250x or 300ex cdi modification - remove rev limiter.

[mscottiel]

does any one know how to remove the rev limiter from the 250x or 300ex cdi boxes. i know it can be done but i just don't know how. i have heard there is a certain spot you drill out but i am not sure. if anyone has had there box modified or knows how to do it let us know. thanks

[Ryanwolfe911]

You really don't want to do that, even if you could. There's a reason why the rev limit is where it is. I tried the same thing and ended up floating a valve right into my piston. You don't want to increase your rev limt without making appropriate valave train modifications, i.e. stronger springs, better valves and keepers, and hardened rocker shafts.

[mscottiel]

thanks for the warning.
i am not worried about breaking something i just want to know how to do it. i know i could just get a 350x cdi and switch the two wires on the small plug and it will work but i was wondering how it is done on the stock 250x cdi.
it can be done i just am not sure how to do it. it would be useful info for those of us with projects or built motors that want to exceed the wimpy yet safe low rev limit of the stock honda cdi.
why do you think hondas have such a great reputation for longevity. they don't let you rev them anywhere near a point where damage can be done. plus the fact they are engineered very well.

[WildWestRacing]

I would like to know how to do this mod myself.

We are building a National motor and this is what some of the top builders in the business reccomend. They will do it for $75.00 to $85.00

I'm sure it's probably a very simple mod.

Bill

[fastex91]

A 250x cdi will NOT work and yes the 350x wire switch method will work. I sent our's to TC and had it done, and you can tell where it was drilled out in the center.

[mscottiel]

what do you mean the 250x cdi will not work? are you talking about putting a 250x cdi on a 300ex? can you post a picture of your cdi?

[Ryanwolfe911]

I don't know about drilling it, but you could probably remove or change one of the resistors in the box that controlls RPM dependent spark.

[fastex91]

Yeh a 250x box will not work on a 300ex.
I could post a picture of my box, but it wouldn't do you any good because TC put a sticker right over the drill hole.

[2muchquad]

i just did the mod a couple of weeks ago.i did indeed drill just a small hole with a 1/8 inch drill bit.this mod does away with the rev limiter PLUS theres no rev limiter in reverse.ITS a VERY SIMPLE MOD,my dumb***** almost spent $90 for a aftermarket box that only gave a extra 1000rpm.i wouldnt pay some company $85 to do this mod for me now that i know how simple it is.took me about 15min to cut some of the rubber off the back of the cdi to expose the circuit board where i would drill,i just siliconed it back up when i was finished,so easy..;)

[300exOH]

Originally posted by 2muchquad
i just did the mod a couple of weeks ago.i did indeed drill just a small hole with a 1/8 inch drill bit.this mod does away with the rev limiter PLUS theres no rev limiter in reverse.ITS a VERY SIMPLE MOD,my dumb***** almost spent $90 for a aftermarket box that only gave a extra 1000rpm.i wouldnt pay some company $85 to do this mod for me now that i know how simple it is.took me about 15min to cut some of the rubber off the back of the cdi to expose the circuit board where i would drill,i just siliconed it back up when i was finished,so easy..;)

You should post a "how to" article on this with pics. :D

[mscottiel]

got a pic and some detailed instructions?