Video will follow, just waiting for a couple of pushrods, Tom mentioned a few teething problems. Two of the rods jumped off the rockers at highish rpm. I have had a bit more clearance made in the pushrod tunnels now I know what happens when the engine gets hot.
But what I can say is that from about 2000 rpm it really starts to go, and by 6000 I am glad I have the rev limiter set at 7K, in 1st and 2nd it just feels like I can't change gear quick enough. In very good conditions I have hit the rev limiter in every gear, this is really amazing for an engine designed so long ago. In theory the engine should make power unto about 9K, but until I have the pushrod clearance issue sorted, I am staying clear.
Crankcase decompression is a problem, I have replaced the factory vent with a crank vent and I am in the process of modifying the later crankshaft vent to fit. At high rpm I am chuffing oil and smoking quite a lot.
My biggest problem at the moment is time, I have just had a revamp of the business and both children are at University now. I am typing this in Edinburgh where I am fixing some stuff for my son, then later tonight meeting my daughter at the airport, and off to Inverness to sort her out in the morning. Planning to hit the charity shops in Inverness big time tomorrow, her flat is unfurnished.
Waiting for those pushrods, Kevin.
Regarding 9k rpm, don't do it with those alloy con rods!
They will not last at those rpms, and they will also stretch, and pistons may hit the valves or heads, and when they finally do let go, it will be more than exciting! Absolutely, custom steel con rods will be required for getting anywhere near 9k rpm. Actually, the port size is set for about 8250 rpm in normally aspirated form(higher with supercharger or turbo), but it will be able to rev higher for a few hundred rpms more. With a 3.54" stroke in this sort of format, that's probably as high rpm as you really want to go unless you are racing for money or some kind of record. The piston speeds are dramatic at that rpm.
For the breathing problem at high rpm, get a KrankVent for that engine size. We have found nothing better than that. It's a bit pricey, but it works on all the racers like magic.
Edited to add:
I happen to know the holder of the 650cc pushrod gas land speed record in the East Coast Timing Association(ECTA) which runs the Ohio Mile, and his Triumph 650 race bike runs 128.2 mph, which is the current record for that class.
I calculate that with a 19T sprocket at 7000 rpm, your bike should be doing around 126 mph on the street!