Originally Posted by tbg
Howdy folks. Big fan of the forum.
So I recently bought my first motorcycle, a 1980 R100RT with 110k miles, hoping to get a working project bike I could ride on, and learn some basic mechanics. Unfortunately I got what I wished for.
After a few weeks of riding, I made a 60-mile jaunt, and the positive battery terminal completely melted off. Turns out, the previous owner had installed a new battery, but used a screw without enough thread, stacked on washers. I’m guessing that the screw was a little loose, and the resulting arcing melted everything apart. After getting a new battery, and a fresh, well fitting screw, the bike started with no problems.
Excited that the engine was running, I took the cycle for a spin. About a ¼ mile down the road, as I shifted into 3rd, a knocking noise began, and I immediately lost power. After a trailer ride home, the bike made an awful noise upon hitting the starter, and eventually refused to start altogether. Having read a few articles about the $2k o-ring on the oil filter, my friend and I figured we could diagnose the oil and get an idea of how the bike stood. Unfortunately, our work showed a few issues:
-The starter was fixed by gently touching it. Apparently it was just stuck?
-The oil we drained was pitch black, presumably having been burned.
-The right exhaust and muffler are rusted together, requiring us to pull the entire pipe off. (The Clymer manual recommended pouring boiling water on the exhaust nut if stuck, and it worked!)
-Upon tearing open the old filter, we found small particles of shiny metal, and an inch-long jagged sliver of a light metal-ish composition, which, according to Snowbum’s site, is either off the main bearing from a worn top sprocket and chain (shaft?), or off the cam chain tensioner.
After ordering a few washers and screws from the nearest dealer (unfortunately 4 hours away) we reattached everything, and got the oil light to turn off. Unfortunately, after opening the fuel lines, the bike made an awful cranking/snapping/clattering noise as I applied throttle, attempting to start the engine. In addition, very noticeable smoke began leaking from the left exhaust. Out of desperation, we put in new spark plugs, and noticed the left plug tip was covered in burnt oil.
So, we’re pretty sure that there is something very wrong in the left engine head, where the noise and burnt oil seem to be originating: perhaps a hole in the piston or a blown gasket? This is the first mechanical work I’ve ever attempted, and while I’m having a blast and getting by with my buddies know-how and the Internet, we agreed you guys could probably help us out. I’ll be down next weekend to take the left head off and hopefully take pictures of whatever is inside. I’d appreciate any ideas you all might have!