what rpm is the rev limit on a 400ex

[bmf400ex]

anybody know?

[Big - D Racing]

9300rpm

[Dune Surfer]

I thought stock is less then that? Big D knows his Shiznit I would believe him

[Big - D Racing]

That is correct and when you get a white bros it raises it to 10,300 Rpm

[Castor-426ex]

you got a wb rev on yours?? i do on mine...i like it...a lot of people dont..but my qaud has always started...and i think it revs diff...

[Big - D Racing]

I did have one, but I didn't like it. I now have the stock one modified by Four Stroke Tech to have no limiter at all ($85), and no hard starting

[400exInMI]

Originally posted by Big - D Racing
I did have one, but I didn't like it. I now have the stock one modified by Four Stroke Tech to have no limiter at all ($85), and no hard starting
what rpms do you turn?

[Big - D Racing]

I take it you are talking about shift point, I shift usually no later than 9500 rpm I would guess. I shift at the point when my engines start to rev hard. Never ride it for to long, with no rev limiter you can cause a lot of damage if you don't know how or when to shift, the rev limiter won't rescue you. I only recommend it for people who are good at shifting, because if you wait too long, there goes your motor.

Why would you want to rev your motor more when the power drops off way before the rev limiter kicks in???

I guess if your racing for lots of money then having one is worth it,,but just being a weekend warrior racer...an aftermarket CDI is not worth the possibility of blowing up an engine just to walk up and get a $5 trophy.

PS..I sold my WB CDI after about 4 months of use,,It felt like it did something but when I took it off I noticed NO drop in power..:huh

[Big - D Racing]

rev limiters don't increase power in any way, they just let you rev higher, which there is no point if you have a stock or mildly modified bike. But, if you have a full built 400ex, it can produce power at higher rpm's where a stock can't allowing the shift points to be higher. That is the reason why you get one. If your bike isn't built don't waste your money.

withthe WB CDI doesnt it give u a different curve which changes where the power comes on?

[Big - D Racing]

That's what a bunch of people think, and they'll tell you they noticed a power gain. Wrong, they didn't gain any power at all, it's all in there head. The only thing you do gain is the abilty of having problems when starting the quad. You can even ask a white brother technician representitive and they'll tell you it just increases the rev limiter nothing else, and it causes hard starting and you need to make sure your battery is fully charged with it.

[Buzzsaw]

From would I understand the mod rev limiter is just a stock xr400 rev limiter for the 400ex.

[400exInMI]

Here is what I don't understand...In NO WAY will changing the rev limit give you hot or cold startability problems.... so why does this box have a characteristic of such, remember it "doesn't change base or advance timing curve?????" as said by big d.......My feeling on it....It must have some impact on the timing (power curve) if it is having a statability problem. please, give your input

[Leo]

Originally posted by 400exInMI
Here is what I don't understand...In NO WAY will changing the rev limit give you hot or cold startability problems.... so why does this box have a characteristic of such, remember it "doesn't change base or advance timing curve?????" as said by big d.......My feeling on it....It must have some impact on the timing (power curve) if it is having a statability problem. please, give your input

The box WB uses is off a kick start bike.. It must see a higher RPM before the bike will fire (to help prevent kickback).. It turns out this RPM level is right about the maximum speed that the starter will spin the motor.. So if you have a high-comp motor, or it's cold out the starter motor won't spin the motor quite fast enough for the box to fire the plug.. make sense? Slap a battery charger on and it provides just enough extra voltage to spin the motor that tiny bit faster so it will start...

On the issue of the rev limit being higher, as far as I've hear there is NO rev limit to the WB box.. Check out GT thunders site, there is a dyno run posted of a bike with a WB box that was at like 11,500 when he let off because he was afraid it was going to blow.. Not good!

Leo

[400exInMI]

hey thanks, that clears a lot up for me. I have been using the trail tech computer and works great, now I just need to get a tach...... thanks again.

check out this tach. i wanna get it so bad

http://www.highlifter.com/store/tach.html

[Pro400EXC]

I don't understand why everyone is wanting to rev the 400ex's guts out,when its not a revvy motor,like a YZ-F or C-dale....

I think its around 4000 and 7500-7800(thats what Duncan racing says) that the 400 mill is happiest,.it doesn't needs its guts to be revved out,to make mo power......

They used a 400 kit,porting,16/36 gearing,and a mid-top cam,with Edlebrok carb,and sai the motor was great for everything,and has such a wide usable power spread,it worked great on everything,mx,and xc....

so why waist the money on the Rev Limiter,if your not really getting anything outta it...Me myself,I have yet to hit the rev limiter while riding......And No,that doesn't mean,i must not be riding Right,it means,i can go fast,without killin it....

[maxoutput]

I installed a tach that holds the highest rpm untill u reset it & my 400ex w/ edelbrock & full LRD will rev.to 8860 the only time i hit it is on the street....in the woods, i think its revin hard but its only around 7500