Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Good news Ted. You should leave the exhaust popping and banging as it is a) Badass and b) We'll know it's you arriving at Crich!
I once bought a 400four that needed a lot doing to get it going. After a week of fettling, it was time to test it. The battery wasn't up to much in the way of spinning the engine so a mate offered to assist. My road had bit of a downhill slope to it, which helped.Sitting astride the bike, in 2nd, clutch in, my mate pushing for all his worth, I let the clutch out and.....Huh? What?I hadn't refitted the chain 😀
What you have described above Ted is exactly how my 400/4 was after the engine rebuild. The engine felt heavy, tight and slow (in comparison to how it felt before the rebuild). It took a good 500 miles for things to start loosening off and even then, the performance was not staggering. But, all of a sudden, at about 1200 miles IIRC, the engine loosened off and she was a flying machine. Regular up and down the gearbox is a normal state of affairs for the 400/4 even when fully run in. At this stage, with your bike, regular gear changes are advisable. Just keep riding it and I'm sure it will perform better as you increase the mileage.If you read the last knocking of my rebuild thread, I explained there how and at what mileage it started loosening off.
31mpg is pretty bad Ted, you should get over 50mpg on a 400.