Whats the actual rev limit on the 400ex?

[excess]

I keep reading about the CDI and most say they take the 400s limit from 9300 to 10300.

Does the 400 actually climb to 9300 RPM?

I was looking at a gearing calculator and it shows it goes up to 8250 Stock.

What is the actual number

[airheadedduner]

The stock CDI is limited to about 7900RPM. As far as aftermarket you can get them with no rev limiter but to me it would be pointless. Even modded the EX don't make much power past that. It is more of a midrange machine.

[StreetLegalEX]

But higher rpm leads to higher top speed doesn't it? Or doesn't the 400EX have enough power to go any faster?

The rev-box also seems to do a lot for the entire powerband, makes the bike more snappy to ride. At least that's what I heard from someone who owns an aftermarket CDI.

Actually I would rather have a 6th gear, always want to shift when in 5th.....

[excess]

Thanks for the input but I don't want to turn this into a post about the performance gains or lies about the CDI. Can anyone back up the 7900 RPM limit?

[ZSK]

Might just be me but that sounds awfully low. The 250ex hits rev limiter at 8750rpm (so says 4 wheel atv action) and that's a pushrod engine. About 9000 sounds right. In the rocky mountain atv catalogue it says, "increases RPM from 9300 to 10,300 (1000 RPM gain)."

[Mxbubs]

I believe stock is 9300, and the white bros. is 10600. Dont quote me on that. Some guys say they are bad, some say they are good. I know when I ported my head, and put a bigger cam in, I could not ride it, it kept over revving and cutting out. So I got the white bros, and no prob. after that.

[excess]

Soem people say it doesn't add any horsepower which is fine but I could definately see it helping top end significantly, plus wheeling the bike it shouldnt run out of gear so quickly when doing them in a low gear.

[JOEX]

I haven't been able to confirm the stock rev limit yet but i'd rather spend $15 on the advance key than $100 on a rev box that has known issues. JMO;)

Joe

[excess]

actually I am thinking about getting both, the rev box is just $60 and the ignition key is 15, do you think using both would be a problem?

[JOEX]

Originally posted by excess
actually I am thinking about getting both, the rev box is just $60 and the ignition key is 15, do you think using both would be a problem?
I don't have either so I really can't comment. I thought about getting the key though.
I'm currently saving for suspension upgrades because I know i'm not using the full potential of the stock motor.;)

Joe