Search online for go kart speed calculators. Then just plug in the variables.
With 6" wheels you have two common tire sizes 4.10 x 3.50 and 5.30 x 4.50.
The smaller wheels typically are 12-13 inches diameter and the larger are 14-16 inches diameter.
Here's an example of the smaller wheels...
Saw this on Craigslist tonight...
Ad price $15,000 but then in the body of the ad...
$1,500,000!!!! At least he said Or Best Offer
I got a kick out of the guy saying serious collectors only when there are clearly aftermarket parts on the bike. Fenders, brake lever and cable, no front...
I took some measurements against the Arctic Cat. The rake is within a few degrees, the Bird actually has more rake.
The wheelbase of the Bird is 1 1/2" longer which was a surprise, so extending the wheel base is out.
I don't know how to measure trail...
The only other thing I can see is...
Doing some more work on the little Bird. I bought new Astro wheels and some CST tires. We also straightened the forks again (neighbor kid ran into the fence) and replaced the front springs with longer 4" ones.
I bought the more rounded CST tire thinking it would make it more stable. I...
This is where I would check as well. Make sure your kill switch wiring is not grounding out on metal somewhere.
Edit - if it runs on spray, it's a fuel issue.
Perhaps there is blockage in the needle & seat, float is stuck, or the jet is plugged.
We were fine until that little pocket bike of your buddies showed up with the straight piped 79cc.
Just walk down 1 block & hop on the trail down by the river. The SSSCat & Bird are quiet enough behind the hills.
The old guy isn't going to get less cranky & he has more time on his...
Well, I couldn't take it anymore.
I tore it down & checked the valve lash. It was .002 intake & .006 exhaust.
I lapped the valves & ground them down to .008 intake & .011 exhaust.
Also I set the coil to flywheel to .012
Slapped it back together & boom the power is back!