Is there really an 80cc?


New Member
Local time
12:41 PM
Feb 12, 2008
I have heard conflicting stories about these 80cc engines. Some people say that there is no such thing as an 80cc engine, but many people are advertising them, such as Spooky Tooth, Boygofast, Kings Motor Bikes, and many other online sellers. Is this just a mistake? Or is there really an 80cc engine on the market?
there is really NOT an 80cc Happy-Time. unless it's just come out and noone's yet aware. matter of fact, i recently measured an engine for a seller (not a review) who received a sample from a factory claiming to have extended the stroke for a bigger overall displacement. the factory called it an "F80"...i knew by looking it wasn't so, but i measured...47mm bore by 40mm stroke...another lie in a market plagued by lies.

"buyer beware"...better still, "buyer be educated" read read the forums :)
read read read the forums
...especially the reviews.

the best i can do at this point is repeat our best advice...almost everything one could want to know about the happy-time is here.
Also remember that with a 44 tooth sprocket that these kits usually come with unless you're on a bike with a 50 inch rear rim you better forget about looking at 40 mph on a 26 inch wheel. 20 is more realistic. 25 is "she's ready to blow Scotty".

I'm not clear on why some 80cc engines are described as "66/80cc." Is this truly an 80cc engine? What does the "66" mean?

Hey Chris...

It would seem that in real terms an 80cc engine is in actuality a 66cc engine, just labeled as such!

Over time, on Ebay, I have seen 48cc, 49cc, 55cc, 66cc, 70cc, and 80cc... to my knowledge, correct me if I am wrong, the HT engine only comes in two different displacements I believe

I guess to make you think you are getting a larger engine
Just like with any motorcycle engine, they tend to round off the c.c. size.
like a yamaha 100 c.c. engine may actually only be a 98 c.c.'s.
My guess is that some sellers list them as 80 c.c.'s to get the buyer to think they are getting a bigger engine than the others that are offered as 66 c.c.'s.
in reality all of these engines are 66 c.c.'s except for the 50 c.c., which is actually a 48 c.c.
Thanks for the info, guys.

Geez: 66 to 80cc?! That's really rounding it up. What about 70?

This reminds me of the .38 caliber pistol: The real size is .357 caliber, but they rounded it up to .38 in name. But when manuafacturers started making heftier pistols that could handle a "magnum" round, they reverted to the true size of .357, and the famous ".357 Magnum" was born. Oh well; at least I can use cheap, .38 Special rounds in my revolver when I don't feel like loading it with expensive, high-grain .357 Magnum hollow points!
No such thing as an 80cc "happy time"/china made bike engine. Only buy the "hype" if the price is good. There are differences in engines from China, though. Some have more power, some are more reliable, and some are smoother and some will vibrate enough to numb your hands after 5 minutes of riding. Its almost a crapshoot because production quality with same factory can be very variable.
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