500 Dyno Results Different on Different Years ?

B

BornYamaha

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For any of you that have been around dyno runs very much. Do you think these variations in results are just differences in individual sleds and the small jetting changes or do you think Yamaha was actually tweaking something along the way and not telling anybody. The peak hp #s are interesting, but I am more interested in the rpm which they are located. The "99" & "00" are fairly similar. 75 to 80 hp starts 6800rpms & peaks to around 90 hp at about 7800rpm. The "98" is only at about 62 hp by 6800rpm, but it peaks at least 250rpm higher at 8050. My point, & question is should the "98s" really be set up to run at a little higher rpm than the later years. I know all part #s & engine specs are listed the same. I am wondering If they were tweaking the cdi box or anything else back then. My "98" has always felt strong at a little higher in the rpms than most have stated and it definitely has no power on the low end when it falls off the pipe. My engine is stock.


http://www.m-performance.com/Grafik/Dynobilder/yamaha/yamaha500/xtc500-98/grafxtc500.jpg

http://www.m-performance.com/Grafik/Dynobilder/yamaha/yamaha500/venture500-99/grafventure500-99.jpg

http://www.m-performance.com/Grafik/Dynobilder/yamaha/yamaha500/vmax500-00/grafvmax500-00.jpg
 
Very interesting! That's a fair bit of difference at 6800 rpm.
I have a cdi box from a 99 vmax 500. Would be interesting to see what it does on my moms 98
 
I would like to have that info as well. If you try this please report back. It may be worth it to make an investment in a particular year swap out cdi. I am only guessing it could be the cdi since I can't see any other differences.
 
youd have to look back in the yamaha tech update books as I am not positive on this but I remember something about the headgaskets being changed on the twins and this was for the newer ones, which will make a fair bit of differance as the more compression will make more power sooner.
 
Even with changes to the 500, they were small changes. I would relate these dunno runs on different conditions, and different dyno's. After all the results are merely extrapolations of data. Do the charts show relative humidity, elevation, and temperature?
 
I agree that there can be differences, but these runs are done on the same dyno.
 
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