cbr250rr modifications

[BladeBoy]

Is there any modifications a can do to my mc22 to give it more power? if i opened up the airbox slightly and put air intake into the box would it do anything or just make it run to lean? i think they squeeze all the power they can out of these little motors but there must be something else i can do. its got a smaller front sprocket and an aftermarket can already.

[vtec]

You serious about mods. Ask the guys at www.cr-x.org/cbr250/

In reality, I always raced the mc22 as standard and I won a lot of races on them. Even in Aussie where people were allowed mods and there were plenty of major mods done. The best mod you can do is to your own riding ability, get some track time.

If you play with the air flow ala exhaust/intake free flowing, you'll need to play with the jetting too, which is all too much of a pain in the arse in my opinion. They run awesome from standard, and are very reliable don't fuck with them.

[BladeBoy]

oh yea. sweet as thanks for your input. yea its a mint runner aye and faster than any of my mates 250s and realible as hell. just want a bit more out of it aye. i can get my full now so might be easier to just upgrade.

[The Pastor]

yeah mate you can do lots.

You can rip the aribox off completely put in a full exhaust system and wack 145 main jets in ur carb and get it balanced it'll run pretty damn sweet and sound SOOOOOOOOOOOOOO good.

You can remove the 180km/hr limiter really easily, its just cutting a wire and adding in a resistor.

then you can play with the cam etc

you wont gain mega hp out of it, i think you'd only be able to get 40-45 at the wheel max.

unless you run a nitro mix in ur petrol ;)

[SS90]

yeah mate you can do lots.



you wont gain mega hp out of it, i think you'd only be able to get 40-45 at the wheel max.



hmmm, dunno about 40-45 hp there mate.

I have operated dyno's for the last 8 years or so, and the most I have seen on any 250 I.L.F is 35 HP. Most are 32HP

45 HP is quite a bit!

a good road going I.L.F 400 will only make 60HP, most are around 55HP

[The Pastor]

hmmm, dunno about 40-45 hp there mate.

I have operated dyno's for the last 8 years or so, and the most I have seen on any 250 I.L.F is 35 HP. Most are 32HP

45 HP is quite a bit!

a good road going I.L.F 400 will only make 60HP, most are around 55HP
i reckon 10 extra hp is possiable with mods?

[The Pastor]

Is there any modifications a can do to my mc22 to give it more power? if i opened up the airbox slightly and put air intake into the box would it do anything or just make it run to lean? i think they squeeze all the power they can out of these little motors but there must be something else i can do. its got a smaller front sprocket and an aftermarket can already.
http://www.trademe.co.nz/Browse/Listing.aspx?id=246956229

stack load of mc22 parts forsale

[SMOKEU]

Get a turbo for it.

[Blackshear]

RE: Mr.Dyno reporting 35hp L-4's, did the manufacturers take the HP readings from the crank?

[gatch]

a good road going I.L.F 400 will only make 60HP, most are around 55HP

how bout a v4 ?

[sil3nt]

RE: Mr.Dyno reporting 35hp L-4's, did the manufacturers take the HP readings from the crank?Fairly sure they all do unless otherwise stated.

[McWild]

A friend's CBR250RR made 44RWHP when it was dyno'd about a month ago.

Not saying there couldn't have been dyno error, but the dyno seemed about right with the other bikes on it.
They were an '03 GSXR600 making 103 and a Bandit 250 making 35ish but it was running averagely.


You could always just take off the can entirely, makes quite a sound from personal experience!

[SS90]

A friend's CBR250RR made 44RWHP when it was dyno'd about a month ago.

Not saying there couldn't have been dyno error, but the dyno seemed about right with the other bikes on it.
They were an '03 GSXR600 making 103 and a Bandit 250 making 35ish but it was running averagely.


You could always just take off the can entirely, makes quite a sound from personal experience!

Like I say, I have never seen more than 35HP from an ILF 250.

You can argue about results till your blue in the face, and at the end of the day it is all Academic.

Do you have a printout available for your mates 44 HP run?

I have just Googled for the last 20 mins, and all I have come up with is this......

It always impressed me that the CBR's (later model ones) where more powerful than the ZXR's (I expected the other way round), but like I say, I never saw more than 35 HP.

I guess it is down to the model though, and obviously I have not "seen them all", if anyone can furnish a dyno run for a CBR250 I would love too see it!

44Hp is quite a bit!

Although, I do remember that some later models revved to something like 20K, that's quite a bit, but at revs like that you suffer down low......

[CookMySock]

Tyres and suspension mate.

Steve

[McWild]

Like I say, I have never seen more than 35HP from an ILF 250.

You can argue about results till your blue in the face, and at the end of the day it is all Academic.

Do you have a printout available for your mates 44 HP run?

I have just Googled for the last 20 mins, and all I have come up with is this......

It always impressed me that the CBR's (later model ones) where more powerful than the ZXR's (I expected the other way round), but like I say, I never saw more than 35 HP.

I guess it is down to the model though, and obviously I have not "seen them all", if anyone can furnish a dyno run for a CBR250 I would love too see it!

44Hp is quite a bit!

Although, I do remember that some later models revved to something like 20K, that's quite a bit, but at revs like that you suffer down low......

I can ask him to take a photo of it or scan it and post it up (or I will) when I get the chance. I think it would be interesting to get it run at a different place as well but really it's just not worth the money for a simple comparison.
I have to say that it does feel like it has a bit more pull than the last MC19 I rode.

[mossy1200]

A 15-20% gain in top end horspower is going to cost you head work ,cams,higher compression and flatslides and pods.Are you prepared to put in 4grand to get 10hp?
Bearing in mind this will also cost you mid range hp and torque.

Cheeper to get bigger bike or sell and buy rs250 aprilia if your on licence restriction.Maybe get a race bike and live with the road power you already have.

[Dave-]

I'll vouch for the 44RWHP claim

I've seen the print out!

BUT eliots gixxer did only score 103 when it should be up around 115, however I think jeff may have had it dyno tuned to run 1/4 mile, as I remember he use to do drags.

[Bangbug]

you can be brave and advance the timing 3 degrees and run it forever on 98.
They retarded the timing through the midrange from the factory.
NOBODY can make an after market ICU for them cuz they rev too hard, lol.
Give the carbs an overhaul. (take it to a tuner) (ok... a good one)
Give the suspension an overhaul.
Buy some STICKY tyres.
Buy some QMOTO gear.
Buy some brave pills :)

[Spyke]

I saw on the net a 250 bandit with turbo making alot of hp did a 12. something down the quater.


I saw that on the net though

[SS90]

I saw on the net a 250 bandit with turbo making alot of hp did a 12. something down the quater.


I saw that on the net though

Then it MUST be true.

[The Pastor]

you can be brave and advance the timing 3 degrees and run it forever on 98.


Care to explain this a bit better? What dose advancing the timing do? any other mods that have to to with it? what improvement does it offer?

Thanks,
Rm

[Dave-]

Care to explain this a bit better? What dose advancing the timing do? any other mods that have to to with it? what improvement does it offer?

Thanks,
Rm

fuel takes time to ignite and start expanding.

when the spark fires the expansion isn't instant, there's a measurable number of milliseconds before it starts happening.

iirc (and feel free to correct me if im wrong) factory bikes are tuned to light the spark when the piston is at its highest point, so when the fuel starts expanding the piston has started going down already, this loses valuable time that the piston could be pushed down, instead it's just bring pulled down thanks to the crank.

what you can do is make it so that the spark fires before the piston gets to its highest point, and time it (hence ignition timing) so that the gas starts expanding the instant the piston is at its highest point.

however this will lead to more engine wear, if you fuck it up and expand before the piston reaches it's highest point you'll blow your bearings, you'll also want to use a very fast burning fuel (98 octane)

do what you want, but if you blow up your bike, not my fault.

[vtec]

Hmm, you are mostly right, but I'm pretty sure that higher octane is slower burning which is why you need to use it when you have a lot of timing advance, so even if it explodes before TDC it is slightly slower to start pushing the piston down.

If you don't want to fuck with the timing then just do what I do run it on 91 octane as that is what the timing is set up for. There probably is a bit of power to be gained by doing the 3 degree advance and running 98, but it comes with a big risk. I would probably be more inclined to do a 1 degree advance and try running it on 98 and 91 to see which one behaves better.

These engines going extremely fast actually suit the lower octane and have a designed retard to run it safely, as it explodes quicker than 98.

I can be sure there will be arguments about this.

i'm sticking with track time and good tyres. Just make sure the fork oil is relatively fresh too.

P.S. Thought of another way to put the advance problem into words. You can only tune the advance to suit one part of the rev range if you don't have Honda's VTEC system or Toyotas VVT... or any VVT system, so if you tune it to suit the most powerful part of the rev range, then you will have issues with detonation at lower revs (a bad thing). I vote for leave it the hell alone and get a faster bike if you want more power. TheCBR250RR is the best 250 IL4 largely because of its reliability, change anything more than flow and fueling and I guarantee you will lose reliability unless it is done by an excellent engineer.

[BladeBoy]

thanks for all of your input guys. i think ill just upgrade aye. might be easier. moneys a bit tight but i see a might be able to sell mine and get a vfr400 for not much more money . do they have much more power? id prefer a cbr600 or r6 but to expensive at the mo with baby number 2 on the way.

[mossy1200]

thanks for all of your input guys. i think ill just upgrade aye. might be easier. moneys a bit tight but i see a might be able to sell mine and get a vfr400 for not much more money . do they have much more power? id prefer a cbr600 or r6 but to expensive at the mo with baby number 2 on the way.

Vfr is nice bike.Not huge power increase top end but lots more torque through the whole range.250s sell for good money if your not rushing a sale and not big price differnce to a 400.If you want lots more power then 600 would be the go but a good 600 is going to cost 5grand upwards.Most older 600s are flogged and worn out unless you get lucky with your search.

[quickbuck]

Most older 600s are flogged and worn out unless you get lucky with your search.

Ahemmmm.. I wouldn't say it is flogged out.... much.....
Still does rapid times arounf Manfeild..
Then again, check vtec's first post for "Tuning Advise"....

[mossy1200]

Ahemmmm.. I wouldn't say it is flogged out.... much.....
Still does rapid times arounf Manfeild..
Then again, check vtec's first post for "Tuning Advise"....

Unlike 99% of 600 owners of late 80s early 90s bike you would know where the sump plug is and the oil you give it is called an oil change not top up.

[.produKt]

De-baffling the airbox is something i've heard. Anyone care to testify?

[ac3_snow]

Hey mate check this out re your airbox
http://www.cbr250.com/cbr250/forum/topic.asp?TOPIC_ID=26849

all Iv done is replace my filter with foam (uni foam from most mtrbike shops-remember foam oil too) and noticed a slight improvement (then again old paper 1 was filthy). didnt reali have the time or funds to get right in there with new jets and all.
Interesting looking at the dyno sheet someone showed previously tho makes me wanna strip my carbs and clean etc....
I have heard that the headers where sumwhat restricitve too, but for the cost of new ones is it reali worth it?
that cbr250.com site has some wicked tech posts and tips (saved me when i stripped my brakes down) shows you how to do fork oil and stiffen them up etc..

[roadracingoldfart]

Bugger all the hard work tuning a 250 . Put a 400 engine in and be done with it .

[HDTboy]

I posted a guide to modifying these bikes on here about 5 years ago. SEARCH.
@RROF: Flag the 400 motor, get a 2T 500 (http://www.twostrokeshop.com/Aprilia_RS500_2008.htm). But then you're still stuck with a 20 year old chassis and brakes designed for slowing down a sewing machine motor.
@VTEC: You may be getting confused between cam timing and ignition timing, altering either may give you a power increase, or may decrease power or destroy the engine if you get it very wrong. The process is called tuning, and having a dyno makes it a less difficult job.

[.produKt]

Hey mate check this out re your airbox
http://www.cbr250.com/cbr250/forum/topic.asp?TOPIC_ID=26849

all Iv done is replace my filter with foam (uni foam from most mtrbike shops-remember foam oil too) and noticed a slight improvement (then again old paper 1 was filthy). didnt reali have the time or funds to get right in there with new jets and all.
Interesting looking at the dyno sheet someone showed previously tho makes me wanna strip my carbs and clean etc....
I have heard that the headers where sumwhat restricitve too, but for the cost of new ones is it reali worth it?
that cbr250.com site has some wicked tech posts and tips (saved me when i stripped my brakes down) shows you how to do fork oil and stiffen them up etc..

Ignore the angry buggers above. I couldn't find that so called guide and it's an offence to mislead about engine capacity etc etc blah

"I have heard that the headers where sumwhat restricitve too, but for the cost of new ones is it reali worth it?" I plan on doing just that, Buying an entire exhaust system from RM and i will be doing a Dyno test video before and after :)

[lankyman]

Is there any modifications a can do to my mc22 to give it more power? if i opened up the airbox slightly and put air intake into the box would it do anything or just make it run to lean? i think they squeeze all the power they can out of these little motors but there must be something else i can do. its got a smaller front sprocket and an aftermarket can already.

Upgarde....I suggest the NC30 VFR400. Handles like an MC22 with nearly twice the pep

[HDTboy]

Ignore the angry buggers above.

Fuck you, don't be a lazy cunt. Search (http://www.kiwibiker.co.nz/forums/showthread.php/16580-Hotting-up-a-CBR250RR)

[.produKt]

Yay! A single page thread with a dead primary URL


...

[ac3_snow]

lol hopefully this so called guide will work this time
http://motorbikecity.com/cbr250/forum/topic.asp?TOPIC_ID=26849

[.produKt]

lol hopefully this so called guide will work this time
http://motorbikecity.com/cbr250/forum/topic.asp?TOPIC_ID=26849

Yea did work. But all images are moved and\or deleted, so nohope of doing it myself.

I have now got a shiny new rear can and headers for the cbr. Oversized and sounds great.
Needs to be tuned tho. theres a horrid deadspot around 8k rpm which seams less a dead spot when the bike is thoroughly warm.
Powerband rpm's (12.000 - 14,500) seems to charge a lot harder but that could be a perseption thing due to the dead spot.

[The Pastor]

Yea did work. But all images are moved and\or deleted, so nohope of doing it myself.

I have now got a shiny new rear can and headers for the cbr. Oversized and sounds great.
Needs to be tuned tho. theres a horrid deadspot around 8k rpm which seams less a dead spot when the bike is thoroughly warm.
Powerband rpm's (12.000 - 14,500) seems to charge a lot harder but that could be a perseption thing due to the dead spot.

(just keep it above 8krpm)

[.produKt]

Heh. A smartarsed yet correct reply :P

Quick off topic question. Did you notice that the larger exhaust diameter fouls the movement of the rear brake lever?

[The Pastor]

Heh. A smartarsed yet correct reply :P

Quick off topic question. Did you notice that the larger exhaust diameter fouls the movement of the rear brake lever?

no, it was custom made so everything should be working great, post up a picture?

Also check the bolts for the slipon are not touching the swingarm, they will gorge it a bit. hard to describe

[.produKt]

Will post up a pic tonight when i can borrow a Camera.

Bolts for the slip-on are a-ok. Guys who mounted it made sure the nut and bolt of the clamp are rotated to the top of the slipon section. They didn't notice the brake lever movement foul tho =\, which i find particularly annoying.
edit: Fouls to roughly 1/4 braking effort. Annoyied but not concerned as exhaust moves a bit with force on the brakes so can get more out of it if need be

[imdying]

I know a guy who can fix it for you if you get stuck.

[.produKt]

I know a guy who can fix it for you if you get stuck.

Yea, who's that?
I'm half expecting a smart answer :P

[98tls]

Yea, who's that?
I'm half expecting a smart answer :P

Na mate,methinks he can get it sorted.

[.produKt]

Will show the problem shortly. I'm dwelling on it now and i wonder if it'll pass a wof, for which it is due =\

[imdying]

Yea, who's that?
I'm half expecting a smart answer :PSame guy that did the welding on the SVs exhaust. TBH anywhere should be able to correct that, I just find it easier going to someone who has done before the sort of work I need done... YMMV

[scracha]

I've got a lovely CBR400 motor you could just shove in there. Come to think of it, I've got 2. You can't beat cubes.

[PirateJafa]

I've got a lovely CBR400 motor you could just shove in there. Come to think of it, I've got 2. You can't beat cubes.

:niceone: There is no replacement for displacement. Says the guy who has just gone from 130hp to 35hp...

[.produKt]

Hmm a cibby400 motor.
Gotta VFR rear swingarm too? might slap that on also ....

[gatch]

:niceone: There is no replacement for displacement. Says the guy who has just gone from 130hp to 35hp...

Those pom bastids in pom land are gunning for 100hp out of their vfr/rvf450.

That's cool.

[ducatilover]

Those pom bastids in pom land are gunning for 100hp out of their vfr/rvf450.

That's cool.

Ferkin ridonculous!!!!!! :drinkup::woohoo: