Hi all, just found this site while searching for info on a bike I'm re-commissioning for a friend & hoping someone may be able to help with a few things...

Firstly, the engine (YPVS-LC, 5X5 prefix) is waaaay down on power since I got it running. Compression & leakdown are fine as the motor has low hours since a top end anyway, first problem I ran into was a loose red wire from the stator putting the timing out which I fixed, then checked the powervalve nut which was loose. I re-tightened this, checking the PV was right way up & was hoping this would sort things but no joy.

I'm thinking it's running rich as it starts with no choke but I haven't run it long enough to read the plug, even so a rich mixture wouldn't make it this lame surely? I reckon it's making no more than 2hp, even my old 45,000mile 100 scooter is more gutsy! Is there anything I'm missing here that would kill all power/torque yet still allow it to start first kick?

Sorry if that's a bit of a long confusing post btw, I'm just excited to be working on a 2t again!!!

Any help mucho appreciato, Dan.

Oh, hope this is of use to you all - it's yamaha parts PDF's for loadsa models...

http://www.ytcn.nl/archief/index.php?dir=Yamaha+Parts+Manuals+ALL+1950-1996/YZ/

Cripes, does anyone besides me actually come on here? I thought my Suzuki DR400S was an unpopular model but it seems that it still has more of a following than all classic yams put together!!!

Sorry Dan-San, that nobody answered yet. Most readers are street oriented and a 5X5 (1982) MX bike is a rather different category to most guys. But I will try to find out something for you.
Kind regards,
Ludy Beumer

Ah, there is someone else on here then. I was beginning to wonder...

To be honest I've all but figured the beast now, some doofus put the piston in backwards when it was last rebored! This has snapped a ring but fortunately not done any damage to the actual bore. Also there was a gearbox problem which I've put down to a bodged selector shaft which allows the pedal to hit the sprocket before selecting a gear...

Not to mention the grooves in the water pump shaft which result in the 'box filling with a nice creamy mixture of water & oil.

Hopefully I've found a source of the parts needed, we shall see.