Excuse my inexperience here please. I have a totally stock 400EX. Can I just change the rev limiter without having to change anything else? If so, where would I notice the difference? I mean, would I have to be WOT to notice it? When I go to the dealer to buy the XR250 CDI, does it matter what year I tell them? Thanks in advance.

 

I stopped at the dealer the other day to price the CDI (XR250 2000) and it was $108. I think the dealer I go to is high, mainly because they have little competition. I am still wondering if it is just a bolt on change without needing any other modifications on the 400EX. Thanks for any info.

 

I don't run a 400EX, but have have worked on several. My opinion on the matter is, if you don't plan on putting in at least a bigger cam, why waste the money on the rev box. The stock springs can take the revs. However the stock cam is not designed to allow the motor to breath efficiently at 10500rpm. All you are doing is floating the valves, which can cause serious damage such as, bent valves, broken pistons,and worn cams. If you plan on putting in the box, you might as well take full advantage of it and get a cam. Unfortunately the cams are hard to come by and WB is backordered. When we do the 440 kits we try to get the owner to go with the high comp. piston, cam, and CDI, then they go pretty good. Later
eric

 

I aggree with Veeshan....also the horsepower drops "like a bad habbit" after 8500 rpm's. Unless you do some engine mods instead of aftermarket bolt-ons, the cdi box wont do you any good in the seat of your pants. The dyno's prove this red-handed. If you really got the greed for power....install the 440 kit and put your money into something worthwhile.

 

Thanks all, that's what I was looking for.