Thursday, 4 November 2021

Honda CBR 125 engine rebuild parts

 These are the parts i use to rebuild my Honda CBR 125 engines with


Firstly you need good gasket sets i always use thes NE brand ones never failed me yet





I use either SKF or Koyo bearings 




                             Buy these on Ebay UK here 



Athena Seals New oil seals need to be fitted on every rebuild                                                                           
Cagiva Mito Engine recommended rebuild parts





Ive had very good success with these piston from firefox but if you can find genuine on an auction then buy them
 first.








For barrels i always try to rebore and oversize piston.

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.


Buy Honda CBR 125 NGK spark plugs here on Ebay UK


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