Guys, I just bagged a 1.5k on odo 2013 CBR250r from a friend of mine. It is awesome in all terms but the devil inside me is asking for more. I am used to riding all my bikes with a free flow exhaust and the absence the of it in the CBR is killing the fun. While browsing around I found this, CBR 250 R 2011-2013 GP Extreme [EX-00405] - $112.00. I am not sure how reliable this Dan Moto exhausts are but the finish seems pretty decent. Need your advice.

Nice discussion this. :PGM-FI is an n-alpha mapped injection system. That means the basic variables are the engine speed (n) and the throttle angle (alpha). Based mainly on these two measurements, the system looks to its fuel mapping for the fuel delivery figure corresponding to the n and alpha of the moment.So, let us assume that we're making use of engine braking downhill without the application of throttle. This means that the alpha component is ZERO. Hence, there should be no fuel being delivered for combustion. If this is true, why coast with the clutch disengaged?

Any suggestion on this guys?

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Correct, @icemang you forgot to consider the TPS. Though there are different types of TPS, but in FI engines they do give feed back to the ECU.

Would set you back by ~10k including shipping. Performance boost may be by 2 ponies extra. If you think its worth, you may go for it.
A friend of mine got CBR250R 11-12: Yoshimura R-77J CF tip-SS Slip-on - 25,999.00.. for 25k rupees, but has reverted back to stock as he says he gets tired on long trips due to the noisy muffler!

EDIT - 10k OTOH can fetch you lovely gear bro.

Correct, @icemang you forgot to consider the TPS. Though there are different types of TPS, but in FI engines they do give feed back to the ECU.

Nice discussion this.

If we go through - How it Works: Programmed Fuel Injection (PGM-FI) Technology - Experience Powersports - Honda Powersports, we find the following portion that says:

PGM-FI is an n-alpha mapped injection system. That means the basic variables are the engine speed (n) and the throttle angle (alpha). Based mainly on these two measurements, the system looks to its fuel mapping for the fuel delivery figure corresponding to the n and alpha of the moment.

So, let us assume that we're making use of engine braking downhill without the application of throttle. This means that the alpha component is ZERO. Hence, there should be no fuel being delivered for combustion. If this is true, why coast with the clutch disengaged?

Your turn!

7. Unless road/load conditions prevent so, do NOT use engine braking. Say you are approaching a toll gate at about 90. You can judge when to decelerate, slow down, brake etc. Judge your speed in such a way that you can pull in the clutch, let the engine go to idle for some time, let the bike coast down under its own inertia then shift down to tackle the speed breakers before the gate. Engine braking definitely uses up more fuel than an idle coasting.
Ride safe.

Would set you back by ~10k including shipping. Performance boost may be by 2 ponies extra. If you think its worth, you may go for it.
A friend of mine got CBR250R 11-12: Yoshimura R-77J CF tip-SS Slip-on - 25,999.00.. for 25k rupees, but has reverted back to stock as he says he gets tired on long trips due to the noisy muffler!

EDIT - 10k OTOH can fetch you lovely gear bro.

1st, I'm loving this. Second - its a long post!

Prior to putting down the text, I'd summarize by saying that I feel that ZERO throttle should send signals to the ECU to avoid regular spray of fuel, hence increasing mileage.

Here's why I think so.

[ATTACH=CONFIG]109727[/ATTACH][ATTACH=CONFIG]109728[/ATTACH][ATTACH=CONFIG]109729[/ATTACH]

PGM-FI system has a two-split configuration consisting of the throttle body and the ECU module.


Layout of sensors
The throttle body module has 3 sensors in the device body.
1. Intake air temperature (Ta) sensor: To allow measurement of intake air temperature, the sensing tip of the sensor is exposed in the intake air passage before the throttle valve. For down-sizing, the sensor terminals are directly mounted on the ECU board.


ECU module component
2. Throttle position sensor (TPS): Located on the end of the throttle shaft, directly detects the throttle opening. The throttle shaft and the sensor rotor are connected via a spring to eliminate a hysteresis in the operation. The TPS is directly fit into the device body and sealed from outside by potting.
3. Manifold vacuum (Pb) sensor: The sensor terminals are directly mounted on the ECU board, and connected to the connecting passage provided after the throttle valve in the throttle body.


ECU boardIdle air control deviceFI system control
The PGM-FI system for small motorcycles controls the fuel injection volume, injection timing and the ignition timing based on signals from the throttle position sensor (TPS) in the ECU module, the manifold vacuum (Pb) sensor, and the crank position sensor that detects the rotation angle. The fuel injection volume, the injection timing and the ignition timing are further compensated by the engine temperature, intake air temperature and the atmospheric pressure to ensure optimum controls under various environmental conditions.


Fuel injection control
For the control of fuel injection volume, two kinds of maps are stored in the ECU and an appropriate map is selected and used depending on the throttle opening and the engine revolutions.
1. When the loads are low, the delicate changes in throttle opening are detected by the manifold vacuum, and the manifold vacuum map determined by the manifold vacuum and the engine revolutions is used.
2. When the loads are high, the throttle map determined by the throttle opening and the engine revolutions is used.


Ignition timing control
For ignition timing, the map control determined by the throttle opening and the engine revolutions is executed to control the ignition timing at the optimum timing.


O2 feedback control
To efficiently use the 3-way catalyst in the exhaust muffler, the feedback system using an O2 sensor is applied to control the mixture near the stoichiometric ratio.


Control of idle air control device
The idle air control valve regulates the intake air volume depending on the operating conditions such as the starting, warming up and idling. When starting, the intake air is supplemented by opening the idle air control valve depending on the engine temperature for easy starting. The opening of the air control valve is regulated depending on the increase of the engine temperatures to control the intake air volume at the optimum level. After the engine reaches the prescribed temperature, the intake air volume is controlled to maintain idling at a constant speed by the revolution-feedback control. This feedback control eliminates the conventionally required idle speed adjustment, thus eliminating the need of maintenance to compensate for the secular distortion.

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