hi all,

i have just purchased a 1986 rd125lc and am a complete newbie to these bikes. how do i know if my bike is a YPVS model?

Hi"  you will see the cylindrical  shape  near exhaust side on barrel,, with wires .hearing a whirr when key on

It's got ypvs in dirty great letters on a fitting on the right hand side of the engine. 

If you have a learner legal (haha) model it may just have what looks like a bolt sticking out of the rhs of the barrel. 

Either way Google mk1 and mk 3 rd125lc. The mk3 had ypvs, the mk1 didn't. Look at the barrels on the engine. The difference is obvious. 

be prepared for regular top end rebuilds if the power valve is active. i had a TZR125 which was faultless until i fitted the ypvs servo. didnt take long for the piston slap to begin after that. was good fun though.