If your getting 53mph out of the air cooled 386 with Big Bear gearing keep it and put it in the ATV hall of fame. Kodiaks 401s and Grizzly 420s are lucky to hit 50 with more power and taller gearing.
My 350 Big Bear sure screamed at 40 mph even my 500 only does 55 and the 660 grizzly we ride with does 60.

I like to see me do a 2 mph creep by passed a Big Bear down a open road.

We ride them down paved roads with cars telling us how fas ATVs go so our number are spot on ,do not trust those junk ATV and sled speedos.

 

I am only judging the mph by riding on a highway with traffic...we had an 09 grizz 700, 08 king quad 400, and my 08 air-cooled 386 cc low geared big bear and all three read the same on the speedo. I would agree that the quad/sled speedos may not be spot on, but for all three of them to read the same seems a bit ironic! Anyhow...I will go get my quad ready for the hall of fame. It is definitely worthy!!

 

You were keeping up because I was pushing you and the Grizzly was towing you! J/k We were definitely doing 50+ mph down RT 80 coming out of Gilbert. Sounds like you will be going a lot faster than that on your way into the HOF.