Can someone help me I just put a new top end in and max speed is 35 mph then stutters can’t get anymore speed. Reeds were cleaned carbs and tank too. New spark plug cleaned points. Is there anything else I can do ? Please help thoughts ?, 

Your exhaust may be restricted. My GT80 and JT60 both create a lot of spooge from the exhaust. (oily gook) My JT exhaust was so loaded up with spooge that it actually felt heavy when you removed the pipe and held it in your hand. I burned it clean in a good hot bonfire and when I picked it out of the ashes the next morning it felt a few pounds lighter. Gave it a good wire brushing, fresh high temp paint and it ran noticeably better.

imgur.com/a/gRAuUKF

Ok I did notice when I had the exhaust off dark oil leak d out of it. Blew air down on it and drained out more… do you think it will help with power ?

Great chance of an improvement.

On a DT125 that I had many years ago, we had to cut the exhaust in half in order to clean it out. Once cleaned and welded back together, it ran fine.

Given our relatively close proximity to neighbours here in the UK, we aren't in the habit of putting exhausts on the bonfire! 

You can’t go wrong by giving it a try. I suggest doing it over an evening fire because as Al implied, it will smoke like crazy once it gets hot enough to burn off the accumulated crud inside that pipe.

However, I’m not sure how much more you will get out of it for top end speed. My little GT80 is no speed demon. I think my JT60 would give it a good run if they lined up for a race with equally sized riders. Plus I’m not so sure you should be testing top speed right off the bat if you just did a new top end. You might want to go easy and get thru a basic break-in period while the rings seat with the freshly bored/honed cylinder.