"Somewhat" as I gain experience by working on my machines. The little four has needed little over the 3+ decades I've ridden it. First problem, & the only one ever with the bottom end was an engine lockup at about 30,000 miles. Being an experience mechanic I took it apart, (with the help of the Clymer's manual), & found the primary chain had failed. It was stamped: "Hyvo, made in USA"! The replacement was Japanese and has been in since. By then I was not happy with the anemic performance so tried a few things. Overboring 5mm to 52 total gave 425cc. The cylinder liners are thin, but not thinner than my BSA B50MX with 550cc kit. The mod greatly increased the low end torque but predictably did not help top end performance. I also had oil leaks from the top end oil gallery so pulled the head. The ports were rough & poorly blended compared to my Brit bikes so some careful work with cutters & files cleaned up the contours. The persistant leaks were caused by the rubber cylindrical seals not being confined within the head gasket, allowing them to mushroom out & loosing the sealing pressure. I took a compression sleeve from a brass tubing fitting that was the right size, & cut it in half, across the diameter. After filing & sanding the two pieces, now having triangular cross section, to 0.060 thickness, I placed them over the rubber sleevse. The 0.060 made them slightly higher than the 0.050 head gasket. Now they seal for years without problem. The difference in performance is remarkable & I have shocked a lot of riders of other machines! Not a superbike, but it is a very lively little machine. The next time I pulled the head was at about 100,000 miles when low compression was noticed on one cylinder. The rubber seals had self destructed but the metal rings held the oil without leaking. The compression problem was solved by replacing one exaust valve, also the cam chain guide & tensioner blade. Recently, at 190,000 miles the engine started using a lot of oil. Teardown revealed one piston with shattered top ring which damaged the bore & piston as well as pitting both valves. Dropping in a replacement sleeve & reboring as well as the two valves & one other fixed the problems. Also replaced the cam chain & guides again. While I was at it I dismantled the bike, cleaning up & painting as needed. (Everything needed attention). I now have 199,000 miles & the bike runs much better than new, (and looks good, too). There have been a few other, minor repairs but it has never left me stranded.
For comparison, I have a lot more than "somewhat" experience repairing my Matchless G12CSR that I've owned almost as long!
