Welcome to Project YZ

1980 Yamaha YZ125G Restoration

Introduction Page

Why I created this site.

NEW! Updates listed at the bottom of this page.

This site is a chronicle of my first attempt at restoring a vintage motocross bike. I decided early that it would be fun to document my experiences and create a web site to help others restore their vintage bikes.

How hard could it be to restore a vintage motocross bike?

Well during my vintage restoration there were many false starts, changes of direction and confusion involved. After searching the internet I found no web sites that detailed a complete start to finish restoration of a vintage motocross bike.

My site contains a great deal of information. Take some time to read through the entire site. I believe there are some tips included here that you will not find anywhere else.

Even though this site is about restoring a Yamaha YZ125G many of these ideas will apply to other vintage motocross bikes. My hope is that this site will be helpful with your restoration.

You may discover that it would be better to contract a professional to restore your bike. At the very least I hope you get a laugh or two out of reading my saga.

Please feel free to write with any comments or questions.

Thank you.

Photo by www.vintage54.com

May 5, 2007 - I raced my very first vintage event on the YZ. I didn't get to do any testing and had been putting off going to the races for so long that I just went. I raced at Evansville Raceway in Berwick, PA. Lot's of nice comments on my bike one of the most common being "You really gonna ride that today? It looks too nice to race."

Yes I rode the bike and I had a great time. Unfortunately I had some issues with the bike pinging terribly. I thought it was the jetting of the carburetor so I richened the jetting right after practice. I went from a 340 main jet to a 360 main jet and richened the needle one step. I raced the first moto and the pinging was just as bad if not worse, so I babied the bike so it wouldn't seize.

Between motos I searched for richer Mikuni main jets and I found a 400 main jet that I promptly put in along with a 85 pilot jet and richened the needle as far as it would go. Still the bike was pinging even though the exhaust was very smoky.

I E-mailed a bunch of friends and recieved many different ideas on what could be causing the pinging. When the top end came off of the bike I found what happened. The head gasket leaked very badly. Again everyone had differing opinions on how to fix the problem. I choose to have the head milled by Elmsford Speed Shop which cost $45.00 to get done. I have not yet bolted the bike together which means that I haven't tested it yet. I will update the site when I finally get it together and straighten out the tuning issues.

I also discovered a few things that I thought would work great but turned out to be not so good. The worst was painting the cylinder, head and exhaust pipe with clear high temperature paint. Maybe it was just the paint I used but it stained a nasty brown color from the dirt and the heat. I used laquer thinner to remove most of the dis-colored paint from the head and it did not all come off. I will need to sandblast both the head and cylinder again when I tear down the bike at the end of the season.

I will update the site when I have more information. In the meantime you can check out how dirty I got the bike by going to the Photobucket site listed a little further down this page.

April 24, 2007 - Added Ben's YZ125G to the comments page.

December 28, 2006 - Updated Comments page to add before and after photos of your YZ125G projects. Send a clear before and after photo with a few short sentences about your bike or experiences and I will post it on this page.

December 26, 2006 - Newly updated photos of the completed bike.

Project YZ Photo Bucket Album

August 25, 2006 - Reproduction intake manifolds found!

Rob Wagner of Queensland Australia now makes the very hard to find intake manifolds.

Contact Rob via e-mail at ozktmparts@bigpond.com his web site is located here www.4RoBs.com.au His complete contact info is located on the Links page.