49cc or 80cc ?

[Hot Wheels]

Hi everybody, How can you tell from just looking at the motor if it's 49cc or 80cc. I bought a gas bike at a garage sale for 75.00 bucks. Thanks for the help !

[Dave31]

There is no way to tell what size motor you have just by looking at it.

[Cabinfever1977]

is there a metal plate on the left side of the engine with any info on it?
do you have a pic?

[Big Jim]

The 49cc has a round head and the 80cc has a square head. OK,I was wrong but it is 1 thing to go buy.

[mick29]

I found the 50cc has 6mm head barrel bolts and 70cc has 7-8 mm bolts but it could be differant on different makes thanks mick29

[Bikeguy Joe]

Not all the 50's have round heads. I have two 50's, a "65cc" and a couple of 70's here, and none are the same. One 50 has 8mm studs, the one 70 has 6mm studs.

The only way to tell is to measure the bore and stroke.

[stv1jzgte]

yeh i got 2 50's wid square heads 1 slant

[xlite]

Head nut size is not a reliable way to tell. Not necessary to take it apart. Diameter of cylinder between the fins works every time. Obvious once you think about it.

[stv1jzgte]

Originally Posted by xlite

Head nut size is not a reliable way to tell. Not necessary to take it apart. Diameter of cylinder between the fins works every time. Obvious once you think about it.

On that note. All 3 50cc barrels (all 40mm bore) i have are 57mm square.

Hot Wheels if your barrel measures more it aint a 50ish

[vincent713]

When you look at the head on the 49cc vs the 80cc, it's noticeably smaller.