I have a '99 300EX with a K&N filter, DG RCM header/pipe. I'm hitting my rev limiter more now than before my mods. Does anyone have a modified cdi, how much was it, who does it, and is it a worthwhile mod? Thanks in advance, Mike.

 

There's two schools of thought about a modified CDI for the 300EX.

One is, this is a great mod, and for about $65 gives you another 2,000 - 3,000 RPM's for this engine (stock rev limiter kicks in at about 8,500).

The other is: The reason Honda added a rev limiter to the 250X and 300EX is that the stock rod gives out pretty quickly after about 9,000 RPM. So, a modified black box allows the engine to RPM up to and past the point where the rod is being damaged.

For a really reliable 300EX, your best bet is building a really torquey engine, then you can gear it WAY up, and get speed that way, instead of by increasing engine RPM's.

You might try going up a tooth on the countershaft sprocket and see if that does the trick first. If not, think hard before doing the Black Box mod.

If you still want to do it, Curtis Sparks (phone: 805-872-4343) or Powroll (541-923-1290) can modify your CDI.

 

Thanks for the info Pam. I didn't know the downside of this mod. By torquey do you mean high performance camshafts, high compression piston, and other engine mods? I have them planned for the near future. Thanks again for the info, Mike.

 

Is there a box that advances the ignition curve but doesn't raise the limit alot? This is for a 300ex. Is there any other boxes that would fit the 300EX? Example a XR250 for a 400EX?