poolroom15 wrote on 03/29/20 at 19:17:03: Does the petcock go bad internaly and leak into the intake thru the vac hose or external so I know what to look out for?
The diaphragm goes bad in a couple of ways.....and your results may vary. We believe the diaphragm is not resistant to ethanol, and depending on the fuel in your area the petcock can work for years, or it can fail relatively early.
One potential failure is the diaphragm becomes stiff, and it fails to flow fuel. This can cause weird symptoms and often has folks looking for electrical problems, carb jetting or fuel tank venting problems. The problems are often intermittent and the bike can run fine around town - but stop running at highway speeds. The stiff diaphragm often works at low throttle settings and low speeds where the intake vacuum is high - but stops working when higher throttle settings are required and the intake vacuum drops.
The other failure is when the diaphragm starts leaking. It runs fuel down the vacuum line and into the intake port. The fuel then leaks past the intake valves and past the rings and it dilutes the crankcase oil and can even fill the crankcase with fuel.....and it can also fill the air box with fuel. The symptoms of this are often a very sluggish engine as the crank tries to rotate submerged in a liquid fuel/oil mix.
A few members like Stewmills like the convenience of the stock petcock and have gotten away with using it permanently - but he keeps a rebuild kit with him in case he needs it, and it watching for the symptoms to show up. Others of us have been riding since the 60's and we are used to shutting the petcock on/off as it is a habit, and we like the reliability of the manual Yamaha Raptor petcock.
The cam chain tensioner is just something to be aware of - it is only a problem if you ignore it for an extended period. It appears short local rides with frequent heating/cooling cycles tends to cause the cam chain to stretch faster than long rides. I would suggest opening it up around 10,000 miles and take a measurement, and this will give you a reference for how your riding style is affecting the cam chain.