rev limiter

[illvibetip]

im new to biking and have just upgraded to a hyosung 250 from a 125cc bike.

How do I check to see if it has a rev limiter on and if it does, how can I remove it? (I live in a place where there are few laws regarding bikes so it is not illegal to do so).

Im only asking because i get nothing when my revs are high, although i can push the top speed but slowly. This is second starting point as I had the gears changed before i bought it.

Thanks

[Guest]

Revs are normally limited by the ECU.

[acemastr]

First time you hit a false neutral when taking off quickly = the end of your pistons.

Why would you remove the limiter? you'll just blow the engine.

[Guest]

First time you hit a false neutral when taking off quickly = the end of your pistons.

Why would you remove the limiter? you'll just blow the engine.

 

Bollox, ive redlined my bike on more than one occasion and its been fine.

Did with my YBR too.

Continuous redline yeh i see your point but still.

I think his point is that it limits power, rather than limits at the redline anyway.

[acemastr]

you're missing what i've said completely....

he's removing the LIMITER, which stops the engine over-revving...

REDLINE is the red part of your tacho that says you're nearing the limits of your engine (not really, but manufacturers tend to say that)

if he removes the limiter the engine will rev until the valves start eating the piston and vice versa

[Guest]

you're missing what i've said completely....

he's removing the LIMITER, which stops the engine over-revving...

REDLINE is the red part of your tacho that says you're nearing the limits of your engine (not really, but manufacturers tend to say that)

if he removes the limiter the engine will rev until the valves start eating the piston and vice versa

 

Well my understanding of it, it limits it at the redline

[Decor58]

Depends, it could be a form of restriction like you get on 125s or bikes that are restricted to 33bhp

This would mean it wouldn't actually be able to rev to the red line or anywhere near it and so wouldn't be use it's full potential.

A way to test this if you have a rev counter on the bike is to see if you can get the needle any where near the red line (neutral gear, clutch in to be sure and rev it).

If it reaches red line on the rev counter or near enough then it either doesn't have one or there is no point removing it.

As for how to remove it I can't help there sorry.

[skatefreak]

Sounds to me like hes talking about a restrictor for example:

Restricted NSR125R (intake/exhaust restrictions), will redline up to 13k happily but the punch is left behind around 9k.

Take out these restrictions and it will push hard all the way up therefore in comparison to the restricted bike an unrestricted would push up to the top speed harder/faster (and well over compared to the restricted bike).

If its gains he's looking for as the bike is restricted down from its intended output then go for it by all means but if he's trying to push it beyond its intended levels of performance then although the engine should survive a while it will no doubt knacker the engine out quicker.

Pushing it beond the intended rev range limits will deffinatly lead to heavy damage sooner

Just my thoughts

-Jvr

Ps, what exactly is the bike?

[illvibetip]

Thanks for the replies.

The bike is a hyosung 250 comet.

I don’t think ill screw the engine (at least im not looking to). The revs are running quite low and its preventing me from over taking sometimes in higher gears or getting up hills. Basically, I pull the throttle and its like it goes into neutral – no power at all over certain revs. I can get a high speed but only by keeping the revs low and building up. I’ve had a similar problem in the past (with smaller bike) and it turned out to be the clutch. But like I say, Im pretty new to this and trying to rule out that this is the problem with the accelerator. I read somewhere that a rev limiter would cause this kind of problem.

Ill try the test suggested (re: Decor58) to see if I can get the revs up in neutral. I don’t want to remove it unless its necessary.

cheers

[Guest]

Thanks for the replies.

The bike is a hyosung 250 comet.

I don’t think ill screw the engine (at least im not looking to). The revs are running quite low and its preventing me from over taking sometimes in higher gears or getting up hills. Basically, I pull the throttle and its like it goes into neutral – no power at all over certain revs. I can get a high speed but only by keeping the revs low and building up. I’ve had a similar problem in the past (with smaller bike) and it turned out to be the clutch. But like I say, Im pretty new to this and trying to rule out that this is the problem with the accelerator. I read somewhere that a rev limiter would cause this kind of problem.

Ill try the test suggested (re: Decor58) to see if I can get the revs up in neutral. I don’t want to remove it unless its necessary.

cheers

Hmm clutch slip?

How freely does it rev, e.g. does the revs struggle to climb, or are they still free just the bike doesn't speed up?

Sounds to me like it has been restricted in one way or anther though? But i dont know what or how.

What about servicing? If its due in for a service or mot etc could get them to take a look at it!

[illvibetip]

the gears are fine as long as i don't accelerate too much (about 8/9 to 13 on the rpms)too quickly. If i do, i can pull right back and absolutley nothing happens. Its like i'm revving in neutral. I wouldnt mind too much but its a bit of a pain when im overtaking and i need a bit of extra kick and it just starts rolling. I took it back to the shop and they changed the gears/oil. I took it out and it was exactly the same (thought the gear changes feel better).

I haven't had a chance to check the revs today (in neutral) cos its late so ill have to wait until the morning.

you think its a clutch slip?

[Guest]

You mean its slipping out of gear white accelerating hard? I've had this when i do an improper gear change, but if its just random (ie. changed gear a little white ago) sounds like something more serious? I have been known to get it when i clutch less change gear so dont anymore!

Im sure someone with better knowledge will be along shortyl!

[illvibetip]

thanks,

revs ok when in neutral, so its not a limiter/restricter. ive got a guy looking at it in a shop. he seems to think its something to do with the clutch. its just taken me 15 minutes to describe what a service is, so im hoping itll come back in working order.

thanks again for your comments

[rennie]

sounds like the clutch slipping to me!

where do you live?

[Guest akey]

you're missing what i've said completely....

he's removing the LIMITER, which stops the engine over-revving...

REDLINE is the red part of your tacho that says you're nearing the limits of your engine (not really, but manufacturers tend to say that)

if he removes the limiter the engine will rev until the valves start eating the piston and vice versa

 

Well my understanding of it, it limits it at the redline

 

Chris, in a word no. Most rev limiters kick in a good few thousand rpm after the red line, for example willows FZR 250 redlined at 18,500 rpm and the rev limiter kicked in at 20,000 I know i hit it !!!

The redline is the end of the safe reving area for normal use (although peak power is usually a couple of thou below this so its pretty pointless getting to it in anything but top gear) the rev limiter stops you being stupid.

You will know if you are bouncing off the limiter because you will hear Baaaaaaaaaaaaaaaa ba ba ba ba ba ba as you hit it.

[illvibetip]

Ian - i live in daegu, south korea.

So what im understanding is its to damaging to the engine if i rev too high anyway. -

Does this apply if youre in neutral? and what is a safe rev zone? below 9000?

[rennie]

It's damaging if you rev at or over the red line for any

period of time.

The confusion we have is if you actually mean a rev limiter

or some form of restriction.

restriction can be removed, if legal.

a rev limiter should not be removed,

it's there to protect the engine.

[j4ff]

the power curve starts to drop when you go into the red.Peak hp is just before the red line.

Red line in the busas case starts between 9500-10000rpm.Screaming to the limiter at over 12000rpm produces less power than at 9500.There is no point ever to go into the red.

http://www.road-quest.com/images/Forum/b-king-dyno.jpg

[Hywel]

I'm no mechanic but suddenly / briefly loosing power to the back wheel under hard acceleration sounds like a clutch slip for sure. Either that or it's dropping out of gear... any 'clunking' noises when the power is lost?