rev box

[linkindust313]

i have a wb rev box that i bought off of my buddy for 50 bucks. Are these things really junk? i would buy a TC or something but i heard that they also increase your timing, which i have already done with the sparks key. Would it be over-timed if i used one of these?

[nakomis0]

WB rev box also increases timing.

I have a sparks degree key and a wb box and its 'over-timed'. It won't start. I use the stock box now.

[cheatin mother]

I have a white bros box with the key and have NO problems. Starts and runs great !

[nakomis0]

Thats interesting to hear...^^^^. My crap won't start with the key and rev box, and it really pisses me off cause I want the higher RPMS.

Different combos work for different peeps I guess.:)

[cals400ex]

i don't think the WB box "advances" the timing. however, the WB box may make the bike hard to start.

[nakomis0]

I'm 100% positive it does increase timing. Its just a re-labeled XR box.

[linkindust313]

i rode it yesterday with the WB rev box on and it seemed like it was dogging so i figure it is "over-timed" im going to put the stock rev box back on. DOes anyone know how to raise the rpm's without advancing the timing also?

[Quadzilla]

What I have read is that the WB (and most other boxes) raise the RPM by 1000 and advance the timing a hair. I believe that the TC box does not advance the curve (call them to verify for sure). Most units will give you starting issues especially if it's cold outside (making the oil thicker and making the motor harder to turn over). The boxes that are XR250 rebadges need a certain rpm to get to before giving spark to the plug which a 400EX with a fairly fresh battery in fairly mild climate has no issues doing. TC and GT Thunder do not use XR boxes, hence the easier starting. You could also go with a SParks box. I believe that they are stock EX boxes that just have the rev limiter eliminated completely. There is a slight risk of blowing the motor with one of those if reved too high for too long....

[daimon1054]

The rev box is a waste of money on a stock motor, the useable power is falling off befor the rev limiter kick in, so increasing the revs is worthless. Now if you built you motor to rev then OK but the old school 400ex motor does not like to rev so you only hurting yourself there.

Heck I just got back from the Red Bud MX and RC, Reed and Kevin were all short shifting and lugging the snot out of their 450 motors so it seams Honda and Yamaha have learned that revs are not the key even on super high tech motors.

[TC426EX]

The TC box does not advance the timing, but the GT thunder does...

[Quadzilla]

Originally posted by daimon1054
The rev box is a waste of money on a stock motor, the useable power is falling off befor the rev limiter kick in, so increasing the revs is worthless. Now if you built you motor to rev then OK but the old school 400ex motor does not like to rev so you only hurting yourself there.

Heck I just got back from the Red Bud MX and RC, Reed and Kevin were all short shifting and lugging the snot out of their 450 motors so it seams Honda and Yamaha have learned that revs are not the key even on super high tech motors.

Daimon is right. The stock EX motor even with a pipe and jet kit hp peaks out way before the stock rev limiter kicks in. I could feel the power falling off significantly before the limiter kicked in. My new motor wants to rev to the moon. I actually needed a rev box after I got the new motor because 1st and 2nd would nail the stock rev limit so fast, they were virtually unusable with the stock rev box...

[cals400ex]

i agree. on a stock motor, it was no benefit. on my 406 with stage 2, it was near manditory. i mainly drag race and i would hit it in the first 3 gears. i have even hit it in 4th, but not normally.

the sparks box made mine hard to start. i got rid of that thing and i am looking for a new one. i am debating on the TC and a few adjustable ones....