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airport4

Rev-limiter

6 posts in this topic

Can someone tell me if the XR650R has a built in rev-limiter and if so at what rpm does it start to do it's job? TIA

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Yes, there's a rev limiter to protect the valve train. I believe the rev limiter kicks in at ~8,200 RPM, but I'm not 100% sure. The rev limiter however won't protect from an over rev situation created through downshifting at too high of speed.

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Qadsan is right on. You can get a higher rev black box (CDI) off the XR400 which works just fine but from what I understand doesn't really add much usable power. There are occassions when I would have liked to have a little higher rev without shifting but not often enough to spend the money on the XR400 CDI.

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That is kind of comical, since if you follow the XR400 forum, you now and again see the XR250 CDI box come up as being mentioned as a "hop-up" igntion part.

In any case, I'd have to wonder if the initial advance and the location of the pulse pick up tab on the flywheel, and the advance curve are suitable for the 650R. In other words, you might be getting more changes than just the higher rev limiter setting.

To make matters more complicated, the 400 in North America got a "revised" CDI box in 1998, along with the leaner EPA jetting. The Euro spec bikes (which retained the fat jets) also retained the 96/97 ignition, which makes one think that the '98 box is slightly retarded to work with the leaner fuel delivery. I don't know of anyone who has actually used a tach and a variable offset timing light to compare the two boxes though, so the differences between the two revisions are unconfirmed educated guesses at the moment.

:thumbsup:

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Thanks for the info guys :awww:

I just wanted to make sure I wasn't over-reving my BRP thereby floating/bending the valves. It looks like its a non-issue if you can get the XR's only box and go to 9500 rpm :thumbsup: without changing valve springs.

:lol:

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