BansheeHP (Bill from Driveline) has done lots of experimenting with his set up, he added boost ports, 70mm bores, dyno'd lots of pipes, etc.
Might be worth an email on here.
Good luck with the build and post pics of the setup
Sounds like your building something special. I had Cam do my engines, the last was a 421 and i had the same concerns. We went with 28s and a desert tank for mileage, its better on gas but i cant tell you by how much because its the only carbs ive ever used on it and its been riden sparingly. I just ordered 33s for it due to its hard to tune between pipes with these carbs.
I am currently building another 421 serval and i am not convinced i should. I kind of toying with the idea of a 347 or 358 cub or a 392 serval or driveline setup. A guy out here has a 392 DL set up by the guy at DL and its real impressive. The guys at Driveline would do my next build over anyone else if i was using their cylinders, they have done some experimenting and i thought the results were excellent.
Desert tank makes a big difference. What pipes are you running? Im asking because there is hp to find there, Shearers would make a nice difference on that engine.
What Claude said, porting is going to kill your gas mileage.
Yep, I’d be surprised if your stock stroke stock cylinder main jet is over 300. If you have fmf fattys they like a bigger pilot like a 30, but I would def buy 27.5 also. Set your slide mid way and adjust from there.
report back
100% depends on where and how you ride. If your strictly trails or track I’d use SLP. I had PCs on my 4 mil and they pulled real hard in the mid range. I wish I would have kept them. For a do everything pipe I like PCs a lot
Is your bottom end shot? If not true and weld your stock crank, they’re very stout.
the driveline top end for 800 is unbeatable. You would be at 392 cc with the stock crank.
What pipes and reeds do you have?
And you’ll need gaskets at the reed cages. While your doing that check your reeds, if they’re chipped or showing light through you’ll need new ones.
build or buy a leak down tester.
the jet sizes are written on the bottoms of the jets. So you have stock exhaust pipes?