm. If you can give me a particular model and specs on the engine you want to use I can then give you gearing ratios and options for the various transmission you've asked about.
 

LR Jerry

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Dec 19, 2011
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Is this the engine you're wanting to use?

MODEL H35
HORSEPOWER 3.5
2.61 kW
BORE & STROKE 2.50 x 1.938 in.
63.51 x 49.23 mm
DISPLACEMENT 9.52 cu. in.
156 cc
OIL CAPACITY 21 oz.
.62 ltr.
(APPROX.) WEIGHT 25 lbs.
11.34 kg
BOLT MTG. CIRCLE 3.625 in.
90 mm
FEATURES
• Polyethylene fuel tank prevents rust and features a
large, easy-fill opening.
• Soft-pull recoil starter for easy starts.
• Electronic capacitor discharge ignition (CDI) system
for easy starting, even at low pulling speeds.
• Aluminized muffler resists corrosion so engine
remains quieter longer.
• Certified to EPA Phase II, CARB Tier II standards.
• Two-year warranty.
3.5 HORSEPOWER
MINI-BIKE APPLICATION
Part Customer Crankshaft Controls Air Cleaner Style (pg. 2) Oil Drain Exhaust Fuel Tank Top Governed
Number Service Service Part No. Direction (pg. 3) Speed
Part No. Ref. No. Ref. No.
903451B Standard 34734A Mini-Bike 30727 (Paper) Dual Carb. 2 qt. 4000
(Remote) 35974 (Poly) Sides Side (1.89 ltrs.)
Ref. 1 Ref. 4

It's safe governed speed is at 4000 rpm
 

zer037

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Apr 25, 2020
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I want to buy a 49cc kit from amazon.
BUT, I do have that engine you specified the H35 sitting in my garage almost new. and I would like to first buy a 49cc kit with a transmission that would be suitable to take off the 49cc and install in the H35 in the future.
Would the 4G belt, single chain, or dual chain be better for the H35 and would it fit?
 

LR Jerry

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Dec 19, 2011
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Ok with the 49cc engine you'd need to get the 100 splin with the 4G. Then run 11:34 to get the 35 mph on 26 inch wheels.
 

LR Jerry

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Dec 19, 2011
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The 156cc engine shouldn't need a reduction box. You can get a low rpm centrifugal clutch and run a set of 10:40 to a jackshaft, then run 10:48 jackshaft to rear wheel. This should put you in the 35 mph range on 26 inch wheels though with this engine you could run much faster if you wanted to. For 35 on 26 you need a reduction of 8.83:1.
 
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zer037

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Apr 25, 2020
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I think I need some sort of transmission for the H35 to get the clutch sprocket to line up with the rear wheel sprocket.
When I test fitted it in the bike centered the clutch sprocket seems to stick out to much and the chain will not line up with the rear wheel sprocket.

I usually see the 79cc and 212cc predator engines have a transmission that would aline the chain to the rear wheel sprocket.
Jerry I truly appreciate all your help with this. You are very smart.
 

LR Jerry

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Dec 19, 2011
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Your welcome, I was away for a while and lots of new stuff has come out. I'm currently working on modifications to my LandRider derailleur and should be doing a tread on it soon.
1587881374126-1424309393.jpg
1587881374126-1424309393.jpg
1587881449210-1239250307.jpg
1587881449210-1239250307.jpg
 
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zer037

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Apr 25, 2020
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Oh thats cool.

So what transmission do I need for the H35 engine? Would the 4G fit the H35?
 

zer037

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Apr 25, 2020
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So what transmission parts do I need to get the most speed from the H35 and align it to the rear sprocket?
Can you provide me with links to the parts I need?
 

LR Jerry

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Dec 19, 2011
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For your big engine I'm not sure if the 4G will fit to it. However David Staton of Staton Inc has done lots of machine work for me. I'm sure he could design you an adaptor to make the 4G work
 

curtisfox

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Dec 29, 2008
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First H35 has 3/4” shaft, and 49 cc has 5/8” shaft. And some 49’s have tapered shaft, and some straight shaft.
H35 you can by a jack shaft kit from go-kart supply, but then you have to figure how to mount it ?
According to Vince ( Vince motor bikes ) 7G is a better trans then 4G, but both good. Gas bike has the 7G just use PayPal for security. ..........Curt0
 
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