I cannot speak for all engines or kits but here is my story. I have an R/S .035 and GEBE kit on a 26" Schwinn full suspension all aluminum frame bike. No special wheels or spokes or other add-ons other than a good headlight, taillight and better than stock seat. I weigh over 200 lbs. In about 4 months I have put over 1500 miles on it at different speeds and distances. At each tank of gas I do a cursory check for problems. So far, I have done absolutely NOTHING to it but change oil, add gas, tighten/adjust things and ride. Follow the rules for installation, break-in, maintenance and safety. Lemons are made by people. I believe that any of these kits, if operated according to the owner's and maintenance manuals will operate many thousands of miles and many years. As Dockspa and Dean said, YOU need a rest. The engine does not. Stop for YOUR sake and Maintenance only. If the engine is heating up, find out why and fix the problem. Otherwise just ride, be alert and enjoy.