So I've been working on the 350 twin for my dad for a long time now and have been having trouble getting it to run correctly. There were jetting, timing, exhaust, coil, etc issues along the way but I've had it running for testing (about 10 miles worth of test rides and at least 5 hours of running in front of a fan) off and on for the last 3 months. I finally get a set of good coils from a kind soul on the twins forum and start her up and can't figure out why she's only running on one cylinder (very smoothly I might add). I test and sure enough, I've got great spark but the plug is wet. Getting spark, getting fuel, I've checked the timing and valves at least a dozen times, what else could it be.
It was at this point that I felt a total loss of gumption (if you've read Zin and the Art of Motorcycle Maintenance that will make more sense). Not paying attention I knock a screwdriver off my parts cleaner and bend down to pick it up. On the way up I happen to look toward the bike and notice oil on the fins. This bike got a complete re-build so there is absolutely no reason to see oil on the fins. I scratch my head and just stare at the oil for about 20 seconds before it hits me...
I had made sure to torque everything exactly to spec when I assembled it but had not yet gone back through to re-torque the head/jugs. Luckily the 350 is much easier to do this on than many other bikes so I grab the torque wrench and socket and find that the nuts are VERY loose. The many heat cycles did what I knew they would do, just I had forgotten to follow up. Tightened it back down and she's firing on both cylinders again.
Of course this means I'll be going back through the cam chain, valves, timing, etc to get her buttoned up but there was a HUGE sigh of relief when I figured it out. Only wish I had thought to check the basics earlier...
