nklr dirt bike fuel injection

[nakedwaterskier]

'08 Suzuki Dirt Bikes RMZ450 The RMZ450 is the flagship of the Suzuki dirt bikes and the big news for '08 is the introduction of fuel injection. The system has been in place on the R450 quad for a couple of years but has now been fitted to the RMZ. The throttle response is much improved due to the fuel injection and should prove to be a lot less maintenance and tuning compared to a carburetor. There is a smaller capacity aluminium fuel tank fitted because the injection system is more fuel efficient, the tank also houses the electric fuel pump. The fuel injection does exactly what Suzuki was hoping for, as it improves the initial throttle response and helps to broaden the power smoothening it out throughout the low-to-mid range of the powerband. Since most four-strokes have a small lag when you initially crack the throttle, it almost took a little while to get used to the way the power was delivered on the bike, but once we did, like we said, it was impressive. Perhaps the biggest improvement in the engine department on this bike from last year is just that, as the actual power doesn't feel greater than other 450cc four-strokes, it's just delivered much better and without any hesitation or bog. EFI offers perfect `jetting', ultimate tuneability and better economy all good for MX in theory (see sidebar). But does it work in practice? Most of the tech is straight from Suzuki's well-proven road bike EFI box of tricks, made simpler and more robust for offroad. There is no battery. The system is powered by a high discharge, 18-pin magneto, which powers up the fuel pump and electrical system to drive the injector and brain. It also supplies feedback on crank position and speed, to optimise ignition and injection timing. Sensors in the airbox monitor air density and temperature, and feed information to the ECU. Airflow itself is dictated by monkeys' throttle hand, but is detected by the Throttle Position Sensor (TPS) that works with the air density information in the ECU to always deliver just the right amount of fuel. Altitude, hot, cold or muggy days, big handfuls or delicate throttle applications are effectively re-jetted, on a millisecond basis. The fuel pump keeps the injector nozzle primed at 294kPa and returns any overpressure fuel to a bladder surrounding the pump. The bladder is there so if you tip it over there's always fuel to suck until you pick the bike up. The factory has seen fit to add a 10-second shutdown override to prevent major engine damage if it's lying on its side revving its head off. Count out 10 seconds on your watch. It's a while isn't it? If you haven't got back to your bike in that time, stalling is the least of your problems. The throttle body is 43mm, which is large for a 450, but accounts for the restriction of the throttle butterfly. The throttle cable is connected to a progressive linkage, giving less movement at low throttle for more delicacy, and a quick open toward full throttle. This is a good thing EFI offers way cleaner jetting at low throttle openings than a carb ever can, and response can be a bit too bright. An example is the Aprilia RXV450 (yes, I know it's a V-Twin). On the `06 there was no throttle progression and it made life on slippery surfaces hell. The `07 had a progressive throttle and was a different bike. You can take care of idle speed with the choke knob, which turns in or out to adjust idle as well as going up or down when it's cold.