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 !![scratg scratg scratg](https://motorbicycling.com/images/smilies/satg.gif)
![scratg scratg scratg](https://motorbicycling.com/images/smilies/satg.gif)
On that note. All 3 50cc barrels (all 40mm bore) i have are 57mm square.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.![]()
If you can tell the difference by looking at my engines which is a 50 and which is a 66cc by the size of the head, I will give you both of them.When you look at the head on the 49cc vs the 80cc, it's noticeably smaller.