CBR 250 Rev Limit

[KRS1]

Has anyone successfully removed the rev limiter from the CBR 250, or atleast been able to up it by 1k rpm or more ?

Would really like it go a bit higher than 10.5k.

[VocalNeal]

Tyga can tune IgniTech units maybe there is one for the CBR250? seen some videos from Indonesia!

What have you done to the bike to need an extra 1000? Stock power as you know drops of after 9000-ish, lower if you have an after market pipe.

[KRS1]

at 10.5k she's still climbing, just remove the air filter and do some adjustments with the CCT to relieve it of some tension.

[VocalNeal]

What does it top out at?

I guess if the ratios are quite wide then on a slight hill you might benefit a little on an up-shift but most dyno graphs look like this.

A cam with a bit more top end maybe. They do race them here.

EDIT: here ya go.

Takegawa FI Con for Honda CBR250R is an adjustable fuel injection control module that contains 16 pre-programmed ignition maps of varying performance. Ideal for owners who have upgraded with Takegawa high compression piston kits, air filters, Power Silent Oval Exhaust, or high lift camshafts. Increases rev limiter to 12,000 and installs easily into your existing wiring harness. Simple rotary dial adjuster for fast tuning.

[mania]

at 10.5k she's still climbing, just remove the air filter and do some adjustments with the CCT to relieve it of some tension.

You mean at 10.5k you feel the engine is still pulling?

Or you mean you see the speedo rise?

[RubberSideDown]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

[Gsxrnz]

Removing the rev limiter will generally be of no material benefit unless you manage to get more power at higher revs, thus raising your power peak. That will involve cams/valves/fuel/mapping etc.

When you say that she's still pulling at 10.5k, is that in top gear, or in the lower gears? Usually any additional revs in top gear are not worth the effort as it takes longer to climb in the revs once beyond your power peak. The same also applies to lower gears as effective power is lost by red lining.

You'll find you'll get to maximum speed quicker by upshifting immediately prior to the power peak - looks to be around 9k - I'd shift at 8k or thereabouts. Running to or past the redline is a total waste of time in racing terms - power rolls off so fast beyond the peak point that acceleration slows dramatically.

If you want to get there quicker, consider playing with your sprockets. One tooth off the front will make it pop quicker to max speed, but of course the max speed will be lower. Quick upshifting is necessary so unless you can upshift without the clutch and preloading the lever, this might actually slow you down.

And just a word of caution - if you're at full revs for more than a split second (regardless of the gear), you are using 100% of your available power. This leaves you in a situation where if you ever need to accelerate to avoid an incident, you cannot. Acceleration, slowing, avoiding, are the only choices you have - full revs eliminates 1/3 of your options.

[KRS1]

What does it top out at?

I guess if the ratios are quite wide then on a slight hill you might benefit a little on an up-shift but most dyno graphs look like this.

A cam with a bit more top end maybe. They do race them here.

EDIT: here ya go.

Takegawa FI Con for Honda CBR250R is an adjustable fuel injection control module that contains 16 pre-programmed ignition maps of varying performance. Ideal for owners who have upgraded with Takegawa high compression piston kits, air filters, Power Silent Oval Exhaust, or high lift camshafts. Increases rev limiter to 12,000 and installs easily into your existing wiring harness. Simple rotary dial adjuster for fast tuning.

Right now its at 168kph crouched 158kph upright, i need to shift at a higher rpm so the rpms dont drop so much per shift.

Going to do more work on airflow before i pull the internals apart.

thanks for the info

[KRS1]

at 10.5k she's still climbing, just remove the air filter and do some adjustments with the CCT to relieve it of some tension.

You mean at 10.5k you feel the engine is still pulling?

Or you mean you see the speedo rise?

Yes the engine is still climbing before 6th, still pulling.

Just so its clear, im after more acceleration with no top speed loss. I need to shift at a higher rpm.

[KRS1]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

Been researching it, i believe its a function of the oscillating crystal...i could change the frequency but, its going to open a can of worms.

[mania]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

Been researching it, i believe its a function of the oscillating crystal...i could change the frequency but, its going to open a can of worms.

It could

Their valve springs are rated

If your increasing beyond that they may be too soft

Valve float would require stiffer springs too.

And that could just be the start

Just depends how far you want to go with it I guess

If your getting 168 I am a bit surprised already

I did not realize that cbr could do 168

[VocalNeal]

You have to allow for speedo optimism. I would say 168 is about 155 or less. To get 168 real you'll need about 32 hp. If you can measure with GPS i can update my formula

Depending on valve lift you could use other Honda's double valve springs for bikes with power at higher RPMs.

[KRS1]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

Been researching it, i believe its a function of the oscillating crystal...i could change the frequency but, its going to open a can of worms.

It could

Their valve springs are rated

If your increasing beyond that they may be too soft

Valve float would require stiffer springs too.

And that could just be the start

Just depends how far you want to go with it I guess

If your getting 168 I am a bit surprised already

I did not realize that cbr could do 168

me either, thats why im choosing to push forward and see what its really capable of.

I need to look at the rpm's next time i do a run.

[RubberSideDown]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

Been researching it, i believe its a function of the oscillating crystal...i could change the frequency but, its going to open a can of worms.

It's not the same bike, but I just raised my rev limit by 500rpm through flashing the ECU- I would imagine it's the same for any recently-made motorcycle.

[thaicbr]

I think you're going to have to flash the ECU to change the limiter- it's not an easy thing to do.

Been researching it, i believe its a function of the oscillating crystal...i could change the frequency but, its going to open a can of worms.

smash it with a hammer... those damn oscillating crystals

[RubberSideDown]

You'll find you'll get to maximum speed quicker by upshifting immediately prior to the power peak - looks to be around 9k - I'd shift at 8k or thereabouts. Running to or past the redline is a total waste of time in racing terms - power rolls off so fast beyond the peak point that acceleration slows dramatically.

Why would you shift before peak power if you're looking for maximum performance? The point of running past the peak of the power curve is so you're in the heart of it when you up-shift- if you're short-shifting, you're falling behind. Racers always set their shift lights after the peak.

Look at the dyno chart- the bike puts out ~the same hp at 8K and 10K (using the stock curve)- if you shift at 8K you're dropping about 2500rpm on the upshift and falling way short of peak power- if you shift at 10K and drop the same 2500rpm, you're right back in the power curve, and will have utilized peak power- short-shifting will never accelerate as quickly as you're never using full power.

[pokerkid]

I dont think its worth the money to change the rev limiter, time to trade the cbr in for the baby ninja. They have dropped in price lately due to the 300 being released.

[mania]

I dont think its worth the money to change the rev limiter, time to trade the cbr in for the baby ninja. They have dropped in price lately due to the 300 being released.

Agree & even some steals for a year or two old now

This is a 2011 with only 1400km on the clock

89k At Pekky Prostreet Chiangmai

[pokerkid]

I dont think its worth the money to change the rev limiter, time to trade the cbr in for the baby ninja. They have dropped in price lately due to the 300 being released.

Agree & even some steals for a year or two old now

This is a 2011 with only 1400km on the clock

89k At Pekky Prostreet Chiangmai

thats a steal !!!!!!

[mania]

thats a steal !!!!!!

Yeah not much more than a scooter & that was a good year too.

[pokerkid]

thats a steal !!!!!!

Yeah not much more than a scooter & that was a good year too.

get it quick krs1, you know you want one...

[Gomyway]

You have to allow for speedo optimism. I would say 168 is about 155 or less. To get 168 real you'll need about 32 hp. If you can measure with GPS i can update my formula

Depending on valve lift you could use other Honda's double valve springs for bikes with power at higher RPMs.

Please don't forget that when your springs are stiffer it takes more power to move the valves, so the result could be that the engine doesn't like to rev as easy as before.

Working on springs of the valves is already the high level of tuning an engine.

I'd read many test from german motorcyclist about the Honda CBR 250 (before I bought the Ninja I've been interested in the CBR) and they all said or say that reving higher then 9000 rpm is very tough and not worth it.

Also keep in mind that the Ninja 250 with her 11000 rpm power peak doesn't make sense to rev higher then 12000 bc at that point the power is dropping down.

Only an Italian company (Scuderia Platini) in their racing bikes make her reving up to 12700 rpm (peak is at 12418 rpm) but they'd also install 30 mm throttles instead of 28mm oem plus other cams and many more stuff.

[KRS1]

thats a steal !!!!!!

Yeah not much more than a scooter & that was a good year too.

get it quick krs1, you know you want one...

LOL...yeah its been in the back of my mind.

Im going to make a muffler (yes make one myself- ** insert laughter here) and go up 2mm on the second section of the downpipe and see what happens.

Just feel like tinkering right now.

[yankee99]

Before you make any changes do a dyno so you have a baseline. post the results here please

[mania]

Before you make any changes do a dyno so you have a baseline. post the results here please

Yeah it is a Honda so BW Chiangmai will actually do one.

[KRS1]

You have to allow for speedo optimism. I would say 168 is about 155 or less. To get 168 real you'll need about 32 hp. If you can measure with GPS i can update my formula

Depending on valve lift you could use other Honda's double valve springs for bikes with power at higher RPMs.

Please don't forget that when your springs are stiffer it takes more power to move the valves, so the result could be that the engine doesn't like to rev as easy as before.

Working on springs of the valves is already the high level of tuning an engine.

I'd read many test from german motorcyclist about the Honda CBR 250 (before I bought the Ninja I've been interested in the CBR) and they all said or say that reving higher then 9000 rpm is very tough and not worth it.

Also keep in mind that the Ninja 250 with her 11000 rpm power peak doesn't make sense to rev higher then 12000 bc at that point the power is dropping down.

Only an Italian company (Scuderia Platini) in their racing bikes make her reving up to 12700 rpm (peak is at 12418 rpm) but they'd also install 30 mm throttles instead of 28mm oem plus other cams and many more stuff.

revving past 9k only gets hard when your in 6th gear.

all other gears it will blow right past 9k.

[KRS1]

Before you make any changes do a dyno so you have a baseline. post the results here please

Yeah it is a Honda so BW Chiangmai will actually do one.

is it free?

[mania]

Before you make any changes do a dyno so you have a baseline. post the results here please

Yeah it is a Honda so BW Chiangmai will actually do one.

is it free?

You know when I talked to them on the phone once the guy actually told me it was free for 1 pull ( Honda )

Of course when I showed up & explained I had a Ninja they would not do it for any price which

I thought was really odd

[KRS1]

Before you make any changes do a dyno so you have a baseline. post the results here please

Yeah it is a Honda so BW Chiangmai will actually do one.

is it free?

You know when I talked to them on the phone once the guy actually told me it was free for 1 pull ( Honda )

Of course when I showed up & explained I had a Ninja they would not do it for any price which

I thought was really odd

alright i'll give them a try and see what they say.

I guess i should mention that i installed ninja 250 mirrors on my bike, dont know if it had any effects. But the reason i did this was to eliminate one point of wind resistance, the mirrors are now directly in front of my hands. Im mentioning this because im also going to be working on making the bike more aerodynamic also, as well as losing some weight. So change in power wont be the only factor if it gets faster.

[pokerkid]

no need for all that, just put on a pair of speedo's and ly on the bike, you be popular with the german ladies as well.