Motorcycle Repair: oil pressure light coming on, low oil pressure, froks

Question
I need some help, I have a 83 Interstate with 42000 miles on it. I got this Bike from My Dad last year. It needed some carb work as it had been sitting idle for about 3 year's. I got that taken care of. The bike ran great.I've put about 1500 miles on the bike since then. A problem started when I took a trip to Kansas City in last September. Until this trip I had never taken the bike on a trip longer than a hour, so this was a test trip so to speak. Everything was fine with the exception of Water temp rising at times. On the return trip, at my first fuel stop, I notice that when i exited the Highway and came to a slow , the low oil pressure light would flicker. Give it a little rpm and the light would go out. Let it Idle and the light would flicker again.I gas up and let the bike cool down for about 30 min and re-started.Everthing fine until stop for gas again. same thing happen again. I made it home from the trip and parked the bike for the winter.I though maybe that my oil was thinning because thr bike was running hot. I've since did a bunch of brake work and re-sealed the froks. changed to 20-50w oil and have been riding around town.no problems. I got onto the Highway this past weekend to go to a bike show about 40 min away and the oil light started to flicker again when I got off the highway. A little gas and the light would go off. I made it to the Bike show ok and parked the bike for a couple hours. Bike started fine no oil light problem until I got off the highway again. So in a nut shell do I have A bad oil sending unit or could there be some thing else that I need to look into. I forgot to mention that the engine does not make any unusal noise when this is happening. The Bike runs great on the highway. I do need to check my vavle clearance as the valves seem to make noise under hard accel with rpm up. I don't this would cause my oil pressure problem put I thought I would mention it

Answer
Bob, you have got the answer. from experience the sending unit is getting weak and is giving a lower pressure reading especially when warm. this is normal for those units and age. just to be sure you should have it taken in and get a oil pressure reading and tell them you want it taken as soon as you pull in to give the best answer or do it yourslef a good auto store has the metric line tap for it. rule of thumb is 10 pounds for every 1000 rpm. but most hondas carry much more than that. as far as the 20w/50 that motor was not designed for heavy oil. the journals on the crank and cam shafts only carry a few thousands of an inch clearance and you can starve one with heavy oil.. 10w/40 is all you need.