If it does add oil they ain't going to last for ever. You could go to a kart shop and buy a head temp gauge and monitor the temp. American power sports sells a nice gauge and it has a tach and a cht tap to boot. it can remember your max rpm, head temp and cht. all this cause when racing you ain't looking to see if your engine is being over revved or if you exceeded at max temp etc you are trying to get around the guy in front or keep the guy behind you behind you not worrying about the abuse the engine is taking.
The price for this little gauge is the price of an engine kit last time I bought one so I don't run one as I said I don't worry about the temp and weather or not its going to melt. I worry about how far am I going to have to pedal this thing if it does break and it will more than likely be a flat tire. So far I've made it home with out walking even when I broke an axle.

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norms-iron-works.tripod.com
motor assisted bicycle engine headlights that work off of your white power wire. check it out