My airbox is completely stock. I am running ice radar runs this weekend on Feb 3. I have 550 sheet metal screws in each tire. I'll let you no what I get with a radar gun.

 

Actually, a GPS is about the most accurate way that you can measure your speed and the beauty is that the accuracy comes from the sattelites, not the receiver, so it doesn't matter if you have a $99 GPS or a $700 one, the accuracy is the same. The only thing more accurate is radar, and that has it's limitations, like calibration errors. Comparing a GPS to a speedometer I'd trust the GPS every time.

 

Maybe none of you are wrong. If the same person was to ride 10 stock Raptors with everything the same (identical break-in time on them, same amount of fuel from the same pump, on the same road at virtually the same time so that conditions are identical, with the same parts such as tires at the same inflation, all bikes tuned perfectly, same warm-up time etc.) he would likely post different speeds on several of them. Engines vary in power output-they're not perfect. The brakes could drag more on one machine than another. The wheel bearings, oil viscosity and so on can all affect top speed, let alone the fact that he wouldn't shift at exactly the same rpm every time. No two machines are exactly alike, and the conditions vary a lot more when different aged machines from all over North America with different riders are being compared. As a mechanic, I've seen this argument many times. There are just too many factors to consider. I know this is long-winded, but I'm just trying to make a point. If they are within a few miles per hour of one another at over 70 mph., thats good!

 

BirdofPrey,

I totally agree with you. I have an FMF headpipe, a Pro Circuit t4 silencer, a Pro Design Filter, a Dynojet Kit, and a Garmin Etrex GPS. I got 74.2 mph out of it in 4th gear with a 14t drive sprocket. It actually slowed in 5th to 73.9, but that, I'm sure, was due to distance. I started and stopped in the same half mile flat area. Seems that most of my additional power from mods has only added to the bottom end, where I didn't really want it, but it's still feels more impressive. I've seen the same figures you mentioned and I think it's pretty coincidental that our results or so close. I'm going to try without the airbox lid in 5th and see if it'll pick up. If not, I'll work my way back down through the sprockets; 13t next, then back to a 12t if no change. If I can't get more speed in a quarter mile, then there's no point in doing it just to "say" it's faster, hell it's unusable! I'll let ya know the results! Oh, and if the GPS is wrong, so is my '99 Silverado; They maintained 1 mph difference @ 30, 40, and 50mph. Ride Out!

 

jscyoung, you made a very good point. I think what everyone is looking for is kind of the average that can be claimed from the bike. Something to compare the bike to other bikes and to your own ect..

 

Regarding GPS variances, its important to remember that those satellites are owned by the government. the signals they shoot back to earth and picked up by the recievers have an included SA/A-S signal strand. SA/S-P to the non military crowd is Selective Availibility/Anti-Spoofing so the enemy can't recieve highly accurate positions and the comsec that only top secret clearances can get. Those signals make the positions off by just meters (15-20 if I remember right). since the satellites actually send time to the recievers, its the recievers job to calculate by way of 3D triangulation your position. Basically, what I'm trying to point out is, the government sends out signals that are known to be a tad bit off. If you want precision navigation/speed calculation, many manufacturers have an accessory you can add to your GPS. Its called a DGPS and uses a land based correction signal broadcasted by the Coast Guard. Last I heard, its accurate down to 4-6 feet, rather than the 49 feet claimed by the GPS makers.

Enough rambling, its time to ride.

 

rbowman, you WERE right about the selective availability from U.S. satelites, but I was told that they dropped this about the spring of 2000. My GPS seems to be considerably more accurate now.

 

The selective availability is still in effect, according to our commo specialists. I heard the same rumor. Its quite conceivable they may have changed the way its implemented though. Catch ya all on the flip side.

 

Hunter32, You mentioned 2 supposedly most accurate ways of judging speed. First off the GPS is not all that accurate.. It is highly flawed compareds to the radar gun type method, Second is that you forgot the only TRUE way to determine speed. DISTANCE \ TIME!! If everyone is so interested in the top speed, why dont you just use the old method of a stop watch and a measured distance (the distance has to start AFTER the bike has reached top speed) For those of you who are into exact measurements setup 2 laser trip lines exactly 500 ft apart and hook em up to a timer.. Then get some crazy assed light person to go as fast as they absolutly can and go through the "speed trap" Do a little math and wala, You have now officially clocked the speed of a crazy ape attached to a 4-wheeled dinosaur!!

P.S. You can then also use the data to figure out the exact horsepower of the machine too!

 

rbowman, thats really interesting. I was sure my GPS was more accurate. If you can find out if they have at least changed the amount of error, I'd sure like to know. I remember some guys at work discussing the attempt to get the Clinton administration to drop the selective availablity (because it was useless because of "averaging" and DGPS etc.) about a year ago. I can't remember who told me later that the government had actually dropped it, so I can't ask where they got the information. Probably just a rumor. Thanks for the info..