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Good man ! Sticking with the stock injector?

Also if you contact AKUNAR directly their prices are about $30+ cheaper and they have many other Grom/MSX parts not listed... eBay fees are killing the small guys :(
 

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Hi

I spotted these yesterday too on USA

The price he gave me direct including UK shipping was $191

However the TB is the Thai one and I am not sure if it has the idle valve fitted or provision for you to fit it - but not sure if that's an issue for USA guys

I asked the question and they do not know.

The increased TB diameter should give 13% more air - which probably will be enough

I know our Pioneer SnakeIBF is looking at fitting the CBR125 TB and a Power commander!!

Wish you both luck and let us know how it goes
 

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I talked to a guy at bazzaz last week and on Monday to a guy from Dynoresearch. Bazzaz said they were talking with Yoshimura to develop some kind of controller for the Grom, but the guy I talked to didn't seem to think they got very far with it. Dynoresearch (the company that makes the Power Commander) say they are working on making a controller. They also said they were having some problems with the 1 wire O2 sensor and were working on a solution. They would not give me any kind of timeline and I didn't ask, but I'm guessing they will have something this winter. I like the idea of the PCV on the grom, I do a lot of engine mods and I like the ability to go into a program and tweak the maps at will.

I bought a 30mm throttle body from a CBR 125 cheap off ebay hoping the TPS, IAC and injector would have the same plug. They do not, the grom has a 3 pin TPS. One pin is the VCC or reference 5v, the other is the signal and the third is the ground. On the CBR it has 5 pins and When I removed it, it appears they integrated the IAT into the assembly, hence the extra 2 pins. It may work, but I need to compare ohm readings from the potentiometer on the sensor to see if the pots have the same ohm rating.

The Injector plug is different, but it looks like the grom injector should fit in there no problem and the stock fuel line as well.

The IAC also has a slightly different plug. I bought a cheap wiring harness from ebay and I believe it's possible to make it work if I can find a wiring diagram that shows me the which pin is what on the CBR 125. I also had a mounting flange from another build that fits perfectly and mounts directly to the head. This might be a fairly simple hookup once I find the wiring diagram for the CBR 125.

I'm definitely interested to see how this box you bought works out. I think it's very similar to the one Yuminashi has, the casing looks the same. Do you have an A/F meter with a wide band 02 sensor so you can adjust it correctly or are you planning on using a dyno?
 

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I'm definitely interested to see how this box you bought works out. I think it's very similar to the one Yuminashi has, the casing looks the same. Do you have an A/F meter with a wide band 02 sensor so you can adjust it correctly or are you planning on using a dyno?
How does a wide band 02 sensor help dial this in? I can see how a dyno will give you readouts that you adjust to, but what is a wide band 02 sensor?
 

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How does a wide band 02 sensor help dial this in? I can see how a dyno will give you readouts that you adjust to, but what is a wide band 02 sensor?
as far as i know, with a wide band o2 sensor, you can constantly read your A/F, air fuel ratio, so you know what rpm to add or remove fuel.
 

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Just check out the dynojet auto tune. It can be used in conjunction with the PCV and allows on the fly adjustments. It reads the A/F ratio using the O2 sensor and adjusts fuel trim based upon how far outside the range the engine is running from the preset map value at that RPM. For example if the value is set at 13.2:1 at 4000RPM and the engine is running too lean, say 14.7:1 based on what the O2 is reading the ECU will correct it by increasing PW on the injector to richen the mixture. A wide band sensor can read a wider range of mixtures than a narrow band. This is ok for a stock system, but if you start drastically changing your engine such as a head with larger valves or a big bore kit you run the risk of running outside what the stock 02 sensor is capable of reading. When this happens the ECU may thing there is a fault and will default to open loop.

Actually with the PCV on the CBR 125 they tricked the computer by installing a resistor in line with the O2 sensor so it didn't set off a CEL, but it did allow the system to run open loop so the PCV could control the PWM instead of the computer. That's what they told me anyway.
 

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You can actually buy generic meters with a digital readout that will tell you in real time your A/F ratio. They come with the Wide Band O2 Sensor and usually a bung you can weld on to your pipe.
a digital gauge that you can mount
Thanks.

Man, just when I thought I was getting good a jetting carbs on the little motors......
 

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Just check out the dynojet auto tune. It can be used in conjunction with the PCV and allows on the fly adjustments. It reads the A/F ratio using the O2 sensor and adjusts fuel trim based upon how far outside the range the engine is running from the preset map value at that RPM. For example if the value is set at 13.2:1 at 4000RPM and the engine is running too lean, say 14.7:1 based on what the O2 is reading the ECU will correct it by increasing PW on the injector to richen the mixture. A wide band sensor can read a wider range of mixtures than a narrow band. This is ok for a stock system, but if you start drastically changing your engine such as a head with larger valves or a big bore kit you run the risk of running outside what the stock 02 sensor is capable of reading. When this happens the ECU may thing there is a fault and will default to open loop.

Actually with the PCV on the CBR 125 they tricked the computer by installing a resistor in line with the O2 sensor so it didn't set off a CEL, but it did allow the system to run open loop so the PCV could control the PWM instead of the computer. That's what they told me anyway.
im kinda confused, the grom has a o2 sensor? or they are trying to instal a one wire o2?
 

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Wide band is 0-5volts, normal band is 0-1volt

Wide band has higher resolution

I have a wide band that data logs and has an input for a TPS and engine rpm and a few other things so that you can sit at the pc and review what happened which for a bike is the safest way to do it. My car one I can read on a lap top real time while someone else drives.

One thing to consider is the diameter of the head pipe on the Grom and make sure you don't end up with a sensor that completely blocks the pipe.

Back in the Day, I ran a high end data logger on my dyno and had a O2 sensor in each head pipe. But that was when I was picky and cared what each cylinder was doing. Now I just want to pin it and attack with violence of action on my Grom
 

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Discussion Starter · #20 ·
I'm pretty sure the box is the same as Yuminashi - I will use dyno if necessary
I do not think it should be a big deal to set the box up right - as long as you check the engine temperature and spark plug color - while Road testing
currently with 150 kit - the venturi in the original throttle body is way too small - while tuning at the rest of the engine
good news is - the parts is already shippet from thailand
 
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