Hi @matt0084,
77MPH sounds pretty decent to me! My DTRE certainly doesn't reach those speeds anymore and I've just about tuned everything on it. I swear when I got the bike bone stock it did 80+ and went off the clocks. But alas, I suspect I've put on weight and so has the bike and that's what I'm left with.
I'm not sure what restrictions Italian models would have had, are they the same as the UK models.
Of course, making sure the YPVS is working is going to be your first port of call. The way I check this to rule out other possibilities, is to align the valve with the exhaust port so that it is flush and then disconnect the powervalve system.
Go and take your bike for a ride. Without the valve you'll notice it's lost all bottom end, but after 6K RPM you should feel the bike come alive and scream to the red line in every gear. This is going to be what your bike would be like if the valve was working (minus the bottom end loses).
If your bike is like this, then you know the issue lies with your valve timing (you've indicated it's reversed so unreverse it).
If your bike is still sluggish and slow, then your problem lies elsewhere.
It's a misnomer about the second bottle on the boot. Please restore this bottle to the air boot, it is not a restriction.
On the DTR engine there is free performance to be gained by flowing the crankcases. If you remove the reed block and look down the inlet port, you will see that the spigots on the bttom of the barrels protrude into the ports. There is around 12mm to be removed from the spigots.
Also, port matching the bottom end to the cylinder is very important. If the crankcase transfers don't match the barrel transfers then you're just dropping performance on the floor.
Sadly both of these free performance improvements require you to dismantle the engine, but worth bearing in mind next time the engine is stripped.
