I purchased this bike Spring 2012 from a retiree in Duluth who tinkers and restores vintage bikes for fun in his free-time. It seemed to be in great working order when I went and looked at it. It took a few visits, 3 test drives and about a week of deliberation to make a deal, but I took the plunge and bought was I thought was my first reliable bike (I also have a 1972 Ironhead Sportster that had been my dad's since '76).
A few minor maintenance items were necessary along the way: cleaned carburetors and replaced a leaky float, new gel-style battery, replaced chain and sprockets (and lost part of my finger being an idiot). After a few summers of fun and minimal trouble, it started to act tired.
After two cold, ill-prepared rainy days riding through Wisconsin to Minneapolis, I lost oil pressure almost half-way home to Duluth on the third day, riding two-up from Minneapolis. It was struggling under load and I could see a little oil on the right side of the engine case. I stopped at a station for inspection, and found I was a half-quart low. I topped it off and decided to continue. The bike managed okay the rest of the way with a few stops. In the 100 miles home it went through a quart of oil and when I got home I parked it for the season. Upon further investigation I found one of the spark plug wires was melted at the cap and wet with oil. Compression on a few cylinders was also low (but not gone)
Last February I finally decided I had time to deal with it, and I took it out for one last ride before tearing it down. It was a freakish 40 degrees out one day and I decided to take it to the local DIY carwash for a bath before dismantling. It ran beautifully, purring past the snow piles by the side of the road. I got it home, pushed it up the stairs and into the living room, and proceeded to tear it down for in-depth investigation.
The oil leak appeared to be coming from the top of the cylinder, and I assumed it to be a bad o-ring. I hadn't taken an engine apart since high-school shop class, and I think I got a little excited and went further than necessary. The bike has 38,xxx miles and I decided to check the rings and for some reason decided I might as well just check everything and do a complete top-end rebuild. I probably could have had the bike back on the road and reasonably happy with far less work but, here I am.
The engine came out and I took the heads and jugs off in the living room and split the cases on a work bench in my bedroom last winter. In March I bought another bike (2009 Yamaha WR250) and have had too much fun riding to get much further work done since then. I moved from Duluth to Minneapolis about a month ago, and the engine is finally out of boxes and back on a bench in my bedroom until I'm ready to reassemble in our shop down the street.
At this point, I'd like to measure the cylinders to see whether new rings and fresh honing will suffice, or whether I'll need to rebore. I'd also like to determine whether any bearings or other internals need replacing. After this is done I would like to clean and refinish the cases, make sure they are straight and need no machining or resurfacing before reassembly.
Any input or help along the way would be greatly appreciated, as I've never gotten this deep in a multi-cylinder engine and want to do things right. I haven't used plastigauge or micrometers since high-school shop class and I was probably stoned when I did so I'll be re-learning some of this stuff and entering new territory in a lot of ways.
Glad to have found this community, I'll update as I make progress!
