GY6 49cc needs rebuild, HOW BIG CAN I GO By billwgol (Read 3,146 times)

[billwgol]

GY6 49cc needs rebuild. Can I up grade this engine to a 125 or even 150 by installing crank cylinder and head of 125 or 150??

The 100cc big bore kits only actually give you about 65 total cc. I would like to get as much engine as I can on the rebuild....even 100cc would work..

Thanks for any and all tech support you all can help with...

[ctpgs]

the 100cc kits i believe are 80cc kits 50mm don't think that you can put a 125 or 150 kit on it, you could probably buy an complete engine and hook it up with some work, if you go to 80cc kit might want to change the crank at the same time

[billwgol]

The bore is 5 cm × 3.14 × stroke 4.14 cm = 64.998 cc. if you came up with anything different let me know how... far cry from the 100 cc it's advertised to be...

[scooterbob]

I installed 100 cc kit from Scorpion performance. It includes piston , cylinder, complete head, Camshaft, rocker arms . carburetor, exhaust, variator weights, complete set of gaskets. new oil pump and more $179.00 . With shipping. Easy install. There's a video on You tube that you can down load. Its an excellent video. installing a 100 cc big bore kit

[billwgol]

Scooterbob, 100cc big bore kits, do not totally up to100cc's you end up with a total of about 65cc do the math bore and stroke does not equal 100 cc's I'm looking for something bigger I probably have to change crank possibly do some work on the engine case that's fine I can do all that. I don't know the cranks specs will the 100 cc crank fit into my 49cc case

[scooterbob]

I Don't know about the math. I do know that the piston I put in was twice as big as the 50 cc piston. You have to take in account the high performance cam. and rocker arm, head, valves ,carburetor, exhaust intake and variator weights. This all adds ups to be a scooter that scoots as fast as I want it to. Try it you may like it. Your friend scooterbob round pants. Over and out.

[ctpgs]

it would be 81.322cc bore is 50mm stroke is 41.4mm
www.nightrider.com/biketech/calc_displacement.htm

there is no true 100cc kit that i have seen all are around 80cc
i have seen one on monstergy6 that is an 85cc kit

[billwgol]

ctpgs..I think people on here or maybe I need to go back to grade school math.. the scooters are measured in cubic centimeters.. not cubic millimeters... 50 mm is equal to 5 centimeters.. 41.4 mm is equal to 4.14 centimeters... if that comes out to more than 65 cc, you show me the math the brings it up to 80 cc or more..

[ctpgs]

i just clicked on the link and entered the numbers in millimeters and it provided the answer i did not do it myself ,if you do want the math here it is
Calculate cylinder displacement from bore and stroke in millimeters. Divide the bore by two to get the cylinder's radius, then multiply the radius by itself. Multiply that figure by pi (3.141), and the resultant figure by the engine's stroke in millimeters; divide by 1,000 to get the cylinder's displacement in cubic centimeters. Using the example engine from Step 1, we divide 50 by 2 (equals 25), then multiply that by itself (25 x 25 = 625), then we multiply 625 by 3.141 (equals 1963.125), multiply again by the 41.4-mm stroke (equals 81273.375) and divide by 1,000 to yield 81.273375 cc per cylinder. slightly lower than the calculator i entered it into, 81cc none the less still , but any 50mm piston kits is usually listed as 80cc some like to list as a 100cc kit don't know why guess it sounds better scrappy dog is one lists the 72cc kits as 80cc and the 100cc kit in their description they say it s 83cc that 100cc guess gets attention.
here is an 80cc kit is marked in description 81.3cc
www.racingplanetusa.com/cylinder-airsal-sport-80cc-139qmb-50cc-kymco-4stroke-p-138953-1.html?cPath=27987_27989_27995&sessID=4edff5a163fe7ba9ebafc35041a3cb08

[billwgol]

To calculate volume you take the surface area multiply it by the height.... the surface area of a 5 centimeter piston... 5 cm x 3.14 = 15.7 sq. cm × the heights or in this case, stroke 4.14 centimeters = 64.998 cubic centimeters... that's how you can calculate volume of a cylinder

[ctpgs]

www.ehow.com/how_8194417_calculate-cubic-centimeters-cylinder.html
according to your formula a 250cc Kawasaki ninja comes to be 80cc
bore s 62mm or 6.2 cm stroke is 41.2mm or 4.12cm
6.2x3.14x4.12=80.20

[billwgol]

guys let's take a 350 Chevy.... 4 inch bore... 3.48 inch stroke... 4×3.14× 3.48×8=349.6704.... 350 chevy.... that's how you calculate volume

[ctpgs]

if you convert to cc it does not work 4 inches = 10.17cm 3.48 inches equal 7.9756cm 349 cubic inches = 5719cc
10.17x3.14x7.9756x8 =2037.529=124.33 cubic inches

[frmrwiseguy]

Sept 5, 2013 9:19:40 GMT -6 billwgol said:

guys let's take a 350 Chevy.... 4 inch bore... 3.48 inch stroke... 4×3.14× 3.48×8=349.6704.... 350 chevy.... that's how you calculate volume

LOL! another Issing match!
yup as I Provided .7854XBoreXBoreXStrokeX# of cylinders.
My SBC is 4.040 Bore with a 3.750 stroke= 385ci.
6. inch rods but that has no factor in Displacement.
Good Day!

I used to love back in the day a kid with a 80cc bored to +.020 called it a 100cc. Hey 80+20 = 100 right. LMAO!!

[billwgol]

If I measure something is 50 millimeters across is that not the same as 5 centimeters... you can play all kinds of games with numbers but 50 millimeters is going to be the same distance 5 centimeters all day long... 50 × 50 × 50 millimeters cube is going to be the same size as a 5 × 5 × 5 centimeter cube