Does a 4 stroke Chinese need an upgrade hardware kit?

So your 2 stroke is already broken? CVT tranny to shift gears? And automatic clutch?
I want one to fit inside the bike frame, but it seems Harbor freights smallest is 99cc which is 1 foot by 1 by 1 foot.

Yes 30 minutes for break-in period, but after about 200 miles when the break in is finished, you can ride it for longer maybe a few hours - as they say and have done. Of course I plan on replacing some things and putting some mods on my 2 stroke. People report their chinese engines for thousands of miles.

I do not want to argue with you in this thread, but I've had both 2 stroke 47cc and 4 stroke 110cc engines. The 2 stroke did seem to overheat (I could smell the smoke) if running for long and the 4 stroke lasted me all day. But I want to try again with 2 stroke, because the 66cc might be different and better than the 47cc and should not have the same problems especially if I put a few mods in it. And engine running hot shouldn't be a problem since they can withstand it and not lose power.
I do not think either of us are right or wrong, it's probably because you had bad experience with 2 strokes. I did too, but do feel like I should try again even though I like 4 strokes better - but for bikes they are very costly and hard to fit inside the frame.

I wanted to know, how many teeth is your rear sprocket and how fast are you going with that sprocket?
I found a 4 stroke Chinese kit for a total of 300 with a 56tooth sprocket. If I put a 44 or 36 tooth sprocket will it be able to pull it? How fast? If so, and faster than 35-40mph then I assume it is more powerful and faster than the 2 stroke, or maybe the same. Since the 2 strokes are like 30 mph with a 44T I believe.
Which would have more horsepower, performance, and/ or speed - 2 stroke or 4 stroke with the same tooth sprocket? Or are they the same?

BGF ebay is selling some. And nice to know bikeberry selling, I might buy from him instead. 320 shipped - not bad. But I just noticed that these motors have less HP than the 2 stroke motors. Even though HP rating is false because they are NOT 5 hp, they are probably less than 2 strokes still.

I wanted to ask, do you guys ride/ or is it safe to ride 4 strokes at full throttle consistently for several minutes/ hours?

Another question came to mind: Which one accelerates better/faster? And which one goes faster (maximum speed)?