is eliminating the rev limiter dangerous?

[300ex03_619]

i am considering purchasing a curtis sparks rev box which eliminates the rev limiter on my 300ex, is this dangerous or harmful to my engine?

[CannondaleRider]

If the 300EX is able to pull much higher then the stock limit....then yes, its bad for it.

The rev limiter is there for the reason. You can usually raise a limiter safely, to a point, but I wouldn't eliminate it if it was my choice.

[hardkoratvmxr]

if you fully eliminate it you can float a valve. and i believe i saw a dyno run of a 300ex with a 1,000 iuncrease rev box and one with an unlimited one and with the 1,000 it saw an increase but on the unlimited one after the initial 1,000 it saw no increase in power

[bwamos]

I'm running a +2000 rpm rev limiter on my 300ex. Puts the rev limit at 9600rpm. Stock is 7600 rpm :huh

Curtis can probably make it a +1000 rpm limit. I know he does it on the 250x. I had mine done my Mickey at FST.

+1000 rpm a semi-stock motor is perfect. You can run that thing at 8600 rpm without any worry whatsoever.


Note: I cant remember off the top of my head exactly what the stock rev limit for the 300ex is, but I know it's in the mid 7000 range. Very low.

[Trevor]

I hardly ever hit my limmiter but with 1k extra rpm your top speed should go up a noticable amount if you able to pull it!

[bwamos]

I would reccomend dropping the gearing slightly when increasing the rev limit.

I really liked my increased rev limit w/ slightly shorter gearing.

if you're running 22" tires you could try 12/37 gearing.
Gearing will drop top speed from 55 to 52mph. But the extra 1000rpm will knock it back up to 59mph. More acceleration, and more top speed at the same time. ;)

13/36 on 20" tires is about the same.

[Cody_300ex]

Originally posted by bwamos
I'm running a +2000 rpm rev limiter on my 300ex. Puts the rev limit at 9600rpm. Stock is 7600 rpm :huh

Curtis can probably make it a +1000 rpm limit. I know he does it on the 250x. I had mine done my Mickey at FST.

+1000 rpm a semi-stock motor is perfect. You can run that thing at 8600 rpm without any worry whatsoever.


Note: I cant remember off the top of my head exactly what the stock rev limit for the 300ex is, but I know it's in the mid 7000 range. Very low.

What kind of rev-box are you using? How Much was it?

[bwamos]

Four Stroke Tech modified stock box. Think the mod was like $80 (been years so I can't be exact).

[deathman53]

I know that 350x cdi boxes were used on trx250x motors for years for a cheap way to get rid of the rev limit, if done carefullly, you can get rid of the rev limit and get more power due to being able to rev it more. But also these guys also didn't have stock bikes(far from in most cases) and had their motors rebuilt/replaced very frequently. If you motor doesn't make anymore power past the stock rev limit, why increase the revs, a modded motor is a different story, also modded motors and typically raced and rebuild more often.
I would increase it by 1000 rpm and leave it alone, the stock rev limit is kinda low, but don't get into the habit of running it real high in the rpm range. You will notice some difference with the increased rev, but the real gains for it are with a modded motor and a motor that makes more top end than a stock motor.

does a 250x have a rev limiter?:huh



i dont think mine does :huh

[GPracer2500]

Just so we're all on the same page; a rev limiter isn't a "thing", it's a function of the CDI. When the RPMs reach a certain number the CDI stops delivering spark and the show ends...

Originally posted by Moto49X
yes yours does....it is the little black box.

I ran an unlimited on my 250x for a couple years and never had a problem.


so i could just mash the throttle and it would go blah blah blah blah
and not hurt anything?

ive never tryed because i didnt know mine had one :huh


my old one did

[fandl450r]

Just about everyone has one, in fact I can't think of one that does not. If the rev limiter would be removed. Your engine could rev to the moon and almost indefinitely something would fail and your motor would become scrap metal.

Originally posted by fandl450r
Just about everyone has one, in fact I can't think of one that does not. If the rev limiter would be removed. Your engine could rev to the moon and almost indefinitely something would fail and your motor would become scrap metal.


ive reved it pretty high before and never hit the limiter

but i thought it didnt have one so i didnt try to hard

[DieselBoy]

A rev limiter is crutial. in any situation like carelessness, or an accident, where the CDI is not indicated to disrupt the over-revving, the engine may self destruct, and it most certainly would.

[deathman53]

many 350x motors blew because they don't have rev limiters, raise it if you want, but don't get rid of it