I think I might have that record. Taking a stock Cannondale speed engine and with my own porting . Boring out the throttle body and changing cam timing ,custom built dual exhaust out of the stock headpipes and mufflers. It went from the stock 37hp to 56.8hp using no aftermarket parts inside the engine. The only new parts were piston rings otherwise it was all the original stuff put back in. Thats nearly 20hp for about $30 and a weeks worth of work.

 

My head was once in the sand too... just not knowing.

But I can assure you, the Polaris 400 peaks the top of my list.
Engine is highly tunable, FOR CHEAP, and so is the belt drive/clutch.

Combining a 2 stroke with a PVT trans is like peanut butter and jelly.
Made for each other.
When properly tuned, the engine stays in the powerband, and the bike is really quick.


I'll just put it to you this way... my riding buddy brought out his pro-level build TRX450R (GNCC) on the last big ride I took my Sport 400 on. Full engine build, hand-built race exhaust, and 3-4 grand in suspension.... And he is a MUCH MORE practiced and polished rider than me.

He checked out in the really rough sections. Nothing stock is staying with that suspension. But I reeled him right back in every time, and stayed so close to him so long that when we stopped he asked me what kind of mix oil I was using....

Since he rides only 4 strokes, I had to ask "why?" and is reply was that mine stinks.


So my top 10 list is (having owned them most of them)

1- Polaris 400L
2- Quadzilla 500
3- TRX250R
4- 250 QuadRacer
5- Tecate 4
6- Polaris 250
7- Kawasaki 450R
8- Honda 450R
9- Suzuki R450
10- Yamaha 450

And yes, the Banshee is highly modifiable but did not make my top 10 list because of cost and complication combined.

The 400EX didn't make my list either... it would fall behind the Blasters and Z400 based machines.

Out of those 11, I have owned/own 7.