Sunday 10 August 2014

Yamaha YBR 125 will not start .



Yamaha YBR 125 will not start .






My Yamaha YBR 125 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
-igntion fault
-flat battery
-defective spark plug-lead-coil
-defective ecu
-crank position sensor failure/fault
see our posts

Yamaha YBR 125 Not sparking no spark diagnostics

Yamaha YBR 125 electronic ignition system


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 ive 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 .



see more Yamaha YBR 125 blog posts 


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