300ex Cdi

[Nuckenfuts]

I was looking on ebay, and found a couple CDI boxes for the 300EX made by AMR Racing. There were Stage 2 (1000rpm gain) and Stage 3 (1200 RPM gain). My 300EX has full Big Gun exhaust, stage 2 jet kit, and K&N filter.
Do I need to do further upgrades (cam, high compression piston, valve change, etc...) before I install one of these CDI boxes?

You do not have to upgrade but don't rev it till it hits the revlimiter b/c the stock motor probably will no be able to take 1000rpms.

[rooster300ex]

Yea I was wondering the samething. It says it removes the reverse rev limiter. I've been in many situations where if i could get the tires spinning alil faster i could of got out of it. Sometimes when i'm giving it hell it will hit the stock rev limiter and it seems like its still making power when it hits it. I wonder if not having my counter balancer in my motor and reving it higher will damage it. It hasn't done anything to the motor so far. It just vibrates alil more.

[bwamos]

How exactly do these CDI's remove the reverse limiter? The reverse limiter is a seperate unit. ;)

A stock 300ex w/ pipe, filter, rejet can easily pull an added 1000-1200 rpms over stock limit.

The 300ex stock limit is around 7600 rpm. Not the ~9000 rpm limit you're used too on other quads.

See picture.
3 = CDI
8 = Reverse Inhibitor

[Nuckenfuts]

If this CDI won't eliminate the reverse limiter, how do I do that?

[bwamos]

There's 2 wires below coming out of the right sidecase below the brake pedal. Usually marked R & N.

N = Neutral
R = Reverse

Take the one marked R off of the switch and ground it.

All done.

Reverse light will no longer work as you bypassed the switch to turn it on. The neutral light will just stay on. Also you'll be able to start it in reverse.. wich can be handy.

If you kill yourself going 25mph in reverse don't blame me.. lol.

[rooster300ex]

So there lyin to us?

[2muchquad]

No they arent.I have done the cdi mod which totally ERASES the rev limit and also does away with it in reverse.Its just a stock cdi with a resistor drilled out thats all.;)

[bwamos]

I suppose it's possible.

The seperate unit could, perhaps, send a signal to the CDI switching it to a lower rpm setting.

I'll have to break out the schematics this weekend and see if I can get a difinitive answer.

I do know bypassing the Reverse switch will eleminate the reverse rev limit, and put it at your normal rev limit.

[Caseys 300ex]

Originally posted by bwamos
There's 2 wires below coming out of the right sidecase below the brake pedal. Usually marked R & N.

N = Neutral
R = Reverse

Take the one marked R off of the switch and ground it.

All done.

Reverse light will no longer work as you bypassed the switch to turn it on. The neutral light will just stay on. Also you'll be able to start it in reverse.. wich can be handy.

If you kill yourself going 25mph in reverse don't blame me.. lol.

Well today i did the reverse modification^^^^ and it works awsome. So if you want to get rid of your normal reverse rev limit i recommend doing this.

[Nuckenfuts]

Once I recieve my new CDI and try it out, I'll see how the reverse works. If I'm not happy with the reverse rev limiter still, I'll try your method.

[Nuckenfuts]

bwamos,

Do you know where I can find other schematics online? I'd like to find some for an old dirtbike I have sitting at home.

[3exrider23]

well i bought a big gun cdi box for mine that goes up 700rpms n all i have is turf taimer 20 inch tires, k&n filter, holes in the airbox, yoshi slip on, dyno stage 2 jets, n the big gun cdi box n mine works fine

[dork]

the reverse inhibitor does just that, it gets the signal from the reverse switch and interrupts the signal from the start button. but it doesn't contain a rev limiter. the cdi contains the rev limiter, which is the same circuit in forward or reverse. the only difference is the reverse switch tells the cdi to kick in the limiter at a lower rpm. so if you remove the rev limiter circuit, it takes it out of reverse too like 2muchquad said. and it was a capacitor you drilled out 2muchquad;)

[bwamos]

Originally posted by Nuckenfuts
bwamos,

Do you know where I can find other schematics online? I'd like to find some for an old dirtbike I have sitting at home.

No clue. I use the schematics in my Honda Service Manual and Clymers.

[rooster300ex]

Originally posted by Nuckenfuts
Once I recieve my new CDI and try it out, I'll see how the reverse works. If I'm not happy with the reverse rev limiter still, I'll try your method.


Which cdi did ya get the stage 1 or stage 2.

[GPracer2500]

Originally posted by Nuckenfuts
bwamos,

Do you know where I can find other schematics online? I'd like to find some for an old dirtbike I have sitting at home.

Bike Bandit has a bunch...

[Nuckenfuts]

Got the stage 2 from AMR Racing. They also have a stage 3. I found it on ebay.

[rooster300ex]

Originally posted by Nuckenfuts
Got the stage 2 from AMR Racing. They also have a stage 3. I found it on ebay.


Ya i noticed that. I seen the stage 2 & 3 also. Don't forget to let us know how it works and performs.

[Nuckenfuts]

Originally posted by GPracer2500
Bike Bandit has a bunch...


Thanks Bud. That's the site I found before, but couldn't remember what it was.


I just recieved the CDI for the 300EX today. I'll istall it tonight and let everyone know how it works.

[Nuckenfuts]

Originally posted by rooster300ex
Ya i noticed that. I seen the stage 2 & 3 also. Don't forget to let us know how it works and performs.

Okay. I've installed the AMR CDI, which actually replaces the Reverse Inhibitor, not the CDI itself. It's simply to install, just unplug stock inhibitor, or plug in new inhibitor. Only differece with installation of AMR unit, is that the single wire that attached to the stock unit has no place to plug in. I believe this is what made the neutral and reverse lights work before, but with the AMR unit you lose your lights.
Performance wise, the reverse rev limiter is gone, so you go faster, but not too fast, because you only top out the one gear. But it will help with backing out of certain situations. Top end I didn't really notice a big improvement. I didn't try to get it to top speed in top gear though, so maybe it will give a little boost. My 300 likely tops out before it hits the rev limiter to 5th anyways, the way it is now.

[TRXNIGHTRIDER]

my cousin got an aftermarket cdi(rev box) for his 300ex and it made the biggest difference. with that, fmf megamax pipe and header, k&N, and stage 2 jet kit, he could beat a stock 400ex bottom and top end somehow

[rooster300ex]

Originally posted by Nuckenfuts
Okay. I've installed the AMR CDI, which actually replaces the Reverse Inhibitor, not the CDI itself. It's simply to install, just unplug stock inhibitor, or plug in new inhibitor. Only differece with installation of AMR unit, is that the single wire that attached to the stock unit has no place to plug in. I believe this is what made the neutral and reverse lights work before, but with the AMR unit you lose your lights.
Performance wise, the reverse rev limiter is gone, so you go faster, but not too fast, because you only top out the one gear. But it will help with backing out of certain situations. Top end I didn't really notice a big improvement. I didn't try to get it to top speed in top gear though, so maybe it will give a little boost. My 300 likely tops out before it hits the rev limiter to 5th anyways, the way it is now.



When you say you lose your lights your just talking about the neutral light and reverse lights on the top of your headlight.Right? That doens't matter to me if thats what ya mean, cuz i have trial tech lights with a chrome toggle switch on the light mount.

[Nuckenfuts]

Yes, I'm talking about the reverse and neutral lights. Headlight and taillight are not affected.

[rooster300ex]

Go and top that sucker out in 4th & 5th and see if you can tell a difference.