The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: kurren on August 31, 2007, 05:19:33 PM
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In my journey for a cafe racer transformation of my R65 I saw quite a few bikes modification running without crossover.
My question is: what are the benefits (if there are) of running without crossover? Is it counter productive? Are there any dos/donts I have to follow to get rid of the crossovers (front/back).
While the no crossover look it's with few doubts more cafe racer, I won't sacrifice any reliability or performance.
As always, thanks for your attention, and help.
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I believe the reason for the crossover pipes was to improve mid-range performance, now whether you would notice it or not if you removed them, I'm not sure.
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Quite often there can be a bit of a dip in the torque curve as the HP starts to get it
its act together (and it can sometimes have a bit of a dip or flat spot too). The
theory of the crossovers is to adjust the tuning so that it minimizes the flats spots/dips
that can occur in the middle RPM ranges. Different engine designs behave differently,and
the other factors like how restrictive the mufflers are, among other things, also play a part.
You may not notice much difference. In theory, the top end of the RPM range may benefit
slightly from removing them, but I bet that it wouldn't be very noticeable on these airheads.
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Alessandro,
My R 65 is rather prone to mid-range torque dips.
( I still have the original exhaust setup- one crossover type 1979)
I hear that other R 65 also suffer sometimes from a mid-range dip, and vibrations in that region.
(in my case) it could be cured by richening the mixture, by raising the carb needles.
Wiemer.