Hornet 2006 PC36, Can't Accelerate More Than 170kmh

[bellerose]

Hi guys, I was on a deep google dive and happened upon this forum, saw someone with similar problem, but the discussion is very old, so I'm posting a new one for myself just in case. (CbF600 won't pull under load)

I have a Honda Hornet 2006 (pc36), imported from Italy. The bike had probably sat for several years before being sold because the fuel tank had started rusting.
We changed it for a new one, did a carb clean, full maintenance (oil, chain + sprockets, air filter, etc.). Since it was my first bike, it took awhile to notice it was not running at it's full power. It turned out it did about 50% (later learned that the carb slide opens about 50% on full throttle).
So at this point, we've checked all electrical, tps sensor, coils, etc. Narrowed it down to the bike not getting good vacuum to open the diaphragm (which is in very good condition too). We tried with a softer spring, and there was a slight difference.
Does anyone have any direction what to look for? What might cause bad vacuum? Can a faulty PAIR system get in the way of the vacuum? We are at a total loss.
Other than this, the bike runs smoothly and sounds okay. Dies at about 160-70kmh. Any direction is appreciated :/

[stinkwheel]

Could it have been restricted for A2 licence compliance? Check for throttle stops or restrictions in the inlet rubbers.manifold (can be washers in the manifold, a drilled plate on the manifold or they did make OEM restricted inlet rubbers which are narrow down the middle).
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