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 XT125r battery keeps going flat .

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   - buy on Ebay UK or Amazon UK

 YEC-8 Battery Charger  -   buy on Ebay UK or Amazon UK


buy new yamaha XT125r stator direct from china see here 

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 ybr 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 


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 .

Yamaha XT125X XT125R 125 blog valve clearance adjustment tappets


Just done a tappets adjustment on an XT125r engine i have removed , ill be fitting the engine soon so ill take some photos of this as i go along .

this ids a very easy job with engine out or in .

make sure you change the o-rings you might get away with it but more often than not no and oil will leak
especially around the cam sprocket cover and drip onto exhaust causing excess smoke .

Yamaha xt125r blog valve clearance tappet
                                                   remove inspection covers ( 24mm)
Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

change all O-rings 

Yamaha xt125r blog valve clearance
                                              remove plastic inspection covers
                                    use a good fitting tool to avoid damage to
                                                                   them .
Yamaha xt125r blog valve clearance
                                                remove camshaft sprocket cover
Yamaha xt125r blog valve clearance
                                                          change this O-ring otherwise this leaks
                                                          directly onto exhaust
Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance
                               turn engine over anti clockwise with crank nut ( 17mm)
Yamaha xt125r blog valve clearance
                      make sure piston is at top dead centre and marks are aligned on the             sprocket ( white marks ) i have painted them white but manufacturer markings
                                                                  are easy to see
Yamaha xt125r blog valve clearance 

make sure lower marks are aligned buy viewing in inspection window

Yamaha xt125r blog valve clearance

then make sure you have free play in both rocker arm 
to ensure you are a TDC on compression stroke (valves closed )

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance
                                                      check clearance gap is with above specs
Yamaha xt125r blog valve clearance
                                                               adjust where necessary
Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

Yamaha xt125r blog valve clearance

easy now just check every thing is tightened to specs and turn engine over a couple of times 
make sure things go smooth and fit inspection covers changing o-rings .


Yamaha XT125X XT125R Front and Rear Brakes Common Problems

 Yamaha XT125r Below are some of the most common brake and braking issues 

Yamaha YBR 125 Front and Rear Brakes Common Problems

brakes are spongy or do not hold 

- air in brake line or fluid leak
-pads/discs worn
-contaminated pads ie oil/grease
-deteriorated brake fluid
-master cylinder faulty/worn
-disc warped

brake does not hold 

-brakes incorrectly adjusted
-brake shoes worn
-leak loss of fluid in braking system


-disc warped
-wheel axle bent 
-brake caliper bolts loose
-wheel warped/damaged
-wheel bearing wear or damaged
-brake drum out of shape

Brake drag

-master cylinder piston seized
-levers or pedals stuck seized stiff
-caliper pistons or assembly seized
-brake pads not installed correct or damaged or foreign object present
-fluid contamination 
-brake shoe springs 
-brake shoe mechanism seized 

Yamaha XT125X XT125R Routine maintenance and service schedule


Yamaha XT125R is a well built machine the engine is excellent too , but all vehicles need regular maintenance , the more you but in the more you will get back out of your Yamaha XT125R .

here is some service and maintenance jobs that are needed on your Yamaha XT125r

Every 600 miles 

-check adjust and clean lubricate your chain
-check oil unscrew dipstick but test without screwing back in 

Every 3700 miles 

-replace engine oil 
-Check / replace spark plug
-clean / replace air filter 
-check crankcase breather system 
-check / adjust valve clearances
-check / adjust idle 
-check fuel system for leakage
-check / adjust cables
-check / replace brake shoes 
-check braking systems for correct operation
-check stand spring and switches
-check forks and shocks for leakage perished seals 
-check wheel bearings , wheels and tyres
-lubricate all levers etc .
-contact clean all electrical connectors
-check tightness of all nuts and bolts 
-check / adjust steering head bearing
-check battery and charging circuit 

Every 6000 miles 

re grease swing arm bushes

Every 7500 miles 

-Replace spark plug 
-new air filter element 

Every 14000 miles

-re-grease steering head bearing 

Every 2 years

-Change the brake fluid 
-replace master cylinder and caliper internal seals 

Every 4 years 

replace brake hose 
change fork oil and seals 

i will eventually have a post on all these i hope so keep reading .