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Discussion Starter #1
Hey guys,

Been a long time rider with many bikes under the belt. Scored a MC22 blade last week and have been doing the little thing up. Was wondering, if anyone here can point me in the direction on information about removing the rev limiter and the speed limiter for track work? All short of a full piggy back ecu.

Any help would be most apprpeciated.

Cheers

Dr Karl
 
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1. Pacey?
2. Eclipze had a writeup of putting a 3.3ohm resistor between the orange wire and the...... on the ecu and cutting the orange, which delivered the correct signal and fooled the ecu into not limiting speed.
 

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Speed restrictor removal:
http://cr-xorg.readyhosting.com/cbr250/forum/topic.asp?TOPIC_ID=19547

Rev limiter removal I believe requires a new CDI.

Justin.
 

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Dr Karl said:
its more the rev limiter im looking for though.
This has WIN written all over it! :headbang:

I predict much valve float in your future, young padwan. Please post pics of the result.
 

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Dr Karl said:
Pacey? Hmm interesting, its more the rev limiter im looking for though.
I can't really invisigage what you'd be after removing or lifting the rev limiter for, its already 5000RPM after the bike has developed peak power, so making it a bit further won't make the bike any faster and will increase the risk of engine damage. In fact if you pushed it to redline even as is you'd probably end up slower than surfing around peak power.
 

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sir.b said:
Speed restrictor removal:
http://cr-xorg.readyhosting.com/cbr250/forum/topic.asp?TOPIC_ID=19547

Rev limiter removal I believe requires a new CDI.

Justin.
pretty sure you only have to connect 2 terminals... thats assuming they mean the speed limiter, no the rev limiter
 

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Drew: Overrev can be useful on the track. Hitting the limiter a little before your braking marker is annoying and some over rev means you can stay on power right to the marker. I'm not in any way recommending it or saying it's safe however!

Justin.[hr]
smiley_666 said:
pretty sure you only have to connect 2 terminals... thats assuming they mean the speed limiter, no the rev limiter
Did you click the link I posted? :huh:

Justin.
 

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sir.b said:
Drew: Overrev can be useful on the track. Hitting the limiter a little before your braking marker is annoying and some over rev means you can stay on power right to the marker. I'm not in any way recommending it or saying it's safe however!

Justin.[hr]
smiley_666 said:
pretty sure you only have to connect 2 terminals... thats assuming they mean the speed limiter, no the rev limiter
Did you click the link I posted? :huh:

Justin.
I realised that, but the CBR250 has to be the bike with one of the largest overrevs on the market, I think peak power is somewhere around 14.5krpm and the redlline is at 19krpm... I mean on a 600 or a liter you'll get 1000-2000RPM maybe...
 

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If these bikes could rev higher, then Honda would have done so to be on top of the peak RPM battle they were having in Japan at the time. Going higher... I suspect you might start running into mechanical problems and compromise the reliability.

I never found that I needed to pre-select a gear that low that I'd be close to the limiter on corner entry. If it's a problem for you, pick a taller gear and use the clutch to pick up the RPM and pull the torque out until your back into normal power band.
 

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FAR OUT!

This question has come up a million times and you guys still cant answer it.

http://www.ignitech.cz/english/aindex.htm

This is what you need.

Also if I were you, I would move the exhaust collector closer to the engine, use open carbs (or if you are worried, use a unifilter and take off the snorkle) and remap the ignition for power higher up in the rpm range.

I would also chose gearing appropriate for the track you want to ride on... so invest in some sprokets.

I have also read that honda had raced this engine up to 22k. The piston speed is actualy low in comparison with modern bikes.
 

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bloody aussie got his up to around 21.5k

from memory he was using a digital tacho, as it is more accurate
 

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Matt said:
bloody aussie got his up to around 21.5k

from memory he was using a digital tacho, as it is more accurate
Do you know what tacho he was using? I have been looking for one in abit of my spare time... never really found anything.

I was thinking about using ignitechs software... but that isn't good for a tacho if a full time mini laptop is needed.

the accuracy of the stock tacho is terrible.
 

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Humbug said:
FAR OUT!

This question has come up a million times and you guys still cant answer it.

http://www.ignitech.cz/english/aindex.htm

This is what you need.

Also if I were you, I would move the exhaust collector closer to the engine, use open carbs (or if you are worried, use a unifilter and take off the snorkle) and remap the ignition for power higher up in the rpm range.

I would also chose gearing appropriate for the track you want to ride on... so invest in some sprokets.

I have also read that honda had raced this engine up to 22k. The piston speed is actualy low in comparison with modern bikes.
I think you'd find that the main problem is going to be cams and valve springs, rather than anything else. It produces peak power around there because thats where the cams are tuned for etc. You might be able to move the peak torque around by playing with exhaust tuning, but you can't move peak power much with intake/exhaust tuning IMHO.
 

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agreed. you can add cams to the wishlist.

as for valve springs, you can get hollowed titanium valves and brass seats for maybe $2k
 

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Discussion Starter #19
Hey guys thanks all for the postings. Im not concerned about engineering, i build bikes, and have been riding for 18odd years. Valves, cams, ports ets, all will be in a days test and tune for me. This bike is just a bit of fun, sure alot cheaper than working on the ducacti or ninja i tells ya.

Cheers again guys
 
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