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...because every day is MotoGP day when you own a CBR 125r...
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PostPosted: Mon Jan 05, 2015 5:28 am 
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Performance Pack

Joined: Tue Mar 25, 2014 3:21 pm
Posts: 35
Australia
So somewhere I saw someone make a passing reference to changing a resistor to get more fuel into the engine; I asked for more info but it was long ago and he couldn't recall - but luckily, Mr Google could:

http://www.ozbucketracing.com/buildingcommuterlite.html

Given that this is a guide used by folk actively racing their bikes, I'm inclined to believe that they have found some extra power: too bad I don't have a furry clue what they're talking about!
And then I found this interchange:

https://www.perthstreetbikes.com/forum/ ... p?t=112693

Anyone with a clue care to examine and discuss?


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PostPosted: Mon Jan 05, 2015 11:24 am 
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Racing ECU (!!)
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Location: Parksville, BC, Canada
Canada
It's a cheeezy way to richen up the fuel mixture :laugh:

Think about a carburetor - when the engine is cold the choke comes on, the choke plate closes up and reduces the amount of air coming into the engine. By effect, this makes it richer. The engine needs to be richer when it's cold.

So with EFI you need to do the same thing. The computer (ECU) needs to know if it's cold. The way it determines this is primarily through the coolant temperature sensor. The secondary way it changes air/fuel ratio is through the IAT (Intake Air Temperature) sensor.

But, the main way is through the coolant temperature sensor. The coolant temperature sensor is a NTC resistor. This means it changes resistance depending on temperature. The ECU has an algorithm built in that says, 'if resistance =x then I'm cold, if resistance =y then I'm warm and if resistance =z then I'm hot' :laugh:

Based on the resistance of that sensor, it checks it's program and makes the fuel richer or leaner depending on whether it thinks the engine is cold or hot. It does this by leaving the injector open longer which lets more fuel in.

So if you install a resistor in-line on that sensor then it will cause the ECU to always think it's cold. If the ECU always thinks it's cold it's going to always richen up the Air Fuel mixture.

It really is a hack. The commonly used device to do this more 'properly' is a Power Commander which is a piggy-back ECU that sits between the stock computer and the wiring harness. It works much the same way (a hack) by intercepting the injector signals from the stock ECU and then altering them as you see fit. This does the same thing but in a better way in that you can adjust it over the full range of operation.

When you really boil it down to basics you're fooling (fueling? :laugh: ) the ECU into leaving the choke on - on a permanent basis :laugh:

You can do this, it's certainly not expensive, but you have to cut your wires and experiment. Another way to skin the cat is to install the injector from a CBR150r. This injector flows more fuel then the CBR125r injector. I've done this and it's really remarkable how much power it makes on the high RPM side. The stock ECU is designed to use the 125cc injector so it just operates as if it has one. When the engine is hot it uses the oxygen sensor to adjust the fueling so it will trim the open time of the injector as required. However, when the throttle is wide open the stock ECU goes open-loop and ignores that sensor and defaults back to 'max performance' mode and the bike really flies.

I have one here that I will be putting up for sale at some point. It's new OEM with only about 1 month of runtime on it. If you want to try it, let me know, otherwise I'll be putting it up pretty soon in the store. They're hard to get. I need a bigger one yet as I have a need for more fuel flow during nitrous operations :bike:

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PostPosted: Wed Jan 07, 2015 12:35 am 
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Performance Pack

Joined: Fri Oct 24, 2014 6:21 am
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Location: Horwich
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I'd be interested in buying your cbr150 injector if/when it goes for sale. I've been looking everywhere and can't find one at all! So if you're going to be selling one I'd definitely be interested price depending as I have no idea how much they are. Feel free to private message me if you have an idea how much you'd be selling for.

Alex

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PostPosted: Wed Jan 07, 2015 12:44 am 
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Racing ECU (!!)
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Location: Parksville, BC, Canada
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Will do :top:

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cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...


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PostPosted: Sat Feb 04, 2017 2:09 pm 
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Joined: Fri May 27, 2016 4:39 am
Posts: 11
Norway
Hi!
Do you still have the CBR150R injector? If not, where can I get one? I would love to add one ontop of the performance pack and my open exhaust. The cylinder has also been bored slightly up to remove big scratches so more fuel is definetly needed.


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PostPosted: Tue May 23, 2017 5:27 pm 
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Joined: Fri Jul 29, 2016 5:37 am
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http://www.honda-cbr-125.com/cbr_125_30 ... e_body.php

Scroll down to the bottom of the page


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PostPosted: Wed May 24, 2017 6:26 am 
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Clutch Kit
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Have you bought from there before?
Between the shoddy English and direct PayPal transfers, I'm a bit leery.

But they do have a decent selection of parts...

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2008 CBR 125: Performance Pack; Dual Headlight Mod; Shortened Front Indicators; Shad SH-40 Top Box; 80/90 front, 120/80 rear


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PostPosted: Wed May 24, 2017 7:30 am 
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Joined: Fri Jul 29, 2016 5:37 am
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No I haven't.

The imperfect English is understandable, but yes, I share your reservations. He does sell through ebay since 2010 and I see that his feedback rating is 100%

http://www.ebay.ca/usr/asiatradeinc-gmail

I'm very tempted to get a camshaft from him


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PostPosted: Wed May 24, 2017 7:43 am 
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Clutch Kit
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Thanks for the eBay link, that eliminates all my concerns! At least there's some buyer protection through eBay.
He must be one of the last/only places left to get 125 parts.

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- Wyatt Avery
2008 CBR 125: Performance Pack; Dual Headlight Mod; Shortened Front Indicators; Shad SH-40 Top Box; 80/90 front, 120/80 rear


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PostPosted: Wed May 24, 2017 7:52 am 
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Joined: Fri Jul 29, 2016 5:37 am
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It doesn't look like he has the injector listed, but you could ask him to sell it to you on ebay.

I'm actually starting to think I should get one of those too. I've ordered a EJK fuel tuner to adjust my fuel map for a new cam, but it might be just as effective to change the injector instead. Increased fuel at open loop only. Hmmm


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