Call us naive, but we thought that having a full race system that doesn’t leak would sort out the fueling issues. Not so. A quick blast around the car park told us it was running even worse, it just wouldn’t pull at all, it would rev out ok at a standstill, but under load it had nothing.
We suspected the that the current jetting and air-box setup just wasn’t suitable for this exhaust, we’d have to get it run on a dyno to see what was going on. A call to the helpful guys at RB Racing in Caringbah answered our questions. NC30s should run either the stock air-box, or none at all, anything in between will cause problems, and ours was in between, it had the top cut off and a very thin race filter. We needed professional help with this so we handed the bike to RB and asked them to tune it. They removed the air-box and fitted an HRC air-tray, basically turns the whole area under the tank into a giant air-box, and it’s run with no air filter.
They upped the main jets from 138 to 160 (they are 118 as standard) and fitted an additional oil catch tank (necessary when you remove the air-box). This is the result:
A nice healthy clean 60hp. Very respectable for a NC30. The next outing at Eastern Creek the VFR was a revelation, it pulled well from low down (for a 400) and had a nice spread of power. There is a slight flat spot around 5k but you only really notice it when you pull out of the pits, the revs never drop below that on the track. On a road bike it might annoy you but it’s no problem on a race bike. Due to our RGV bike breaking down early in the day (see here) I had to move to a faster group so we could share the VFR. It held its own pretty well and considering it did double sessions all day showed no ill effects.