This mini trail has been sitting in my barn for nearly 6 years. So I finally gave it some attention. Did a complete disassemble for clean and paint. I had originally planned to try a true restoration on this one, but I just don’t have it in me. Especially the cost of doing it true. So I’m going to do another one of my low budget refurbishing. I’ve got a long way to go, but it’s fun getting there.

imgur.com/a/qYHEm8s

That brings back memories… a blue one from the late 60’s..

Sold my Z50 a few months ago and picked up an HD X90 Shortster. Planning on putting a clone motor in it.

I had to google an X90. Be good to see progress when you find a motor.

Inch by inch. Slow progress, but it’s progress. I had to source a new cylinder head casting. This one had cracks galore all around the exhaust outlet which I have learned is a common problem. Lots of aftermarket heads from China but I was warned to stay away from them. So I finally found one on eBay that looked like it was a good casting so I made an offer of $80 and it was accepted! Now I need to source a good machine shop that can do the valve job on it. The exhaust pipe was seized into the head but it didn’t matter much because it was rotted thru. I will buy one of the many cool stainless pipes available.

imgur.com/a/WiepgaE

Getting closer. I need to order new tires and an aftermarket exhaust. Plus I need to repair the cylinder head which has some cracks on the flange where the exhaust mounts. I’ve machined the head and made the piece for the repair. I just need to take it to my fabricator for welding. My paint guy didn’t match the orange color as well as he has on three previous bikes. But it’s not too bad. I painted the top center section of the tank and left the sides original including the tank decals being original. I left the side cover original but had to repaint the forks because they must have been salvaged from a red bike.

imgur.com/a/gmZga85

imgur.com/a/b6AtMdJ

One thing to point out about the exhaust outlet. Even a good head casting is missing a big section on the surrounding wall. The head on the right is a good casting with no cracks. The head on the left is my cracked head.

I bought the other head for $80 only to discover that it was an earlier model with a smaller combustion chamber and smaller valve train. Same original casting though! And that is all I focused on when I bought it. Win some and lose some. So far I win more than I lose!

imgur.com/a/fimTthW

Perhaps a trail 90 would fit?

Perhaps. But I don’t have a trail 90 engine to use. So hopefully my head repair will work and I can stay with the original engine. A friend of mine on the SCR950 forum said his neighbor rebuilds these little 50cc engines and ships them all over country. Even overseas. He said he just built a performance engine with nitrous injection. 

That is a Z50 cylinder head you bought (39mm bore).....looks like you either have a 70cc top end on your Z OR someone stuck a 70cc head on there which would have lowered the compression to zilch
The early 70CC top end looks exactly like the Z50 besides the combustion chamber and intake/exhaust port size.
Looks like a nice project, good luck!
- Ray