So I've been thinking about doing the top end on my 1983 Nighthawk 650 for a few reasons. The compression on all four cylinders is a little low at 120 psi. That is tested with the engine warm and throttle wide open. The shop manual spec is 170 psi. But, correcting for my elevation of 7,000 feet, that would be more like about 134 psi. So maybe 120 psi isn't too bad???
Also, I'm getting oil in the drain tube that comes off the separator tank attached to the the crankcase breather - maybe an inch of oil will collect over the course of a 50 mile ride (pictured). The airbox which is connected to the separator tank also has oil in it. My guess is that I am getting some blow by past the rings which is forcing vapors out the crankcase breather into the separator tank and airbox where they collect. The bike doesn't visibly smoke, but I can smell either oil or unburned gas when I let the bike idle in the garage. The plugs don't look too bad - a little too brown maybe, but dry (pictured). Originally, the number 2 cylinder was only reading about 105 psi. But now that all four cylinders are at 120 psi, I am having second thoughts about doing a top end. The top-end job would include a cylinder hone, new rings, lapping valves, new valve seals, new gaskets, and anything else I might run in to. I think I could do it myself. I already have a top end gasket kit. Rings would be about $100. As long as I don't run into other issues, the cost isn't too bad. What do y'all think? Is it necessary? -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/nighthawk_lovers/d584d518-3f7d-40db-951d-131bc7880e0c%40googlegroups.com.
