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How does my bike "limit revs"

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So I have a burning question and i googled around and couldent find an answer. I own a 1990 Honda Xr250r. Does It have a rev limiter. If so does it have a electric or mechanical one. If so how does it work.      If my bike dosent have a rev limiter then what happens when i go full throttle, does it just hit valve float. And if it does, how long max can i hold it there. This question may sound stupid but i want to see what the bike tops out speed wise in each gear.

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All of the XR250s have analogue ignition systems, which do not have a rev limiter. The XR400 has a rev limiter because it has a more advanced digital (computer) ignition system. I replaced the stock analogue ignition system on my 98 XR250 with an IgniTech digital ignition system. The rev limit and ignition curve for the IgniTech ignition can be set by interfacing with a laptop computer. Hope this helps.

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   The XR does have a rev limiter function incorporated  into its CDI unit.   I think it is 10.5k rpm - but not sure.   I don't believe there is any real difference between the XR250 electronics and the xr400 electronics.   The advantage of an aftermarket CDI unit is to customize the advance curves/tables & to go above the rev limiter rpm (if desired). 

 

   The rev limit is electronically controlled - versus mechanical - Above the rev limit rpm - it doesn't generate spark... 

 

jeff

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   The XR does have a rev limiter function incorporated  into its CDI unit.   I think it is 10.5k rpm - but not sure.   I don't believe there is any real difference between the XR250 electronics and the xr400 electronics.   The advantage of an aftermarket CDI unit is to customize the advance curves/tables & to go above the rev limiter rpm (if desired). 

 

   The rev limit is electronically controlled - versus mechanical - Above the rev limit rpm - it doesn't generate spark... 

 

jeff

Thanks for the info, answered my question completely.

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Be careful with aftermaket cdi's some of them will damage your motor!!!   see my post on them.  

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   The XR does have a rev limiter function incorporated  into its CDI unit.   I think it is 10.5k rpm - but not sure.   I don't believe there is any real difference between the XR250 electronics and the xr400 electronics.   The advantage of an aftermarket CDI unit is to customize the advance curves/tables & to go above the rev limiter rpm (if desired). 

 

   The rev limit is electronically controlled - versus mechanical - Above the rev limit rpm - it doesn't generate spark... 

 

jeff

The owner of Vortex Ignitions told me a number of years ago that the XR250 has an analogue ignition system and that the XR400 has a digital ignition system. I think this person knows more about dirt bike ignition systems than most people. The reason that the XR400 ignition has a rev limiter is because the microprocessor can be programmed to cut out the ignition above a certain rpm.

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The 96+ XR250R does have a rev limit built into the CDI. You can get different CDI units that plug right in which change the rev limit. I am using a CDI unit made for a CRF230F on mine right now, which has a fairly low rev limit.

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