In the beginning I thought this would be a simple project, but as it turned out it wasn’t. The prior owned had some one work on it that had now idea how an engine works. As it turned out the machine had sat so long the inside of the cylinder had rusted to the point were the piston was locked in place. Out the motor comes. After disassembling the motor I discovered that I could rotate the crank so the cylinder would rise enough so that I could get some wood blocks between the crankcase and the bottom of the cylinder. I have a mallet with a long plastic handle on it. I put the handle down the cylinder so the soft plastic was against the piston and gave it a tap. Nothing moved, so I applied my propane torch to the cylinder, constantly moving the torch so I don’t melt the aluminum. After ten minutes of heat I gave the motor another blow and I could see the piston move a very little bit. I then sprayed a lot of penetrating oil down the cylinder and hit it again until the piston was free enough to allow me to pull the cylinder all the way off the engine.
The cylinder needed boring out. Getting oversized piton and rings was a quest for such an old machine. As it turns out the XL125 wasn’t as popular of a machine and many sizes of pistons and ring as well as many other parts are now discontinued. I ended up going with the 0.50 piston and 0.75 over rings. You can always grind the ends of rings to the proper fit. It’s fussy work to do, but it can be done. The cylinder head was pretty ugly too. I found a valve spring compressor that seemed small enough to fit, but I still ended up having to grind down the legs to make it small enough to fit the Honda head. After pulling the valves out I knew I was in trouble. I had always sent out valve jobs, but no one was telling me anything in the way of a reasonable price. I started looking around and valve cutting equipment wasn’t cheap. A single cutting head was a lot more that I thought, and a whole set was more than I paid for the bike. Sure I wanted to get something that I could use more than just once, but Christmas was on the was so I had to be budget minded. I started looking on eBay for any deal I could find. I found an original Air powered official valve seat grinder that few were bidding on. I was persistent enough and one the auction. Now Just before Christmas and I have no time to work on it. When the valve grinder came in I was able to grind the valve seats and hone in the valves on one Saturday morning. By the afternoon I had the engine assembled and ready to mount. It wasn’t until after the new year that I was able to load the motor in the frame and then put all the parts back together. Snow snow and more snow kept me busy. Shovel plow, shovel plow, it seemed my life was taken over buy the forces of nature.
Finally a Saturday morning where I didn’t have snow to push and it was warm enough to consider riding it around the back yard. I still couldn’t get the motor to start. Some one had put grease in the motor instead of oil. Between the assembly lube and the grease in the motor the rings just couldn’t seal off well enough to make compression. I discovered that the spark advance unit had also been taken apart and put together 180 out of phase. After correcting that I put AFT in the motor to wash out the grease. I know that I should have done all that before, but this was supposed to be a weekend project. I didn’t think that I’d find so many mistakes on one machine. I used the kick started to turn that motor over for about an hour. I decided that I’d pull the drain plug and let it sit overnight. The next morning I was ready have at it. A few house hold chores done and out to the shed. I thought it would be a good idea to clean the work bench first. My coat must have grabbed the bike just enough to start it tipping. All of a sudden the bike hit the back of my legs throwing me against the work bench tearing a hole just below the knee on the back leg of my pants and slamming me to the floor ripping my pants down to my knees. I threw the bike off of me and pulled my pants back on. The pain was more than I could handle so I went inside to see what damage had been done. Here I hadn’t even ridden it and I have my fist injury. There was a tear through the pants so after removing them I found I had a gouge that ran from just below the knee eight inches long. Since I generally don’t bruise right away, a box of band aids and a cup of coffee to calm down did the trick.
I headed out the shop again feeling my knee creaking, the muscles in the leg now so tense that I can feel the blood coming to a slow and I couldn’t move my angle very well.
I made it to the shop and then fill the crankcase with more ATF. I figured it was time to turn the key on The compression felt good this time. After a few kicks I the motor popped through the exhaust. I tightened down the head pipe and pushed the machine outside. A few kick more and the motor started. It didn’t stay running very long. I pulled the carb to find that from sitting in the shop there was now some ice in the jets. I blew them clean and placed the carb back. One of two kicks later and the motor was running. As soon as the motor started to heat up smoke poured out the exhaust pipe. Now it would seem that that was backwards. But after thinking about it for a while If some one load the engine full of grease then I was thinking that the same applied to the exhaust pipe. A few laps around the back yard a little above idle and the motor still sounded good. The pipe must have started to clean out because the smoke was hardly there anymore. The spark plug was black from burning off all that grease. I drained the AFT out and the result was very black and goopy sludge. I put new 10-30 oil in and then rode it for a few hours later that day. The next Saturday I let the first learner ride it around the back yard. Between the slippery snow and the new ride never riding before it was fun to watch. Come this spring I can let it be ridden more, and then get the turn missing signals for the rear and make it road worthy. For now it sits in the motor shed waiting to be ridden again. ]]>