need to tell a friend why NOT to get a rev box..

[yellow400ex05]

Ok my friend said he wants to get a rev box but I keep telling him that its worthless and a waste of money because it just bumps your quad closer to blowing up and puts more strain on your engine and that you making almost no power at that RPM..

give me more negatives to putting a rev box on a quad..

What would a kfx be making in HP at the redline?

[deathman53]

alot of the time, they are a waste of money. If the box changes the igntion curve, advances the timing or does something else of a performance thing, it would be a improvement. But, in most cases the motor stopped making power before the rev limit hits and all they do is make the quad hard to start. This is the story with alot of 400ex rev boxes, they are nothing more than xr400 and xr250r cdi's, infact, some, you can see the honda part numbers scratched off. Some of the others, DO change the curves and timing and actaully do something. Your friend needs to spend his money on something better, new air filters, tires/wheels, brake pads, something that actaully does something.

[bwamos]

What the above guy said.

It also depends on the quad. The 300ex for example, even without anything else is benefited by an increased rpm. But some (most) stock quads have an RPM limit high enough that there's little to no usable power left in stock form.

However if that CDI does advance the spark timing, you can find a decent adjustment to the power curve.

[400exrider707]

If its a 400EX most aftermarket boxes for that are simply XR250 boxes and will cause starting problems.

GT Thunder and TC make some nice boxes for the 400EX.

[quad97]

I have ridden 400exs with and without rev boxes and there is a slight difference in power. The extra overrev is nicer when you need to stay wide open in a situation where shifting up would would actually slow you down ex: whoops or uphills. I didn't notice a difference in starting between these two machines either. If it were me I would put a new cdi on the 400ex, they were only a little over $100 for those the last time I checked.

[fmftrx300ex]

I like my rev box cuz on a smaller quad (300ex) it adds alot of room to play and adds speed! the difference between my stock speed and with the box is 10+mph. from 62 to 70mph

Well if you do the math its 13 horsepower from 62 to 75 mph and a stock 450r will like top out at 75 i think or maybe its with a hrc kit but anyways a 300 ex tops out at like 40 lol been there done that on my 300ex with more stuff then yours and it didnt go over 50 i can tell you that much. The only 300ex i know that might hit 70 is someones i know and it is a fully built race quad with everything imagionable done to it. So i am sorry but when you are in your own little fantasy world hitting maybe 45mph and you think your hitting 75 mph dont feel bad when a guy on a moped passes you.

[trx400EXtreme]

Originally posted by fmftrx300ex
I like my rev box cuz on a smaller quad (300ex) it adds alot of room to play and adds speed! the diferenc btween my stovk speed and with the box is 10+mph. from 62 to 75mph u sure about 75? :ermm: :huh

HAHA you must of been posting while I was and didn't see mine.

Originally posted by RoadRidin450r
Well if you do the math its 13 horsepower from 62 to 75 mph and a stock 450r will like top out at 75 i think or maybe its with a hrc kit but anyways a 300 ex tops out at like 40 lol been there done that on my 300ex with more stuff then yours and it didnt go over 50 i can tell you that much. The only 300ex i know that might hit 70 is someones i know and it is a fully built race quad with everything imagionable done to it. So i am sorry but when you are in your own little fantasy world hitting maybe 45mph and you think your hitting 75 mph dont feel bad when a guy on a moped passes you.

250ex 47-50MPH
300ex i think around 57-60MPH
400ex 68-72MPH
450R i think around 78MPH

that would be my guesses on speeds. I know for a fact the 250ex and 400ex and i'm pretty sure my guesses are close to correct.

[pro-rider46]

i think dirtwheels tested the 450r and the yfz and the 450r topped at like 82 mph. and the yfz topped at like 84 or something

FoxHondaRider That seems about right but a 250ex is just as fast as a 300ex in a drag lol. My brother has a 1999 300 4x4 honda dunno if you guys are familiar with them but the 300ex barely beats it lol. I am saying a 300ex is low 50s to mid 50s becuase they are slow as piss in my opinion.

[400exrider707]

This thread turned into a bunch of useless information real fast.

Here's some FACTS for those of you making guesses.

This would help a lot if we knew what machine this was going on...

I'm going to assume this is for a KFX400 simply because that is the machine you asked about.

Most rev boxes on the market simply do nothing more than raise the rev limit. Your assumptions are correct, this will indeed put more strain on internal parts. Will a stock KFX handle it? Yes probalby it will. Since this is a KFX we're talking about you shouldn't experience any starting problems at all. Some of the generic ebay boxes are total crap and a good percentage show up not working. Your money is spent wisely on a good box. If your friend is dead set on getting a box then I would look at a good programmable one myself. It will be a better choice in the long run.

What other mods does your friend have and does he/she indeed run a KFX?

[400exrider707]

Originally posted by fmftrx300ex
I like my rev box cuz on a smaller quad (300ex) it adds alot of room to play and adds speed! the diferenc btween my stovk speed and with the box is 10+mph. from 62 to 75mph

Thanks for the laugh.:D

[400exrider707]

Originally posted by pro-rider46
i think dirtwheels tested the 450r and the yfz and the 450r topped at like 82 mph. and the yfz topped at like 84 or something

Once you drop the name "Dirt Wheels" most people on here automatically will not believe anything typed after that.

A stock one will not do that, but I do believe I know the article you are talking about where they tried different gearing and tire sizes to attain those speeds. If you notice carefully, Yamaha will win nearly everything in their shootouts. Thus the name "Yama-Wheels"

[bwamos]

Originally posted by 400exrider707
Thanks for the laugh.:D

It will add a lot of top speed to the 300ex because of the insanely low stock rev limit. (The 250ex has a higher rev limit). Remember the 300ex is the Lawyerized ATV. But, it's more like 55mph to 62mph w/ stock gearing and tires. ;)

[400exrider707]

Originally posted by bwamos
It will add a lot of top speed to the 300ex because of the insanely low stock rev limit. (The 250ex has a higher rev limit). Remember the 300ex is the Lawyerized ATV. But, it's more like 55mph to 62mph w/ stock gearing and tires. ;)

I understand, but getting a 300EX to 75mph with nothing more than a rev box.... c'monnnn

[trx400EXtreme]

Originally posted by RoadRidin450r
HAHA you must of been posting while I was and didn't see mine. lol yeah.

[fmftrx300ex]

ok maybe not 75 but close it did sixty(read on b4 u laugh) and (i know cuz i had a guy ride next to me with a speedomiter (if u know what that is)) so anyway it did sixty be4 my box, exhaust and sprokets...and power has nothing to do with speed spedtard. You can get a little 50cc to do 100 if you gear it right!!! its ALL ABOUT GEARING!!!!!!!!!!!!!!!! JUST CUZ UR 450S SLOW CUZ UR AFRAID TO PUSH IT! DOESNT MEAN MY 3OOex aint fast! I did the math at 11000rpm (my rev limiter) with my 21in tires and old sprokets it would do 70. thats at 11000rpm dosnt mean its done that iv hit maybe 9000-10000rpm 5th. my cuson has a 660 raptor and fallows me in 4th so up urs 450tard!!!!!! foxhondarider was right stock its like 53-57...75 was a little high i didnt look at my list of #s ... whts on my list... old 1up in rear sprokets the #s are 5th 11000, 70mph, stock rev limiter 52mph... so sry bout this post evry1 else i just get piz*ed when ppl dis my 300ex so my honda 300ex will do about 70(in perfect condisions) so prolly about 65-70 on the trails

ps: iv had two exhausts cobra(load crapy), and fmf(newer better)


my source for math http://www.cosportbikeclub.org/misc/SpeedCalc.html and Know its for street bikes but its still acurate.

[fmftrx300ex]

Thank you to those who respected my mastac and said things like come on and a lil over the top.. like 400exrider707 i apreshate ur kindness

[zeus54]

Originally posted by fmftrx300ex
ok maybe not 75 but close it did sixty(read on b4 u laugh) and (i know cuz i had a guy ride next to me with a speedomiter (if u know what that is)) so anyway it did sixty be4 my box, exhaust and sprokets...and power has nothing to do with speed spedtard. You can get a little 50cc to do 100 if you gear it right!!! its ALL ABOUT GEARING!!!!!!!!!!!!!!!! JUST CUZ UR 450S SLOW CUZ UR AFRAID TO PUSH IT! DOESNT MEAN MY 3OOex aint fast! I did the math at 11000rpm (my rev limiter) with my 21in tires and old sprokets it would do 70. thats at 11000rpm dosnt mean its done that iv hit maybe 9000-10000rpm 5th. my cuson has a 660 raptor and fallows me in 4th so up urs 450tard!!!!!! foxhondarider was right stock its like 53-57...75 was a little high i didnt look at my list of #s ... whts on my list... old 1up in rear sprokets the #s are 5th 11000, 70mph, stock rev limiter 52mph... so sry bout this post evry1 else i just get piz*ed when ppl dis my 300ex so my honda 300ex will do about 70(in perfect condisions) so prolly about 65-70 on the trails

ps: iv had two exhausts cobra(load crapy), and fmf(newer better)


my source for math http://www.cosportbikeclub.org/misc/SpeedCalc.html and Know its for street bikes but its still acurate.



YOU GUYS REALLY PISSED THIS ONE OFF!!!!! I CAN'T UNDERSTAND A THING HE SAID......:cuss: LMAO

[fmftrx300ex]

lol
i ll rewrite it in english later

[fmftrx300ex]

ok my quad may not do 75 but it'll do 70, dont say thts BS i know i can do 70. 65 prolly more consistanr but 70 is quite posible and wht i was sayin bout the gearing is true horsepower dont=speed
you can make a little 50cc do a 100mph if its geared corectly. i gaind 10mph not 13 hp

Ok kid thats why the 450 was hitting the rev limiter and all when i was topped out in 5th gear but anyway little boy you can keep imaginingt things about your piece of junk quad but go race a 450r with stock tires and it will top out at around 75 or so and you are like a half mile back hitting the rev limiter at like 55 maybe 60. It doesnt really matter if you want to keep arguing about this but whatever you say is crap because a 300ex will not do over 75 or whatever the hell you said it was going unless it is like fully built. By the way fmf pipes are crap unless its a 2 stroke.

[zeus54]

Originally posted by RoadRidin450r
Ok kid thats why the 450 was hitting the rev limiter and all when i was topped out in 5th gear but anyway little boy you can keep imaginingt things about your piece of junk quad but go race a 450r with stock tires and it will top out at around 75 or so and you are like a half mile back hitting the rev limiter at like 55 maybe 60. It doesnt really matter if you want to keep arguing about this but whatever you say is crap because a 300ex will not do over 75 or whatever the hell you said it was going unless it is like fully built. By the way fmf pipes are crap unless its a 2 stroke.


hey he might be able to with gearing changed.........i think u guys should race it would be a good waste of time like replying to this.:rolleyes:

rev boxes i have seen blow up a 400ex IMO they are a huge waste of money unless your quad is so powerfull that you always bounce it off the rev limiter which not many people have something like that.

[pro-rider46]

holy crap your 300ex is pushing 11000 rpms. i dont know if thats right or not but back to the 450rs they redline with a average revbox at like 11,200 rpm. dont you think that is a lil extreme on a 300ex, not sayin you cant get rev boxes that high, but normally your getting into hevier valve springs, hd valves and what not.

and i really do think that dirt wheels has a lot of yammys winning things in there, thanks for pointing that out 400exrider707,

back to the subject, a random cheap revbox wont do much of anything, but those programable ones are pretty good. you can program all new ingition curves, new timing, and set rev limiters, and if your quad is efi you can get those efi tuners and they work great too. you can use them kinda like the rev box

[fmftrx300ex]

iv questioned it also but when i bought it it sayed 11000 whts stock like 8000?

[400eXr1d3rZ]

Originally posted by fmftrx300ex
ok maybe not 75 but close it did sixty(read on b4 u laugh) and (i know cuz i had a guy ride next to me with a speedomiter (if u know what that is)) so anyway it did sixty be4 my box, exhaust and sprokets...and power has nothing to do with speed spedtard. You can get a little 50cc to do 100 if you gear it right!!! its ALL ABOUT GEARING!!!!!!!!!!!!!!!! JUST CUZ UR 450S SLOW CUZ UR AFRAID TO PUSH IT! DOESNT MEAN MY 3OOex aint fast! I did the math at 11000rpm (my rev limiter) with my 21in tires and old sprokets it would do 70. thats at 11000rpm dosnt mean its done that iv hit maybe 9000-10000rpm 5th. my cuson has a 660 raptor and fallows me in 4th so up urs 450tard!!!!!! foxhondarider was right stock its like 53-57...75 was a little high i didnt look at my list of #s ... whts on my list... old 1up in rear sprokets the #s are 5th 11000, 70mph, stock rev limiter 52mph... so sry bout this post evry1 else i just get piz*ed when ppl dis my 300ex so my honda 300ex will do about 70(in perfect condisions) so prolly about 65-70 on the trails

ps: iv had two exhausts cobra(load crapy), and fmf(newer better)


my source for math http://www.cosportbikeclub.org/misc/SpeedCalc.html and Know its for street bikes but its still acurate.

http://home.earthlink.net/~gellett/400ex.htm

[400exrider707]

Originally posted by fmftrx300ex
ok maybe not 75 but close it did sixty(read on b4 u laugh) and (i know cuz i had a guy ride next to me with a speedomiter (if u know what that is)) so anyway it did sixty be4 my box, exhaust and sprokets...and power has nothing to do with speed spedtard. You can get a little 50cc to do 100 if you gear it right!!! its ALL ABOUT GEARING!!!!!!!!!!!!!!!! JUST CUZ UR 450S SLOW CUZ UR AFRAID TO PUSH IT! DOESNT MEAN MY 3OOex aint fast! I did the math at 11000rpm (my rev limiter) with my 21in tires and old sprokets it would do 70. thats at 11000rpm dosnt mean its done that iv hit maybe 9000-10000rpm 5th. my cuson has a 660 raptor and fallows me in 4th so up urs 450tard!!!!!! foxhondarider was right stock its like 53-57...75 was a little high i didnt look at my list of #s ... whts on my list... old 1up in rear sprokets the #s are 5th 11000, 70mph, stock rev limiter 52mph... so sry bout this post evry1 else i just get piz*ed when ppl dis my 300ex so my honda 300ex will do about 70(in perfect condisions) so prolly about 65-70 on the trails

ps: iv had two exhausts cobra(load crapy), and fmf(newer better)


my source for math http://www.cosportbikeclub.org/misc/SpeedCalc.html and Know its for street bikes but its still acurate.


Chill little guy. At no point did I diss you or your quad. If you notice my sig, you'll see I'm looking for a 300EX myself, so dont be so quick to judge. Your top speed seems to be stretching the truth. Checking top speed on a gearing calculator means nothing in real world experience. A gearing calculator doesn't factor in wind resistance, rider weight, machine weight, traction, friction. Just because the gearing calculator says 70, does not mean you will do 70. It started at 75mph, now we're at a "consistent 65" You dropped 10mph off of your top speed already. 65mph seems more achievable.

Also of course you can gear a 50CC to do 100mph, but it doesn't mean its going to have enough power to pull that gearing;)

Also did you call me a spedtard? :confused:

[LEOGM5150]

wow! 75 on a stock 300ex i am gonna have to sell the 440ex i am building and buy one of those if it is faster already.

[gnccguy]

I had a 02 300ex with a 11.5:1 wisco piston, hardend rockes, cam, stage 2 jets, k&n filter. I was running a 36 tooth sprocket and what ever factory front was i forget and 20in tires and a 400 forman 1 of the older 1s would out ran me 400ex would eat me i was running stock rpm tho and hit the limiter quick

[fmftrx300ex]

when i race my dad , who has a stock z400, i really let the rpms get up. and ill have him by a lenght off the line bout half way through he'll pass me and get 1 1/2 on me and we both always finish in 3rd grear so its fast beleav it or not. ill record our next drag race n put it on youtube.com for all of u

Your dad must have a defective z400 then or else he blows at riding. There is no way a 300ex will even think about keeping up with a z400 in a drag race unless its got like a baldwin motor. lol Go ahead and record it but that shows nothing becuase your dad probably blows at riding and your probably worse.

stock rev limiter on my 400ex is 9100 RPM's

[400eXr1d3rZ]

Originally posted by FoxHondaRider
stock rev limiter on my 400ex is 9100 RPM's

8250RPMs.

are you getting that off the 400ex conversion thing?

[fmftrx300ex]

to: RoadRidin450r

EDIT JOEX:
***DELETED*** Talk about being rude....:ermm:


and how would u know how fast a 300ex goes do u have one i dont think so so shut up seriously. were supposed to help this guy convince his friend not to get a rev limiter not bust on my first quad dee dee dee

Haha well if you were over 10 years old and learned how to read before you post you would of seen in one of my other posts that I do have a 300ex and it is the biggest mistake I ever made buying it. Also you look real tough saying things by Carlos Mencia. I would pick on people my own size but people my own size arent as stupid as you and think before they say some bs.