xr650r will not hit rev limiter in 5th

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xr650r will not hit rev limiter in 5th

Post  xr-kid on Fri May 23, 2014 9:42 am

Hi All

Please could anyone help, I have a 2001 supermoto xr650r with a full power core 4 pipe, 175 main jet, 68s jet, B53E needle on 3rd clip, k&n filter, air box mod but not vented the side panel. Gearing is 14 front and 42 rear. Mixture is 2 turns out.

In every gear but 5th it will rev out then in 5th it will only rev to 6500 rpm, why does it need more air?

Thanks in advance for any advice.

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Re: xr650r will not hit rev limiter in 5th

Post  Mauser on Fri May 23, 2014 10:07 am

You might have reached the peak power of the engine in 5th, not every engine will rev out in all gears, there is a point where your motor cannot provide enough power to make the bike go any faster and as such she won't rev out....bit like stick a 15 front and a megga small rear the gearing will mean it's impossible for the bike to ever achieve max rev's with that set-up.....if that makes sense. Easy way to prove the point is to reduce the gearing, try a smaller front or larger rear and see if the bike rev's higher....I am sure it will.

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Re: xr650r will not hit rev limiter in 5th

Post  Zoro on Fri May 23, 2014 12:53 pm

I agree with Mauser, put a 48 on the rear and that thing will hit the limiter in 5th for sure. You may have issues keeping the front on the ground on your way to 5th though.

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Re: xr650r will not hit rev limiter in 5th

Post  AURORA on Fri May 23, 2014 3:24 pm

How much time on the motor?
Compression readings?
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Re: xr650r will not hit rev limiter in 5th

Post  xr-kid on Fri May 23, 2014 3:57 pm

Not gone as far as compression readings. Not sure what you mean by time. Bike top speed is 91 mph, yet friends hitting about 105 mph with same gearing as mine. Would it make much difference if I drill the side panel.

Cheers guys.
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Re: xr650r will not hit rev limiter in 5th

Post  AURORA on Sat May 24, 2014 3:01 am

Remove sparkplug.
Attach compression tester.
Get a cold and warm engine compression reading.
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Re: xr650r will not hit rev limiter in 5th

Post  AURORA on Tue May 27, 2014 2:51 pm

Open up you airbox side panel!
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Re: xr650r will not hit rev limiter in 5th

Post  AURORA on Tue May 27, 2014 2:53 pm

How many hours are on your motor?
Are you the first, second or third owner?
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Re: xr650r will not hit rev limiter in 5th

Post  AURORA on Tue May 27, 2014 2:54 pm

Did you adjust the valves?
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Re: xr650r will not hit rev limiter in 5th

Post  Mad Frosty on Tue May 27, 2014 7:53 pm

common possible issues -
loss of compression
incorrectly jetted carburettor
dirty airfilter
incorrectly adjusted valves
damaged/faulty spark plug - unlikely .
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Re: xr650r will not hit rev limiter in 5th

Post  xr-kid on Tue May 27, 2014 9:12 pm

My side panel was not drilled, opened it up and fook me the beast is alive!
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