Sunday, 24 January 2021

Honda CBR 125 How to test spark plug with multimeter to see if is it is good or bad

 Its a very easy but useful test to make sure your spark plug is ok , you may need to clean the electrode to ensure you get a good reading but all you then have to do is set meter to read ohms and measure from the spark plug cap end to the electrode tip , and then from end to body to make sure no leakage to earth.


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How to test spark plug with multimeter to see if is it is good or bad

Get set up turn meter to ohms reading on dial and clean the electrode as below 

How to test spark plug with multimeter to see if is it is good or bad

Test between end of spark plug where HT lead cap fits and the tip of electrode the reading is very low only 1.2 ohms 

How to test spark plug with multimeter to see if is it is good or bad

on a dirty part of electrode the reading goes wild and eventually read 188.9 ohms so very bad and to avoid this clean electrode tip 



How to test spark plug with multimeter to see if is it is good or bad


Next test from spark plug cap end to the body to make sure no earth leakage your meter should read OL which is a good reading as it signals no leakage to earth via the body.

How to test spark plug with multimeter to see if is it is good or bad

See video of this process below 


Wednesday, 16 December 2020

Honda CBR125 R video series of youtube playlist






Just collected all the Honda CBR125R videos into a Youtube playlist 

Honda CBR125 R video series of youtube playlist


Video series of strip down and rebuild of Honda CBR 125 R engine CBR125 CB125R , top end cylinder barrel piston and head removal , timing chain and tensioner , crankcases split , gearbox clutch and crankshaft removal. For more in depth advice go to our blog link above.

Click link below to see the video playlist for Honda CBR125

Honda CBR 125 engine and repair and maintenance - YouTube







Saturday, 19 September 2020

Honda CBR 125 No spark issues troubleshooting

Honda CBR 125 No spark issues troubleshooting



 Honda CBR 125 No spark issues troubleshooting





Going to do a post on not sparking , as just come across this again on a bike and id forgot everything
so had to go through all the tests again .

Id just like to say i am not really that good with electrics but i know something test first , do not buy parts and read and learn as much as you can  .



First off check all easy stuff .

So -

Fuses , Check all of them , make sure they are seated corrected actually pull them out clean contacts and refit spray contact cleaner in the terminals

Battery , make sure its fully charged remove from bike and recharge dont just guess ,
and whilst doing this clean up the battery terminals and the negative and positive wiring terminals .

Test battery at the negative and positive terminals
If you have a voltage meter you can do some basic tests.
When the engine has been off for at least 1-2 hours with ignition key turned off,
100% Charged 12.60 to 12.8v
75% Charged 12.4v
50% Charged 12.1v
25% Charged 11.9v
0% Charged less than 11.8v

Connections and Connector blocks , go though all the connector blocks take them apart spray contact cleaner inside then then put them back together repeat this a few times on each connector as it will clean the contacting surfaces .  If there are any home made repairs or connections redo them , its sound like a lot of work but ive lost count of how many non running bikes i have bought and its been a faulty wiring connector .

Side Stand and Kill switch , fully confirm that these are working properly with a multimeter do not assume they are ok , do not buy any parts until you have tested these , ill do these tests on a post one day but they are simple , see the video below and the recommended book as well .

Generator test , tbh i am sure the bike would run with a faulty generator but probably not for long
so i test this now , its an easy test and at the very least confirms it working or not , see our post on this here .

Pick up coil test similar to a crank shaft position sensor you can test the resistance with a multimeter and check it against the measurement in the CBR 125 workshop manual and you can check the signal by back probing the wire connector and using a oscilloscope see this test here .

HT coil , Next i would test the ht coil , first id test the primary side for 12v whilst turning the bike over , if you have got 12v here then test the coil if you have not got 12v to primary side of coil , then
its likely to be ECU ( if its not wiring fault ) , if you have 12v to here great you just eliminated all the expensive stuff , test the HT coils primary and secondary sides read this post here  .

CDI , if all else has failed try a known good CDI , but prior to fitting make sure all is function
properly on the bike it might of burned the old CDI out for a reason , ill do a CDI test post one day
if i can figure it out  .

Rectifier regulator , You should have found the problem buy now i have never got this far , now
the rectifier only changes the output of generator to DC to recharge battery and run lighting system so this will have nothing to do with the ignition system , but some have told me they changed this and
they got a spark and seeing as all else has failed !!  .

Oh someone pointed out i never mentioned the ignition switch , which is true , ive never come across this myself but it would be worth check continuity on the ignition switch .


Here is an Excellent video on NO spark fault finding watch it all !!









Honda CBR 125 No spark issues troubleshooting



Tuesday, 21 July 2020

Honda CBR 125 fuel injection fault codes engine management diagnostics


  for more advanced trouble shooting 



Honda CBR 125 fuel injection fault codes





Fuel Injection ( EFI ) Fault Diagnosis and Checking​


If the fuel injection system ( FI ) warning light on the instrument cluster illuminates when the motorcycle is running, a fault has occurred in the fuel injection/ignition system. The engine control module ( ECM ) will store the relevant fault code in its memory and this code can be read as follows using the self-diagnostic mode of the ECM. While the engine is running and the motorcycle is being used, the FI light will come on and stay on. When the motorcycle is on its side stand and the is running below 5000 revs the FI light will flash, the pattern of the flashes indicating the code for the fault the ECM has identified.

If the engine can be started, place the motorcycle on its side stand and then start the engine and allow it to idle. Whilst the engine is idling, observe the FI warning light on the instrument cluster.

If the engine cannot be started, or to check for any stored fault codes even though the FI light is not illuminated, remove the seat to gain access to the fuel injection system service check wiring connector, which is a white 3-pin ( 2 wire ) single sided connector inside the rubber boot close to the tail light.
Ensure the ignition is switched OFF then bridge the outer terminals of the service check connector with an auxiliary piece of wire.
With the terminals connected make sure the kill switch is in the run position then turn the ignition ON and observe the FI warning light.
If there are no stored codes the FI light will come on and stay on.
If there are stored fault codes, the FI light will flash.

The fuel injection system warning light uses long ( 1.3 second ) and short ( .5 second ) flashes to give out the fault code. A long flash is used to indicate the first digit of a double digit fault code ( i.e. 10 or above ). If a single digit fault code is being displayed ( i.e. 1 to 9 ) there will be a number of short flashes equivalent to the code being displayed.
For example, two long flashes followed by five short flashes indicate the fault code number twenty five. If there is more than one fault code, there will be a gap before the other codes are revealed ( the codes will be revealed in order , starting with the lowest and ending with the highest ). Once all the code(s) have been revealed, the ECM will continuously run through the code(s) stored in its memory, revealing each one in turn with a short gap between them.

Once the fault has been identified and corrected, it will be necessary to reset the system by removing the fault code from the ECM memory. To do this, ensure the ignition is switched OFF then bridge the terminals of the service check connector as before.
Turn the ignition ON then disconnect the bridge wire from the service check connector.
When the wire is removed the FI light should come on for approximately five seconds, during which time the bridging wire must be reconnected.
The warning light should start to flash when the bridging wire is reconnected, indicating that all the fault codes have been erased. However, if the light flashes twenty times then the memory has not been erased and the procedure should be repeated.
Turn off the ignition then remove the bridging wire.
Check the operation of the warning light ( in some cases it may be necessary to repeat the erasing procedure more than once ) then replace the seat. 




1 Engine runs normally Faulty MAP sensor or wiring

2 Engine runs normally Faulty MAP sensor / vacuum hose

7 Engine difficult to start at low temp. Faulty coolant temp. sensor or wiring

8 Poor throttle response Faulty throttle position sensor or wiring

9 Engine runs normally Faulty intake air temp. sensor or wiring

10 Engine runs poor at high altitude Faulty atmospheric pressure sensor

11engine operates normally Faulty speed sensor or wiring

12 Engine does not start Faulty no. 1 fuel injector

13 Engine does not start Faulty no. 2 fuel injector

14 Engine does not start Faulty no. 3 fuel injector

15 Engine does not start Faulty no. 4 fuel injector

18 Engine does not start Faulty cam pulse gen or wiring

19Engine does not start Faulty ignition pulse gen. or wiring

20 engine operates normally Faulty EPROM in ECM

21 engine operates normally faulty oxygen sensor

23 engine operates normally Faulty oxygen sensor heat element

25 engine operates normally Faulty knock sensor or wiring

Honda CBR 125 fuel injection fault codes