The big question, do hi rev CDI's actually make a difference?

[matt1106]

I have a 2002 400ex with a K&N filter, jet kit, and white bros. R-4 slip-on. I'm looking to get a little more power, and i'm running out of easy bolt on performance parts. So I've been looking at the Hi-rev CDI's, from Big gun, white bros, and AMR. Do any of you guys have any experience with them, and can you actually tell the difference. Do u get better acceleration or top speed out of them? Any imput is appreciated

[XXXRACER165]

On your machine you probably won't see a noticable difference.
On mine with all my mods the motor makes power up to and past the stock rev limiter. 400EX's are not high revving bikes to begin with, so it all depends on where your motor makes it's powerband.

[matt1106]

I have an 11.1 compression piston and a stage 1 hotcam, i havent installed yet, do you think after i install those it would benifit from a new CDI

[MO-EX-RIDER]

^^ dump the stage 1 and get a stage 2.....you wont be disappointed

unless you have a big bore or some motor work done internally a rev box wouldnt do much at all for you.

[Wheelie]

Unless the engine is internally modified--don't waste your money. The engine in my EX is highly modified and I'm still running the stock CDI. Rarely do I tag the rev limiter.

Spend your money elsewhere.

well my friend had a rev box and he would always win with the rev box but when he used stock we would run even or he would lose. Then when he got his bigbore the rev box was worth it because those xtra rpms you can go make you pull ahead even more. But thats in a drag race. In typical riding i would spend money elsewhere

[zrpilot]

I have a different CDI and I like it for two reasons:

1) It allows me to start in reverse!
2) Occasionally I do hit the stock rev limiter, nice t have a little extra RPMS just in case.

[Ry007]

I have all bolt on mods along with the Sparks CDI and timing Key
and I must say I did notice a nice improvement! The key allows the timing to be degreed to make more power where as the rest of them can only advance it so far..... Read about it on curtis sparks website. They are second to none in the engine dept.

[my88r]

i had a sparks cdi didn't notice much. other than a little more 1st gear.i sold it after 2 rides

[Ry007]

Originally posted by my88r
i had a sparks cdi didn't notice much. other than a little more 1st gear.i sold it after 2 rides

I bought it from you my88r..... :D The timing key is really the key to get the engine properly advanced.

[matt1106]

Is the timing key difficult to install?

[my88r]

Originally posted by matt1106
Is the timing key difficult to install?

i beleave so. never had one though

[matt1106]

Nevermind, i just read the curtis sparks site and it said its not good to use the timing adavnce with the high compression piston, and i already have and 11.1, so i guess ill just install that and the cam, and see if a new CDI makes a difference with that setup