Question about Honda CR 250 R Motorcycles

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I bought an after market fatty pipe for my 85 cr250r. that bike has an exaust manifold with a butterfly valve that is part of the ATAC system that will not fit with the after market fatty pipe. My question is, does the fatty somehow have the same affect? Will the bike perform right without the ATAC valve on the exaust?

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  • jrod1031 Jun 08, 2009

    what would cause the bike to rev up really high and not stop. Throttle wasnt stuck, hit the kill switch, pulled plug wire and still would not stop. finally killed it by shutting the fule off.

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The ATAC valve you are talking about opens up when certaing RPM's are reached. ATAC Valve consists of a a ball bearing- ramp system connected to the water pump shaft.

If the ATAC valve is stuck wide open, it is faulty or it is removed you get this kind of problems.

Rev going up suddenly, no idling, etc.


This happens because running at low RPM the expansion chamber doesn't have the right volume and it won't work as it should.

Remove the ATAC valve and try cleaning it, ensuring that it opens and close, or have it replaced.

Do not forget to leave feedback.

Many thanks.

G.

Posted on Jun 08, 2009

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The butterfly is to help with low end power,the aftermarket pipe you have is mainly for upper rpm power,it will work just fine,but you may notice a loss of lower rpm power.

Posted on May 31, 2009

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