See them racing at every Hillclimb. They are wicked power and loud. They all have custom exhaust w/o silencers, They are usually on 250 chasis. Alot can happen to them. Parts availability is big problem, three carbs to jet, three coils, you get the idea. I've seen them lose a cylinder and couldn't tell. It sounded the same to me, but the riders are very intune with their bikes on these beasts. The motor is pretty wide also. Similar to riding a horse. Also the clutches that I have pulled on, are very hard to pull in. Don't know if that was an H2 issue or rider set-up deal.
They are rockets, though, and literally rip nobbs off of Terra flex cut tires. When those bikes pull out of the hole, the tire spinning and hooking up noise is very noticeable. They are 750's stock and this buddy of mine has one bored out to 800cc for open class. I'll see if I can come up with pics.