Yamaha YBR 125 workshop manual
Yamaha YBR 125 parts in the USA
if you have not got one get one Yamaha YBR 125 haynes workshop manual
Yamaha YBR 125 compression testing
compression testing is important , it give an indication of wear in the cylinder barrel and valves etc .
Yamaha YBR 125 cylinder compression values
Standard - 170 psi
min - 148 psi ( investigate cause )
max - 190 psi]
low compression on a yamaha ybr 125 can be caused by many factors
loose spark plug , cylinder head bolt tourque setting incorrect , head gasket damage , valve clearances , cylinder/piston/piston rings wear or damage , cylinder head warp , valve spring broken , walve not seating .
buy a quality motorcycle compression tester
so it will last a long time and check regular
heres some on ebay similar to mine
there are better though
remove spark plug
firmly press the tester into spark plug hole
then open throttle and turn engine over
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