Red Line XR650R



3 replies to this topic
  • qcustom

Posted May 24, 2003 - 01:51 PM

#1

I'm not sure what red line is for this model of bike I saw a rev. limiter replacement box that changed it from like 8900rpm to 9200rpm or something like that what is the red line for a stock bike? I heard that sound tests are done at half of red line and they say that is like 3200 or 3500rpms so what is it?

  • Tarkus

Posted November 06, 2003 - 01:06 PM

#2

Greetings qcustom. I was wondering the same thing some time ago and located a value of 8200rpm for the stock rev. limit. I can't quite remember the source, a magazine article I believe. Have fun.

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  • qadsan

Posted November 06, 2003 - 02:45 PM

#3

3,250 RPM is what the Motorcycle Industry Council uses for the engine speed on the XR650R for sound testing.

http://www.mic.org/c...03FormFinal.pdf

I believe the rev limiter kicks in at ~8,200 RPM, but I'm not 100% sure. I've bounced off the rev limiter several times just to check it out, but I don't find extending the rev limit useful for me. An aftermarket rev limiter simply allows you to stay in a particular gear a little bit longer as the HP/torque continues to fall off.

Now if I was installing a new cam with a matching exhaust to and doing other changes to move the powerband up higher (like making my bike into a Motard racer), then extending the rev limit would be more useful to me, but then I'd have to consider things like heavy duty valve springs, etc, or else risk floating the valves if the engine RPM gets too high.

Take a look at any stock/uncorked XR650R dyno sheet and you'll see the torque falling off at ~5,500 RPM and the HP falling off at ~6,500 RPM if I remember correctly, which is well before the rev limiter kicks in. While you might gain one HP by extending the rev limit, it will only be gained at the very top RPM and well 'AFTER' the peak power has fallen off. It won't add anything to the positive side of the curve.

  • qcustom

Posted November 06, 2003 - 04:51 PM

#4

Thanks for you input. I wasn't going to install new rev. limiter. But I just wanted to know what it was I think they test exhaust noise test at 1/2 of redline.





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