An Aprilia with Vision specs.

[jefferson]

Always liked Supermoto and watched it on tv back when the ama was running the show. Even went out to Colorado and watched one of the races out there. Jeff Ward really impressed as did all the other riders. The Aprilia came out around that time that I saw run in Europe, but was outlawed here and I really like the thing as there was a 450 and 550 version. It was the prettiest of all the bikes running and is still a very good looking and running bike today. My nephew got a KTM 690 Supermoto R and it got me to watching videos and then alot of SXV550 stuff. I looked up the specs and was surprised to see  the bore and stroke is the same between the Vision and the Aprilia. V angle is wider on the Aprilia at 77 degrees. Horsepower is not that much different considering the much newer design with higher compression and EFI and of course weight. My racebike dynod at 57.5 so with frictional losses it should be right there with it. I think the claimed horsepower was 70 and I have seen several figures for the Aprilia and they were all right around there. Yamaha was a bit ahead of the curve with the Vision.

[VisionMeister]

I noticed the bore and stroke match a long time ago and my thought was that fuel injection had cured all the ills of an aggressive cam timing with lots of valve overlap causing a carbureted motor to suffer with the back pulses that Yamaha tried to overcome with YICS. I wonder if transplanting can be done? Fuel injected Vision? Someone can figure it out.
Service levels were very high and frequent on the Aprilia. One guy used to run Hwy 49 between Coulterville and Mariposa like a gunslinger looking for sport bikes to embarrass.