Ok how much off

Examples are My Hawk stock speedometer was 5-6 mph off. I replaced it with a more accurate digital speedometer. My X22R was 10 mph off and bought a speedometer calibrator to get it dead on accurate.

Are you still running the stock exhaust and carburetor with stock jets? If you haven't tuned it or installed a free flowing exhaust the performance will be on the low end.

Yes it’s got stock exhaust and an stock carb parts

Your average chinabike, regardless of who made it or what it is, is usually off about 4 to 6mph at highway speeds. Aka, if it says 60, its really doing 55ish

So technically doing 45mph instead of 50mph

What jets would you recommend??

Would drilling holes around the inside of the exhaust around the baffle make any difference in performance?

Thats the general rule, give or take a couple MPH maybe. At 50 indicated you might be doing 46 to 48. A GPS Speedo app on your phone can help you track the difference.

That depends on a lot of factors, but a good starting rule of thumb with most of these motors tends to be around a 105 main jet with no other mods at lower altitudes. Pilot jet depends on what style it has, but typically the most common sizes are 36,38, or 40. for a Keihin jet. It really helps to know your starting point to be able to make any suggestions.

Generally that can help improve flow a bit. Removing the catalysts from these bikes if often even more effective in terms of opening up their breathing.

O ok ty sir

How would I remove the baffle it’s got rivets on the outside and if so do the holes were the rivets were need to be covered ?

What’s the size of the rear sprocket on the Df250rtf villain chopper???

I’m wanting to downgrade for more top end speed