Will an 80cc motor handle my weight?

T

travisatwork01

New Member
Hi everyone, I just signed up today but over the last few weeks, I have been trying to gather all the information I can about building one of these cool bikes.

Being the neurotic I am, I decided to go to the Louisiana State Police HQ with a photo of what I want to build because I could not get a straight answer about what is legal. It seems that in Louisiana, anything that rides on the street has to be street legal, be registered at the DMV, have a VIN number, and insurance. It was funny that the photo I displayed to the state troopers showed two bikes parted in front of the state capital building and they were not street legal. lol

With all the behind me, the thought of my heavy body riding a 50cc motor did not sound to appealing, so if I’m going to have to make it street legal, I would like to have a 80cc motor. I weigh about 240, so I do not want to go thru all the red tape and find out that I get about 15 miles per hour.

Will an 80cc motor handle my weight?

Also, I want to buy an American motor. Do you know of any vendors that provide a good motor selection?

Thanks,
Travis.
 
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You are not going to find an American made motor if you are planning on using one of the 50 or 66 cc 2 stroke motors. At your weight I would get the 66 cc motor, there isn't such a thing as an 80 cc, they just refer to them as 80.
I wouldn't be as concerned with the motor as I would getting a good strong bike frame, with some good wheels and tires.

John
 
Travis, Welcome, I Go Close To 300, You Just Get The Rear Sprocket To Compensate. It Will Not Be A Problem. Some La. Members May Advise You About The Legal Necessities , Good Luck, Enjoy. Ron . . .cvlt1
 
You will have no issues with the wieght but a good rear rim and tire is a must. The rear sprocket, along with the high speeds are hard on those rims.
 
Retmachinist said:
You are not going to find an American made motor if you are planning on using one of the 50 or 66 cc 2 stroke motors. At your weight I would get the 66 cc motor, there isn't such a thing as an 80 cc, they just refer to them as 80.
I wouldn't be as concerned with the motor as I would getting a good strong bike frame, with some good wheels and tires.

John
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Or is it an 80 cc motor that we are forced to call 66 here in America due to our forms of measurement ??
 
lowrider said:
Or is it an 80 cc motor that we are forced to call 66 here in America due to our forms of measurement ??
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Huh??? who are you kidding? :D Is that the new math they are teaching in schools these days?
Where there are no wrong answers?
It is very simple math......

However, the bore and stroke of an 80cc being 47x38mm only equals 66cc.

To figure displacement for this example: 47mm bore x 38mm stroke; we use a standard formula to figure an engine’s cc displacement; ( multiply 3.142 x radius of bore mm squared x stroke length mm divided by 1000. )

Bore diameter divided by 2 = 23.5 mm radius

To square radius multiply 23.5mm x 23.5mm = 552.25 radius mm squared

552.25mm x 3.142 = 1735.17mm

1735.17mm x 38mm = 65936 cubic milliliters;

To get cubic centimeter divide 65936 by 1000 = 65.936cc or round off to 66cc.

As a result we see there is no such thing as a 80cc:
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Forbisher said:
Huh??? who are you kidding? :D Is that the new math they are teaching in schools these days?
Where there are no wrong answers?
It is very simple math......
Click to expand...

What about the space in the head? I really dont know anything about it but its my understanding that there is space there not taken into account in the equation.
 
I weigh 200 and a 50cc china motor pulls me fine.
I agree that you should invest in a strong back wheel (from a tandem bike or industrial bike, or have a shop build one for you). It will help your tires and brakes last longer and save a lot of hassle down the road.
 
I weigh 190 and the 48cc pulls me along fine. At first I tried the 50 tooth sprocket but could only go about 20 ( and the motor was screamin). I run a 44 tooth now and cruise at 25mph.
 
lowrider said:
What about the space in the head? I really dont know anything about it but its my understanding that there is space there not taken into account in the equation.
Click to expand...

yes, but adding those numbers into the engine size figure is incorrect... the formula is BORE X BORE X STROKE X .7853982 .. adding the extra cc from the cylinder head is incorrect as the head space in the engine is the combustion chamber and has nothing to do with the engine size.. they do that on the china engines specifically to make them sound bigger than they are...
could even take it a little farther.... if you had an engine that the pistions were in the hole say .025 instead of being at 0 deck, that would equate to about 3cc ( bore size effects this ) that would also become part of the combustion chamber, and then if you were to add a .045 compressed head gasket, that would add another 7cc to the combustion chamber.. so if it was say a 100cc engine, by figuring it the way the china's are advertised figured, it would be 110cc, because of a thick head gasket and a pistion that doesn't come to 0 deck.... but it doesn't work that way
 
To get back on topic, yes the "80"cc engine will pull your weight, with a 44T and using a little leg power for hills.

There are no current 2 stroke in frame made in America engines as of this date.
 
I have a 47cc that pulls me, and I weigh 200.
I just had a well used 80 out for a spin and it pulled the hills here with half throttle.
44T Stock "80"cc
 
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