A good Rev Limiter????

[twisted threads]

what kind of rev box do you guys have? Is it any good? Does your bike start hard? Sorry for all the questions I want to get one and I dont want any starting problems.:D

they will make it harder to start and all they do is give u another 1000 rpms when the quad stops making power there already. i dont recomend them

[OutlawEX]

I used a white brothers

[Colby@C&DRacing]

I have a sparks on my bike but they are all the same box so it really does not matter:)

[Chanman420q]

is there anyway to make it start easier with the rev box?

[ATVer14]

You can do what I do, but it is a slight inconvience. Just hold on to your stock box, and use it to start the bike and warm it up, then, when everythings ready to go, shut the bike down and install the WB CDI. It is a slight inconvience, but the CDI isn't that hard to get to, at least with the plastics I have. There isn't any way to make the WB CDI easier to start, unless you replace the battery with a much stronger one. Just an idea.
Ken

[Bunkerking217]

Id reccomend one if you have a modded engine. They are pretty much all the same just with a different name on them. You can also send your stock one in somewhere(i forget) and its cheaper. You can't really do it yourself unless you know where to drill it, and if you mess up, your screwed.

[Steve-o 400EX]

Originally posted by Colby@C&DRacing
I have a sparks on my bike but they are all the same box so it really does not matter:)

Yea, they are all pretty much the same. I'd recommend it for a modded engine. The only time i heard they are hard to start is in the winter when it is really cold. During the summer you should not have any problems starting it.

[shamisc]

Originally posted by Bunkerking217
Id reccomend one if you have a modded engine. They are pretty much all the same just with a different name on them. You can also send your stock one in somewhere(i forget) and its cheaper. You can't really do it yourself unless you know where to drill it, and if you mess up, your screwed.



That would be Pro-FabATV.com

[Big - D Racing]

No they are not all the same. Some are, but many aren't. Some change your ignition curve some don't. Some increase by 1000rm others go to 1100, 1200, 1500 and even up to unlimited rpms. Best bet is to pay $75 for four stroke tech. You send your stock one in, and they modify it for you. They keep stock ignition curve, with unlimited rpms. This also prevent hard starting because it is still the stock box.

[Steve-o 400EX]

Originally posted by Big - D Racing
No they are not all the same. Some are, but many aren't. Some change your ignition curve some don't. Some increase by 1000rm others go to 1100, 1200, 1500 and even up to unlimited rpms. Best bet is to pay $75 for four stroke tech. You send your stock one in, and they modify it for you. They keep stock ignition curve, with unlimited rpms. This also prevent hard starting because it is still the stock box.

Yea but one of the main points of getting an aftermarket cdi is the modified curve so it will perform better at higher rpms, thats why they extend the rev limit. The stock curve is not set up for really extreme rpms, this is also why it is harder to start, its meant for high rpm riding.

[Big - D Racing]

I f you talk to most engine builders they will tell you advancing the ignition curve on a big bore engine causes you to lose power. The recommend leaving it stock. Talk to curtis Sparks.

[Steve-o 400EX]

Yea, I'm gunna leave mine stock. I dont wanna mess with that kinda stuff.

[Chanman420q]

they say it ads a solid 2 hp... but really i dont think its really gunna do you any good but in 5th gear when those extra 1000rpms kick in. ( i think )

[NTPRacing#19]

it doesnt add anyhorse power waht so ever, just better ignition curve and more rpms, i have a Sparks limiter and it works good i like it cause i like to keep my quad up where the power kicks in that is mainly the reason you get one is so when you shift your in that powercurve and not down in the bottom of the ignitioncurve where power has to build up. thats my thoughts about a higher revlimiter

[Chanman420q]

soooo rocky mountain atv has false advertisement when they say "· This kit eliminates the frustration of having the restrictive stock
ignition cut out
· This easy to install CDI provides a more aggressive advance curve
compared to stock
· Adds 2 full hp. "

:o

[NTPRacing#19]

it may add two horse in one part of the powerband and it may also take away two horse at say the bottom of the curve. they will say just about anything for people who dont know anything so they will buy the product.

[Chanman420q]

okay... but its still 2 hp somewhere

[NTPRacing#19]

but you lose it somewhere else so basically no gain lol.

[RAPTORAZ]

Originally posted by Big - D Racing
I f you talk to most engine builders they will tell you advancing the ignition curve on a big bore engine causes you to lose power. The recommend leaving it stock. Talk to curtis Sparks.

I have a White Brothers box on my 416. And my buddy has a modified stock box on his 440. We have interchanged our boxes a few times and have come to the conclusion that both of our bikes are quickest with the White Brothers box. Not all modified engines are the same. Some like more timing than others.

[twisted threads]

Originally posted by Big - D Racing
No they are not all the same. Some are, but many aren't. Some change your ignition curve some don't. Some increase by 1000rm others go to 1100, 1200, 1500 and even up to unlimited rpms. Best bet is to pay $75 for four stroke tech. You send your stock one in, and they modify it for you. They keep stock ignition curve, with unlimited rpms. This also prevent hard starting because it is still the stock box. Thats a good idea! I don't really care about the ignition curve but I do what a bike that will start for me and have a few more RPM's to work with.:cool:

[Mr_Bub400ex]

doesnt the more RPMS on the top end translate into a higher top end? thats one of the reasons i want one. anyone hear anything about the big gun box?

[fire x 2000]

I have a WB box and a stock xr400 dirt bike box and i cant tell the difference. The one thing that i can say if your plan on riding in temps below 40 to 50 degrees, then plan on using your stock box. Once it gets cold out the bike only back fires like a mo~fo when u try and start it. The xr box is only $80 and the WB is some where around $120 You make the decision

[Big - D Racing]

Yhe higher the pms doesn't mean the more top end power you will have. Actually you have less power in that extra 1000 rpm range. Here is why, your stock 400ex prodces its peak horse power of @ 28 at like 7200 rpm as soon as it hits 7300 it drops to like 27.9 by the time it hits 9000(where the stock rev limiter kicks in) your at @ 24 hp or even less. If you add 1000 more rpm you'll be at like 22-23 hp. A good rider knows where to shift and the shift point would be like 7300rpm while you are still making optimal power. If your riding above that mark in any gear your just losing power. The only reason to get a rev limiter is if your bike can continue producing horsepower that high of rpm's. I have yet to hear of a 440ex that can even do that let alone a stock 400. Talk to Duncan Racing they run the stock rev limiter in their national race 440 engines, that includes Doug Eichner's winning world class 440. They'll tell you they do you no good and they cause hard starts. I would only get one if I had a heavy built 465 stroker or bigger, because those engines can produce power that high. Check out this dyno I compares a 425 to a stock 400 look at where the top hp is and then how it falls on both bike after that rpmwhat would be the point to go another 1000 rpms?

[Porkchop]

what if you shaved the fly wheel?

[ATVer14]

I'm surprised no one's cited this dyno run. Here's the truth about rev boxes.

[Razorback]

"No it didn't shut off at 11.2k--I chickened out" - now that's funny. I guess the limiter part isn't working. That is a good dyno. Shows that there are very minimal gains with the box. Maybe 1 hp or so here or there, but nothing significant.