In Estonia there is no 250cc shifters (they use these in big tracks in other countries and their top speed is over 200km/h).
But we have 125cc three versions 1. without gears (rotax max) 2. with 2 gears (rotax dd2) 3. 6 gears (KZ2).
Also ProKart events there are also old soviet karts both 125cc, 1. 4 gears Minsk and 2. 6 gear CZ
(some use old soviet frames with old soviet tires and others have put these motors to modern kart frames.
If we compare my kart lap times then we have to take account that I have not raced with new tires (always used) so there goes at least 1s lap time
Then My driving skills are not very good and there goes another 2s lap time.
Last test we did in Põltsamaa "Kuningamäe" kart track with a driver who races KZ2 as pro. He got lap time 37,79 (in 7th lap with used green vega tires and there was no rubber in asphalt as there is in competitions). Also that was the first time he raced with that kart and I think he could driven better if the accelator wire would not have broken
He got to drive 4 minutes and 24 seconds only: https://youtu.be/rShP1MLI-p0
The same track track all time records are following:
Rotax max - 35.783
DD2 - 35.706
KZ2 - 34.297
Retro Minsk - 38.616
Retro CZ - 36.441
So 2 second slower than regular 125cc no gears and under 4s slower than KZ2 kart track record (you have to take account that record is from pro driver who knows how his kart acts and so one)
But if you take some Prokart Estonia competition then for example in kz2 races 4th place best time was 37,247 (about the same as we got)
DD2 winner best lap time was 36,343 so a little over 1s better.
So I think that when I finish moving to a new frame then a good driver with brand new tires can drive lap time close to track record