Depends what year you're talking about. I had a '97 809 that could out accelerate several previous years of 780's, but it was very close, if not equal most of the time. Although the 809 has a few more HP than the 780, along with it came the SC10 rear suspension with 10 inches of travel versus the 7 inches in the C7 that came with the 780 in '96 and before. I had heard that the SC10 robbed a little HP which I can believe, tending to make them more equal. On the trails, the SC10 in the F2000 chassis had the worst inside ski lift I've ever experienced. Because it sat lower, the C7 cornered flatter, but was worse over the bumps. The later CK3 chassis that they came out with in '98 was a huge improvement as it was better mated to the SC10. Now of course in the '98 CK3 you now had to contend with the new center outlet pipes which in the beginning didn't make very good HP because of thermal issues, but I have no first hand experience other than a few trail rides with CK3 Mach Z's, so I can't comment on drag racing. Bumps and compliance aside, I'd have to say that the '97 F2000 with the then-new SC10 was one of the worst handling sleds I've ever been on. It went like a raped ape in a straight line, but otherwise forget it. '97 was the last year of the F2000 and the first year of the 809; the only year they existed together. Hope this helps.
If you come across a 95-96 780, I would pick it up. The 780 has steel sleeves. Also, I don't believe they had Crank bearng problems. The first 809's had Crank bearing lubrication issues. Don't get me wrong, an 809 is a great motor, but the 780 ran just as good if not better. My buddy ran a 96 MachZ with a 780, and he never had one engine problem, that thing just ran all the time. Well he decided to sell it and get a 97 with the 809 and he has kicked himself ever since. The 780 did seem to be more tempermental to weather change, and not quite as smooth as the 809. All depends what you want to do and what kind of a deal you find.
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