planning a build

[Sidewinder Jerry]

I have been heavily considering a 4 stroke project for my next bike. As a long time 2 stroke person I have had to do a bit of research myself.

If there is any flexibility in your budget and you have the aptitude to learn, you can piece together your own setup to your needs for not much more than most quality 4 stroke kits. This will allow you to bypass some of the issues you are likely to run into with your project.

Much like the cheap 2 stroke kits, the cheap 4 stroke kits have their own brand of "tweaking" that needs to be done to really make them good. It's nothing too difficult if you have some basic mechanical skills and can use tools with some level of competence.

My personal choice for a transmission would be the dual chain drive sold by Grubee. Not just because it's more affordable, but I trust the durability of a double row chain drive, and I like the design of it too. The driven sprocket has a freewheel on it just like the belt drive kits and both the drive and driven shafts are supported by ball bearings on each side of said sprockets. It will be a it louder due to the chains and sprockets, but I can live with the cost of noise for a more durable design.
Link https://www.grubee.net/collections/4-stoke-bike-engine-items/products/dual-chain-gear-box

Your speed goals are nice and realistic, and consider this, most legal e-bikes have a throttle only top speed of 20mph, so even with a 5:1 reduction transmission you will likely at least top that, all while being able to climb hills easier. Unlike the 2 stroke kits, the forced air cooling of the 4 stroke engines also means you don't have to worry too much about overheating anywhere near as much as the 2 stroke guys.

Do you know what the reduction is on the Grubee duel chain drive is? It looks like 3\1???

 

[Sidewinder Jerry]

I have been heavily considering a 4 stroke project for my next bike. As a long time 2 stroke person I have had to do a bit of research myself.

If there is any flexibility in your budget and you have the aptitude to learn, you can piece together your own setup to your needs for not much more than most quality 4 stroke kits. This will allow you to bypass some of the issues you are likely to run into with your project.

Much like the cheap 2 stroke kits, the cheap 4 stroke kits have their own brand of "tweaking" that needs to be done to really make them good. It's nothing too difficult if you have some basic mechanical skills and can use tools with some level of competence.

My personal choice for a transmission would be the dual chain drive sold by Grubee. Not just because it's more affordable, but I trust the durability of a double row chain drive, and I like the design of it too. The driven sprocket has a freewheel on it just like the belt drive kits and both the drive and driven shafts are supported by ball bearings on each side of said sprockets. It will be a it louder due to the chains and sprockets, but I can live with the cost of noise for a more durable design.
Link https://www.grubee.net/collections/4-stoke-bike-engine-items/products/dual-chain-gear-box

Your speed goals are nice and realistic, and consider this, most legal e-bikes have a throttle only top speed of 20mph, so even with a 5:1 reduction transmission you will likely at least top that, all while being able to climb hills easier. Unlike the 2 stroke kits, the forced air cooling of the 4 stroke engines also means you don't have to worry too much about overheating anywhere near as much as the 2 stroke guys.

Got a reply from Don the double chain drive transmission is a 6\1 reduction.

 

[ImpulseRocket]

Do you know what the reduction is on the Grubee duel chain drive is? It looks like 3\1???

Got a reply from Don the double chain drive transmission is a 6\1 reduction.

Well, that question is answered at least. I was doing things the hard way and seeing if I could simply find the answer online. I would have tried to count teeth, but they aren't terribly visible under all the grease in the photos.

That may actually work out well for what I was thinking about using it for.

 

[Sidewinder Jerry]

Well, that question is answered at least. I was doing things the hard way and seeing if I could simply find the answer online. I would have tried to count teeth, but they aren't terribly visible under all the grease in the photos.

That may actually work out well for what I was thinking about using it for.

Well it looks an awful lot like the one Bikeberry sells which is 6.83\1.



If it is the same then the small sprocket is only a duel 6t. That doesn't put very mean teeth into the chain. Meaning they'll wear out pretty quick. Bikeberry does sell a duel 6t sprocket replacement.

 

[ImpulseRocket]

Well it looks an awful lot like the one Bikeberry sells which is 6.83\1.



If it is the same then the small sprocket is only a duel 6t. That doesn't put very mean teeth into the chain. Meaning they'll wear out pretty quick. Bikeberry does sell a duel 6t sprocket replacement.

Being a double chain it also spreads the force over more area which should help counter the wear aspect to some degree. Being able to seal off the drive from dirt and grit will also make up for it to some degree as well.

I actually have been entertaining the idea of taking that design and putting a little effort into flattening the two mating surfaces of the 2 case halves and sealing it up with a non-curing sealing Luke Hylomar or the Hondabond that is used for cover sealing (also non-curing). Then a simple fill hole with an appropriate plug can be added so the chains have a gear oil bath. That would also help a lot with sprocket and chain life.

 

[Sidewinder Jerry]

Being a double chain it also spreads the force over more area which should help counter the wear aspect to some degree. Being able to seal off the drive from dirt and grit will also make up for it to some degree as well.

I actually have been entertaining the idea of taking that design and putting a little effort into flattening the two mating surfaces of the 2 case halves and sealing it up with a non-curing sealing Luke Hylomar or the Hondabond that is used for cover sealing (also non-curing). Then a simple fill hole with an appropriate plug can be added so the chains have a gear oil bath. That would also help a lot with sprocket and chain life.

This one has a good look to it. However, I have no idea what they mean by adjustable or any real useful information on it.

AD Adjustable Dual chain gear box transmission - 49cc 4-stroke gas motor engine | eBay

AD dual chain adjustable transmission gear box for 49cc 4-stroke 76/78mm tapered clutch engine. ( it also can replace the single chain gear box or 76/78mm tapered belt transmission).

www.ebay.com

 

[ImpulseRocket]

This one has a good look to it. However, I have no idea what they mean by adjustable or any real useful information on it.

AD Adjustable Dual chain gear box transmission - 49cc 4-stroke gas motor engine | eBay

AD dual chain adjustable transmission gear box for 49cc 4-stroke 76/78mm tapered clutch engine. ( it also can replace the single chain gear box or 76/78mm tapered belt transmission).

www.ebay.com

I actually did like the look of that one, but the lack of any information makes it a bit difficult to determine if it would be useful or not.

 

[ImpulseRocket]

I said screw it and ordered that transmission as I do like the case design over the others I have seen from a durability standpoint with it's extra bracing and larger looking outer case design. I will find out for myself what it has to offer and what the adjustability is. I suspect the driven sprocket inside the housing has a slightly eccentric mounting system - note the 4 bolts on the back sprocket side of the housing. It looks like the bearing for the shaft is a hub that bolts in place, and when the hub is rotated counter-clockwise it may tension the chains inside the transmission.

Even if it ends up being a general waste of time, that design does somewhat open up other up potential options for experimentation. Specifically, with that rear drive looking to be a hub assembly, and the part the 4 bolts go through also appears to be a removable section, the entire back side looks like it could be opened up, and that would make room to potentially make some sort of mount to integrate the S3X hub directly into the transmission design, greatly reducing the complexity of trying to integrate the hub into said design.

 

[robe]

I believe adjustable means that the final drive is on an eccentric cam so the center to center distance can be changed by rotating the bearing housing against the mounting plate.

Drives me around the bend they don't show the guts nor the sprockets under the cover. If I was trying to sell stuff like this all measurements and angles would be shown.

 

[ImpulseRocket]

I believe adjustable means that the final drive is on an eccentric cam so the center to center distance can be changed by rotating the bearing housing against the mounting plate.

Drives me around the bend they don't show the guts nor the sprockets under the cover. If I was trying to sell stuff like this all measurements and angles would be shown.

Well, never fear, I will do that once this thing arrives. The lack of information on a lot of these types of parts is endlessly annoying. Worst case scenario, it won't work for me and I can just turn around and sell it.