In short, probably not much good at all. Many Dyno services are nothing more than getting HP and torque. While this gives you something to talk about at the local watering hole, it won't help much getting the most out of your bike. Look for an eddy type Dyno that includes a fuel / air monitor and load control. The whole point to paying for a Dyno 'tune' is, at the very least, discovering how your bike is jetted or mapped. In my shop we offer several choices for Dyno runs. The customer can choose several levels of set-up and tuning. In most cases, bikes are less than ideally configured and usually the customer will elect to get it tuned on the spot, bring it back later or take it home to do the work himself and then bring it back to check his progress. We recently got a bike from a local dealer that was way down on power. It tested at only 38 HP for a GSX750 (Katana). The dealer couldn't find anything anything wrong or at least anything that could expain the pathetic performance. As soon as we raised the seat, we found an old rag stuck in the airbox inlet. What we really found hard to believe was that the owner had apparently been complaining about the problem to the dealer for two (2) years.
1 - 3 of 3 Posts
It'd be perfectly good if you just want to know what your bike really makes. Be careful, though: A lot of the guys you find at shows and races like to bang the bike against it's rev limiter - Technically that's supposed to be OK, but I view that as abuse and wouldn't like that done to my baby.
But, as Dave pointed out, in an of itself a single Dyno run doesn't do much for you besides provide Food for Discussion. You can "read" the chart and potentially pick out areas the fuelling could be improved, cause the traces will look a little rough. But that's about it. More informative is multiple runs performed by the same operator on the same day, trying different things. Run, mod, do another pull, compare, mod, pull, compare... If they have a 4 gas analyser, that makes it MUCH easier to tune because you get a readout of the mixture telling you which way to go and roughly how much. Of course, the Dyno shop will tell you all of that when you bring your bike in. The Pitch'll go something like "Hmmm.... Not bad for an F4i... But look here, and here... See the roughness?? That says the fuelling's not right, so we know there's more power to be had in there. Could we interest you in a Power Commander and Full Tune??? etc etc etc..
Don't get mad at the coming pitch - I'm sure that they are perfectly capable of wringing more power out of your bike, and after all, they are trying to pay for a $30K~100K set of machinery and feed their families while they are at it. A $20 teaser run gets you into the shop, takes only a few minutes, keeps the machine/operator busy, and allows them the chance to sell you some stuff to get your baby performing it's best. If they keep good records, you should be able to look at other bikes of the same make/model with their mods listed and what they did. That's a HUGELY helpful tool you can use to decide what mods, for what money, are going to help you best. Keep in mind that any bike that SCREAMS near redline but is rough in the mids and at part throttle is going to be *very* hard to ride. So don't underestimate the power of a nice, wide, smooth curve. Even if you give away a couple ponies near redline. Remember that the earlier/smoother you can get back on the throttle mid-corner equals "free" yards/feet/10ths that your opponent will have a VERY hard time taking back. IOW - If your bike spits, you can't get back on the gas, and *you* will be the one giving away free distance to the other guys.
Most dynos are NOT calibrated, so you might get 114 on one machine, 105 on the next, 108 on another. There are also different types of machine - "Eddy Current" (FactoryPro) dynos use an electric motor instead of a weighted drum and typically read 15% lower than an inertia type (Dynojet 150~250). Arguably MUCH more accurate and they can do stuff like reliably repeat off/on throttle transitions and partial throttle settings. You can't do that stuff on an Inertia-type machine. E/C machines are also (obviously) much more expensive and therefore much less common. Temperature, Humidity, Tire Pressures, Chain Tension, and the like also affect the reading. So, the key to making sense of it all is consistency - You should find a qualified operator, and use him exclusively. That way you eliminate as much of the inherent error as possible.
Hope that helps!
Scott
1 - 3 of 3 Posts
