Project YZ80 Restoration

Yamaha YZ80 Restoration

Vintage Motorcross racing motorcycles are making their way back into the mainstream again. My brother and have teamed up to renew/restore as many of them as possible. This is something fairly new to him, though I have brought a few vintage rides back from the near grave before. I also have a master small engine degree under my belt that has been utilized from time to time. My brother on the other hand has his experience more with removal and reinstallation of car engines and repairing a farm tractor a few times, he's no stranger to tools and knows his way around a wrench. He's also brought an old Honda V65 back from the clutches of the motorcycle reaper.
Here we are going to take this Yamaha YZ80 from it's worn out status, renew and restore it back to it's former glory. This is a 1990 YZ80A that among other small things needs a new top end.
 Creation of this blog is from finding very little information on the web on these bikes, most sights are dedicated to the big brothers of the YZ brotherhood. We enjoy the larger YZ's as well but just thought the little brothers needed a place to be recognized. Join us as we fix, repair, replace, search for elusive parts and make this bike scream again.      





When we picked this YZ80 up it was covered in red dirt and grime, so off to the carwash to clean some of it off.



 A ton of the grime was washed down the drain giving us a better look at what was underneath.

                    
There are more parts in the truck that go on the bike of course

 Being that the cylinder had already been removed by the previous owner we had seen the damage to the top end. Problem was, the piston was not there to inspect but the head was. Someone had done a ring job and evidently, somehow, a washer got in on top of the piston and punched a hole in it. I'm guessing by the cylinder head condition; that and the fact we were told there was no compression what-so-ever. The grandfather had given us some helpful information on that piston, he said it only had the one ring piston in it. To me, that would mean it was the factory sized piston.  His grand kid, it comes to light, took the piston with him as a souvenir.

Couple of things to note here, piston jobs are a common occurrence. Normal wear and tear, dirty air filters, wrong oil gas mixture can all lead to a piston failure. It's going to happen at some point. The cylinder, luckily, has no score marks nor damage at all, we might be able to hone it, perhaps go one size up, we'll see after taking some measurements. Look close at the engine clutch cover, it has a groove worn in it from the shifter which has been bent in slightly. No big deal there really, just time to repair both.   

As stated before, the wash did away with a lot of the grime. A yellow plastic cylinder cover is used here to keep most the water  out of the engines bottom end while being subjected to high pressure to remove that nastiness.