CDI/REV Box?

[tEXas400]

I know this topic has been beat to death. Despite all the threads I've read on the topic in various forums, I still can't seem to generate a definitive answer on the questions; Is it worth the purchase, or which brand to choose from? Yada Yada Yada..

I'm building a 416EX, new jug, stage 2 Hot Cam, A LOT of extra cooling, New OEM style Wiseco crank, 11:1 Wiseco piston, GT Thunder Heavy Duty studs, full Yoshimura exhaust, 04/05 450R carb, Aluminium open airbox.. and possibly some port matching on the head. Will I benefit from a good CDI/Rev box, or is it just a waste of coin that could have been spent elsewhere?

Thanks in advance.

-J

[Stickman400]

The only one that actually does ANYTHING is a White Brothers rev box, but since they have been out of business for quite some time now they are very hard to come by. They actually changed the timing curve and helped the engine make power where it wants to. All the other rev boxes do is increase the rev limiter by 1,000 RPM and make it harder to start in the winter. If you have reverse they also remove the reverse limiter, so that helps, but if you don't have reverse they are pretty well pointless.

[DragonGunner]

WB is good to go if you find one and it actually is a WB. Scroll down the thread posts and you will see a guy just found and bought one still new in the box, think there may of been another one on ebay for sale, they pop up sometimes, but to find a still new one is rare. The WB are hard starting when very cold also. I have heard guys say the Curtis Sparks is good, but some say its just a type of 250 dirt bike CDI that just raises the rev limit. WB is the only one I ever heard of the changes the rev limit and the power curve. I run the WB and it is much much better than the stock CDI and only one I could really recommend that benefits. Hope you can find one. The only other option is the high dollar dyne tech system, think Duncan still sells it, maybe around 400.00……it changes the power curve and has different settings, Doug Eichner always ran that on his 440EX and won a few Championships in the four stroke class even going against bigger cc machines.

[tEXas400]

I've actually seen a couple of used WB CDI's on eBay for relatively cheap.. Around $30 - $40 dollars.

I might just snag one of them.

[honda028]

I have a wb box if you interested...

[tEXas400]

I have a wb box if you interested...

price?

[tEXas400]

Anybody ever use a Magnum Rev Box?

[DragonGunner]

Anybody ever use a Magnum Rev Box?


So far I've only heard guys on this forum that used them say they are no good.

[CJM]

The only one that works is white bros or a dyna. Everything else is just a xr250 box with a label on it. Been there done that and its the truth.

[honda028]

price?

40 plus shipping

[Wheelie]

Stick with the stock CDI and add a couple degrees timing via cutting the flywheel key. These engines respond very well to added timing.

[tEXas400]

40 plus shipping

PM'd you.

[RNL]

So what's the difference between increasing timing via the flywheel key vs the cdi? Besides the actual process of doing it.

[DragonGunner]

So what's the difference between increasing timing via the flywheel key vs the cdi? Besides the actual process of doing it.


Timing at the flywheel when I put a Sparks in had snappier throttle response, thats about it. Didn't feel like it changed rpm or the power curve.

[RNL]

So with a Dyna and its programable curve you can change, you could change the power curve for more low end or top end depending what riding your doing?

[DragonGunner]

So with a Dyna and its programable curve you can change, you could change the power curve for more low end or top end depending what riding your doing?

Yes, never got one….but Doug Eichner ran one and won a lot of races, including 4 stroke world championship against bigger quads. Think it has 7 programs to choose from and Doug had the bottoms right there to change. He had one for the start to get the hole shots then could change over to a different setting as the track demanded it. That was way back in the day though, today its the 450R and I think guys are running the dyno on some those race set ups also.

[Wheelie]

A timing key adds the same amount of timing everywhere and doesn't affect the rev limiter or starting. Rev boxes add rpm and some add timing. It's hard to find a good aftermarket CDI, a timing key will give similar/better performance gains for a lot less money and better reliability IMO.