Real 80's?????

Is this the formula for figuring displacement????
BORE x BORE x STROKE x .7854 x # of cyl.`s
If so my motor came out to 55.62.....
 
stuartracing said:
Is this the formula for figuring displacement????
BORE x BORE x STROKE x .7854 x # of cyl.`s
If so my motor came out to 55.62.....
Click to expand...

Area = PI R Squared: measure the bore and divide by 2. multiply this number times itself or hit "X" squared on the calc if you have that function. Now multiply this number times PI. PI = 3.1417. This will give you the cross-sectional area of the cylinder.

Cylinder volume = Area X Stroke. This will give you the volume in cubic inches. then go here and convert to CC's

Online volume conversion

Jim
 
Ive Always Been Told On Bikes( Motor Cycles ) That A 125 Is Actually A 124 And 250-249 And Soo On...i Bought My Kit From Livefastmotors And He Clearly States On His Sight That None Of These (china Motors) Are Even Close To 80;s... He Says Theyre 70's... This Is Why I Purchased From Him , I Had A Feeling That They Were Over Rated On Cc;s And This Guy Seem To Have Done His Homework ( Considering He Is Selling Them)... So Yeah Without Meassuring Id Say Mine Is A 69/70..:) Im Not Digg'n' The False Advertisement Of The''80cc''.what A Bummer... So Lets Call Em 69 Ers....or 81's :)haha
 
Re: Put up or shut up....

Bikeguy Joe said:
If those of you with an "80" can remove the head, measure bore and stroke in mm and report it here along with the engine kits name, we will start a pool of info here.
Click to expand...

Well here is the real deal.

The diameter of the so called 80cc is 46.7mm (measured with a digital caliper acurate to 1/100 of a millimeter). http://pack127.net/images/cylinderdiameter.jpg

The depth of the cylinder with the piston at full depth is 40.00mm. http://pack127.net/images/cylinderdepth.jpg

Sorry the photos are a little blurry... Anyway...

The calculation is as follows:

Diameter = 46.7mm
Depth = 40.00mm

Radius = Diameter / 2
Radius = 46.7 / 2
Radius = 23.35

Area of a circle (cylinder) = Pi * Radius * Radius
Area of the cylinder = 3.141593 * 23.35 * 23.35
Area of the cylinder = 1712.867 square mm

Volume of a cylinder = Area of cylinder * Depth
Volume of the cylinder = 1712.867 * 40
Volume of the cylinder = 68514.68 cubic mm

1 cubic millimeter = 0.001 cubic centimeters

68514.68 cubic mm = 68.51468 cubic cm (or 69cc)

So there you have it. The so called advertised 80 cc engine is actually a 69cc engine.

scratg
 
In my opinion, wouldn't it be worth knowing how Chinese come
up with 80cc displacements. Displacements in China ranges from
from 48cc up to an interesting 80cc, in 10cc increments. It :-||makes
since to me.
 
Joe not to get away from bore and stroke,But for a number of years i had a chinese cook.I asked her if she knew how to make rice krispie treats,she nooded her head to say yes,so off i go.When i got home that night,low and behold on the counter a cookie sheet with a towel over it.I was so proud of har gong jue.I removed the towel to discover FROOT LOOP TREATS,we were out rice krispies.
 
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