A bit of a rare beast around these parts (although we have seen a couple); a Honda CB1000R. The stock fuelling, with the standard exhaust can fitted, is quite good to be honest. But unfortunately when you bin the stock can and add an aftermarket item the fuelling goes well awry…
It’s not bad at idle, or generally running around, it’s where you’re hanging onto the throttle but not opening it; like at fixed cruising speed with a negative throttle. 70mph is the danger zone here, on a trailing throttle, and let’s face it that’s the sort of speed (and use) that we do a lot, and this is where the engine runs dangerously short of fuel. The lambda sensor is trying to lean the mixture out all the time, and the lack of back pressure or catalyzer just makes it worse. Accelerating to this point is no problem, but once you get there, and stay there, it’s bad; sit on the motorway at 70-80mph on a steady throttle and you’re not doing the engine any favours at all.
The only solution at the moment is a Power Commander PC V and 02 Eliminator kit. We bolted both on, and focused the Dyno work around the mid-high rpm ranges and richened up the fuelling. After the work we didn’t have any major horsepower gains, but we really weren’t looking for any; instead the throttle response is much plusher and ‘fatter’ at high rpm/small throttle openings. The extra fuel really helps take the harshness out of the engine’s feel, and also ensures the life of the valve train and pistons…
Lose the standard can without sorting the fuelling and the engine in this CB1000R is headed for disaster...
