big bore

I think 904 is a bit silly for a first time build. Too many variables. The 810 build is common enough that we can help with experience. Nobody's ever done a 904 before to my knowledge, except for that one guy.

You'll definitely need a ported head with bigger valves and aftermarket cams to take advantage of all that capacity.

But if thats what you want, go for it. You'll need turbo con rods to go with those pistons too. They're a bit hard to come by but not impossible. I got a set for a good price this spring. We'll help as much as we can if thats what you want to do. Really depends on your budget. I figure for a proper build with those pistons you're talking $5-6000 including a new set of carbs. You can go to 810 on stock carbs, cams, head, and upgrade that stuff later. So its more about budget really.

The 750 is an inverted 4. The bike pictured, I sold because it had no title. I really wish I'd kept it because it was a 77 KZ1000A1, and MAN, was it ever fast......

What blocks are the same(or interchangable)? Will a 1000 bolt on the 750 frame without serious mods? Could I stroke the 750 using 1000 parts like the jugs and crank, or are they just different animals? I don't want to dump 5k into an engine build when I can buy a semi tired race bike off Chi-town craigslist for 3k or so.....lol.... There was one here in StL last year for $2800.00, but when my wife and and my mom found out how fast it was, they teamed up and said......OH, HE-ELLLLLLL NO!.......it was cool! Stretched, raked a little, billet wheels, msd two stage, 200mm rear, air shifter, the works. Backcut trans etc....... It was a 1085 from a 900 crank and I believe it was in a 1000 block. Shifted at 12000, rev limiter was set at 6800 out of the hole and 12500 redline.

12,5 is a little high on the rev limiter on my opinion i wouldnt want to rev my engine up that high for very long. If you want alot of speed and power maybe it might be cheaper to just get a 1000 anyway, and if you wanna drop alot of money in it then go for it, theres tons of stuff out there for them.

You can't interchange any parts from the 650/750 and the 900/1000. They are for sure different animals. If you want something good, just stick an 810 kit in your 750, some supporting mods, and you'll be good to go. That will only cost you a couple grand. Or just go out and buy a bike thats done anready if thats what you want.

That's probably going to be the most cost efficient, unless I find a nice "barn find" and maybe a sport bike with a blown motor or something...... Thanks for the input.