Mounting a engine to a girls cruiser

[WEEDHOPPER420]

You can bolt it right up to a friction drive. https://www.staton-inc.com/store/3....mm-clutch-drum-friction-drive-kit-complete-le

Those pocket bike engines can really scream, but the 1.1/8 roller is a better option if you want to keep the door open for a 4 stroke later down the line.

Are those engines really that strong?
I know they rev pretty high just never really tried one.
I got this one from a friend to do my first build with but had issues with mounting it because of the gearbox and ended up with a used ld100 and its just been collecting dust for the past few years.
How fast would one of those engines push a 170lb guy with a 36 tooth sprocket and 26in wheels... Any idea

 

[cloakedvillain]

Regarding the off center weight: its 5 or 6 lbs for a pocket bike engine and about 8-10 for a 50cc honda. Thats not much compared to a 30lb bike and a rider. I have read that you need a stronger kick stand or those two leg stands to get it to park nice though.

While riding it'd be like sticking your arm out all the time: very minor. Its such a small weight, so close to center. Throw that 6 pounds a yard away you feel it, leverage and all that.

The pocket bike motors aren't spectacular. Stock these are supposed to be around 2 hp, about as strong as a china doll in terms of power, but these do rev much higher. Based on my limited time reading of the pocket bike forums, these rev a good 3-4 k higher.

Redline is close to 11k on these, which means getting a useful reduction gets heavy and big fast. Unless you go friction drive. Which is also cheap and reliable, on top of being small and light.

If you truly must use the crummy chain reduction that comes stock, you need a massive sprocket in the rear. To get an equivalent to a 36 tooth with a china doll you need a 7.2 to one reduction after the stock 3 to 1. Remember: pocket bike engines rev higher for the same power.

Obviously, if I'm reading posts from Pinocchios and the pocket bike engines actually don't rev that high and have more torque than that, less reduction is required.

 

[michael whiteman]

Just create a make shift motor mount with a piece of wood wired on the wheel and hold the motor in position while she tries to balance on the bike. She'll get the idea on the balance issue before you spend more money on something she'll veto later if it isn't perfect.

 

[WEEDHOPPER420]

Regarding the off center weight: its 5 or 6 lbs for a pocket bike engine and about 8-10 for a 50cc honda. Thats not much compared to a 30lb bike and a rider. I have read that you need a stronger kick stand or those two leg stands to get it to park nice though.

While riding it'd be like sticking your arm out all the time: very minor. Its such a small weight, so close to center. Throw that 6 pounds a yard away you feel it, leverage and all that.

The pocket bike motors aren't spectacular. Stock these are supposed to be around 2 hp, about as strong as a china doll in terms of power, but these do rev much higher. Based on my limited time reading of the pocket bike forums, these rev a good 3-4 k higher.

Redline is close to 11k on these, which means getting a useful reduction gets heavy and big fast. Unless you go friction drive. Which is also cheap and reliable, on top of being small and light.

If you truly must use the crummy chain reduction that comes stock, you need a massive sprocket in the rear. To get an equivalent to a 36 tooth with a china doll you need a 7.2 to one reduction after the stock 3 to 1. Remember: pocket bike engines rev higher for the same power.

Obviously, if I'm reading posts from Pinocchios and the pocket bike engines actually don't rev that high and have more torque than that, less reduction is required.

Thank you so much for the information it was highly informative and thank you for taking the time to help me out

 

[WEEDHOPPER420]

Just create a make shift motor mount with a piece of wood wired on the wheel and hold the motor in position while she tries to balance on the bike. She'll get the idea on the balance issue before you spend more money on something she'll veto later if it isn't perfect.

That's a great idea i think I will definitely have to try that thank you

 

[Sidewinder Jerry]

I don't think she'd really be able to handle the enbalance from the weight of the engine hanging off the side like that.
I could but shes inexperienced when i cones to riding motorcycles or even mopeds. I know my wife if she cant do it she'll just say f it and that'll be that .

I have a rear rack Staton Inc kit. The engine off to the side isn't even noticed while riding.

 

[Sidewinder Jerry]

OK, I'm here now to give you some actual useful information about the engine and transmission in question.

The engine produces 1.88 hp at 6500 rpm.

The transmission is 4.7\1 | a China girl has an internal reduction of 4.1\1. So very close to a China girl.

It has a 17t sprocket on it but can be changed to a smaller one.

The next questions are:

What size wheels are on the girls frame?

What's the total weight going to be (bike, rider, engine)?

Are there any steep hills to contend with?

Are you going to at least install front and rear rim brakes?

Are you going to reinforce the fenders or remove them?

These questions need to be answered in order make the bike safe and determine what engine drive ratio should be used.

 

[Chainlube]

I never recommend to motorize any bike with a coaster brake, just looking for trouble. If you like a frame mount, a CG will work.

 

[WEEDHOPPER420]

OK, I'm here now to give you some actual useful information about the engine and transmission in question.

The engine produces 1.88 hp at 6500 rpm.

The transmission is 4.7\1 | a China girl has an internal reduction of 4.1\1. So very close to a China girl.

It has a 17t sprocket on it but can be changed to a smaller one.

The next questions are:

What size wheels are on the girls frame?

What's the total weight going to be (bike, rider, engine)?

Are there any steep hills to contend with?

Are you going to at least install front and rear rim brakes?

Are you going to reinforce the fenders or remove them?

These questions need to be answered in order make the bike safe and determine what engine drive ratio should be used.

24in wheels
Yes to rim breaks
No significant hills
Wieght im guessing around 200lbs total.
Removing the fenders

 

[Sidewinder Jerry]

24in wheels
Yes to rim breaks
No significant hills
Wieght im guessing around 200lbs total.
Removing the fenders

You can run a 10\48 for 20 mph top speed. A 10\44 will top out at 22 mph. Install the engine with the transmission. With an inexperienced rider don't go smaller than a 10t\44t.

Make sure she watches all 3 videos. Being a good MB'er starts with being a good cyclist first. Also let her know from a distance she looks like a pedal only bicycle approaching. People will pull out in front of you not realizing how fast you're going.