Sunday, 24 January 2021

Yamaha XT 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 XT125 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 


Thursday, 5 November 2020

Yamaha XT125 R X regulator rectifier testing



Yamaha XT 125 for sale on Ebay UK


Yamaha XT 125 parts for sale on Ebay UK  



First ill show a quick test on diodes inside you regulator rectifier .

You are just checking current flow through the regulators diodes in forward and reverse bias.

Cagiva Mito 125 regulator and charging system testing .










I usually face the regulator this way and test as below 


Connect + side of meter to bottom left hand pin/ connector and negative or common to
upper left hand pin you should get a reading of 0.6 or just under here i get 0.512 so happy with that.



swap the leads around and you should get 0L on the meter meaning current is
flowing one way and not the other and diode inside regulator is fine.


Now do the same but on the far right hand side pins/ connectors 
test both ways again you should get 0.6 or close to it one way and 
OL the other again testing the diode.


Now test between the R/H lower pin and centre you should get a reading one way and not the other my reading is 1.172 and its a good rectifier regulator and show diode working 




Now test between the L/H lower pin and upper centre pin you should get a reading one way and not the other my reading is 1.181 close to above reading  and its a known good rectifier regulator and shows diode working 





Thursday, 22 October 2020

Yamaha XT125X XT125R Oil Pump Test < warning - oil pump failure engine seizure






I am having a lot of XT125s and YBR 125 engines in seized and i am not sure why , maybe bad oil maybe old thin oil .

Maybe running oil to low for pump to circulate , maybe i do not know !! .

or maybe its just coincidence .

here is a test to see if oil is circulating to the top of engine , do it regular and check oil levels 
regular as well , and change oils as per manual .

you need a 10mm spanner , that is it ! .




Yamaha XT125X XT125R flat battery , not charging , overcharging



Yamaha XT 125 for sale on Ebay UK


Yamaha XT 125 parts for sale on Ebay UK  



You need a good battery it a must buy good quality , especially with newer XT125r as they have no back
up kick start , which is a step backwards in my opinion .

find batteries to fit the Yamaha XT125r  here on Ebay UK or here on amazon UK









common problems Yamaha XT125r  flat - weak  battery

- Battery faulty or worn out , replace battery  after checking voltage levels , fluid levels and specific gravity .
- poor terminal contacts ( happens a lot )
-excessive load ( remove some of them lights , stereos whatever )
-faulty ignition switch
-alternator stator coil failure ( test for open or shorted coils )
-faulty wiring ie short on loom or loose connections (check wiring and contact clean all connector blocks )

battery overcharging

- faulty reg rectifier
-defective battery
-wrong battery size

Yamaha XT125r recommended or Genuine battery chargers are listing below




YEC-40 Battery Charger   
Amazon UK

 YEC-8 Battery Charger  

Yamaha XT125X XT125R engine will not turn over












I have had this often on Yamaha XT125r  you press the starter button and nothing happens , the engine does not turn over.



here are some possible causes

-blown fuse
-battery flat
-defective starter motor - or wiring to it
-relay faulty ( built into solenoid )
-starter button faulty ( sometimes need and heavy press to contact )
-starter wiring circuit
-defective ignition switch
-faulty neutral/stand switches  ( had faulty neutral switches on at least 4x xt 125s now )

Yamaha xt125r engine will not turn over

Yamaha xt125r engine will not turn over



My Yamaha XT125X XT125R will not start

 


Yamaha XT125r will not start .





My Yamaha XT125r will not start 


Spark/Compression/Fuel/Air/Timing


You need all the above to get the engine to run.

Remove the plug, reconnect it to the HT lead, hold it on the cylinder whilst turning the engine over and you should see a spark.

Whilst plug is out do a compression test.
Check fuel is fresh in tanks  (put some fuel in spark plug hole)

Check air filter is clean

spark problem - duff spark plug, cap, ht lead, coil - CDI , check timing .

Try the obvious first if you have done any work to the bike check through for possible mistakes .

checks to make , possible causes

engine does not start or is difficult to start
no fuel
-tank empty ( happens a lot )
-fuel tap - vacuum damaged defective
-fuel line blockage
-fuel pump failure

engine flooded
- incorrect carb set up
-faulty carb - carb float

no spark
-ignition fault
-flat battery
-defective spark plug-lead-coil
-defective ecu
-crank position sensor failure/fault
see our posts

stall after starting
- ignition malfunction
-carb or fuel injection system malfunction
-fresh fuel ( you will surprised at how often clean fresh fuel cures problems )
-intake air leaks
-idle incorrectly set - faulty idle solenoid
-short on ignition switch ( worn wires , moisture.)
-wire loom fault - short , check wiring contact clean all connections

compression low
- loose spark plug tighten and check threads
-cylinder head loose - gasket failure - warped
-check valve clearance
-worn piston/rings/cylinder
-damaged valves/springs or not seating properly


rough idle
-ignition problem
-idle incorrect or faulty solenoid
-carb or injection fault incorrect set up
-dirty fuel , always troubleshoot with clean fresh plentiful fuel
-air leaks to intake
-dirty clogged air filter
-air induction fault
-fuel injection fault

recent non starter issues i have faced ,

faulty spark plug , faulty fuel pump , faulty injector , faulty fuel pump hose , ecu failure .

if your engine does not turn over check neutral light it on ill do a complete post on this soon

that is about all recently if i remember any more ill update .