Cafe racer problem

[stejack]

Hey

I know that i have only just joined and its a bit pony to be asking for help but.......

One of my current projects is a 2009ish Yamaha YBR 125

This is the fuel injected model which is where the problems start!

The bike will start and tick over for a short period of time then cut out.

During idle if you demand any response from the throttle it just dies!

the first bit of advice i got was that it needs a lambda sensor,

the bike is built from bit (as are most of my projects) so i didnt have the original exhaust.

when I tried to located a replacement I couldnt find one that could take a sensor!!!

Upon closer inspection there isnt any wiring for a sensor on this machine.

Im banging my head against the wall with this one. Can anyone help?

Steve

[iangaryprice]

The Lambda sensor is an essential sensor for the injection system.

It measures the level of Oxygen in the exhaust, if Oxygen is present, then the mixture is weak, if no oxygen then the misture is rich.

The output of the sensor 0.1V - Oxygen present - lean mixture 0.9v - no oxygen - rich mixture.

From the symptoms you describe, the bike runs for the first few minutes - while cold the Lambda sensor is not used, the contrl unit uses preset value to fuel the engine. Once warm it will look for signals form the sensor to workout the mixture setting. In your case it seems that because the control unit is not seeing a signal, it has set the mixture either too weak or too rich for the engine to run.

If you have no wiring of rth elambda sensor, has the bike got the correct wiring harness, or has the lambda sensor wires been cut off.

Also the fuel injection models use a different set of clocks to the carb models. Injection clocks have a fuel injection warnnng light & the rev counter works form different signals.

[stejack]

bugger!

I have changed the clocks! but the harness IS the correct one for the engine.

When I have searched for a sensor online there isnt one listed for this machine?

[stejack]

could this model have an immobiliser?

[Mississippi Bullfrog]

bugger!

I have changed the clocks! but the harness IS the correct one for the engine.

When I have searched for a sensor online there isnt one listed for this machine?

 

Odd, I did a quick search and found the O2 sensors for the YBR125 available from a number of places.

[rennie]

My Mrs had a YBR, my Son had a YBR, both carb. models admittedly

Every YBR I've had anything to do with has been the same though!

They take ages to warm up!

The Mrs's would have to be left idling for at least 5 minutes before it would rev or move

[stejack]

bugger!

I have changed the clocks! but the harness IS the correct one for the engine.

When I have searched for a sensor online there isnt one listed for this machine?

 

Odd, I did a quick search and found the O2 sensors for the YBR125 available from a number of places.

 

please do tell?

this machine is a 58 plate

[Mississippi Bullfrog]

For example https://www.magnumtuning.com/en/detail/motorcycle-bosch-o2-oxygen-sensor-universal-wiring/yamaha/ybr125-custom

They do a chip to replace the O2 sensor as well - not uncommon to do as it generally increases the fuelling.

[stejack]

thanks for that. now as i stated earlier, the is no wiring visable for this sensor nor is there a hole to fit the sensor to the zorst

[Mississippi Bullfrog]

I assume that's due to the modifications done to turn it into a cafe racer. If the original loom had the wiring then it ought to be possible to retrofit the necessary input to the ECU. With the chip option you wouldn't need a hole in the exhaust.

[stejack]

Thanks for the input Bullfrog,however i have just had it confirmed by yamaha that my engine doesnt need a lambda sensor.

They also said a new zorst would be 359.99 plus vodka and tonic!!!!!!!!!!

[Phill]

My 12 plate ybr didn't have a lambda sensor! The bike was stock.

The TPS on the throttle body has an air mass sensor and the fast idle circuit incorporated.

If there is an electrical problem the engine light will tell you by a flashing pattern an error code.

[stejack]

i have an idea that it could be the TPS, that would explain why it cuts out on demand of throttle?

[Phill]

[mention]stejack[/mention]

Taken from the internet:

 

Fault codes are stored on the ECU , these will be shown via the engine fault light on the dash board

as a series of flashes of the light .

The engine management light will come on for 3 secs every time you start the bike , if the light does not come on replace the bulb at rear of clocks .

Codes are all 2 digit numbers , the first number will be read by long flashes of the light , the second

number of the code with be in short flashes of the light .

Fault code 12 - Crankshaft position sensor

Fault code 13 - Intake air pressure sensor

Fault code 14 - Intake air pressure sensor

Fault code 15 - Throttle position sensor

Fault code 16 - TPS

Fault code 19 - No signal from ignition to ecu

Fault code 22 - Intake air temp sensor

Fault code 28 - Engine temp sensor

Fault code 30 - Tip over sensor

Fault code 33 - Igniton coil

Fault code 39 - Fuel injector

Fault code 41 - Tip over sensor

Fault code 44 - Read write error ECU

Fault code 46 - Power supply error to FI system

Fault code 50 - Ecu malfunction

Fault code 51 - Diagnosis cooling fan motor relay

Fault code 52 - relay diagnostics lamp head light

[stejack]

Thanks phill

Unfortunately I don’t have the original clocks