missing oil pressure after oil change

[arve]

Hello.I have recently aquired an '81 gs 550 m KATANA,in fairly good original condition with just above 20.000 miles on the clock.:-DIt was working all fine,until it came in contact with the new oil i bought,CASTROL GPS 10w-40 motorcycle specific oil.At the store,before riding home I added alittle of the new oil since I thought the level was a bit low.On the last straight piece of road before home I gave alittle extra throttle and when I released it not to hit the car ahead the oil lamp came on.I grabbed for the clutch to stop the engine before it was damaged,but it didn't work!:shock:There was no resistance at the lever,and I had to stop in gear.Got it in neutral, started again and the lamp came off fairly soon but the clutch was still inoperable.Also,some clattering noise came from the engine.After some idling and revving in neutral the clutch came back,and the noise disappeared.I drove carefully home,thinking the problem was caused by sludge in the oil system,since i knew the bike hadn't been used for several years before i got it.Changed oil and fitted a new vesrah filter(there was plenty of black goo inside the housing when I took the old one out),thought it'll do the trick but no.At the first hard acceleration the same damn thing occured.Then I thought I'd manage to wash out the sludge driving a while at light trottle,gradually increasing the load,but then it even ocurred while driving at stable low speeds.The phenomenon seems to occur easiest at "throttle off" when decelerating or driving downhill,during acceleration it stays fine.So my questions are:Is it possible to use air pressure to blow the sludge out of the channels without dismantling the engine?Is this the right type of oil for my bike?Or is this simply just another type of problem,like something has coincidentally loosened from the clutch,screwing itself in and out as the throttle goes on and off,affecting the oil pressure as well?Please tell me this is a normal problem easy to sort out and that I don't have to dismantle my engine.[-o<Sincerely yours.Arve,Norway.

[Nessism]

For the oil pressure, does the light go off if you rev the engine a little? If so, the problem could be as simple as the pressure switch sticking a little. I'd just run the bike and do another oil change in 500 miles or so assuming the oil is looking black indicating sludge in the engine.

Regarding the clutch, I'd pull off the clutch cover and have a look at the whole system. Maybe the clutch basket nut has backed off (common problem) or? Also, check the cable system to make sure it's not binding (although a binding cable is not going to cause the problems you describe).

Good luck.

[SqDancerLynn1]

I would maybe change the oil filter again, Definately check the clutch basket, if the big Nut is loose it could cause problems

[bwringer]

The oil pump runs off a gear behind the clutch. I'd definitely pull the clutch cover and have a look before trying anything else.

[arve]

You were right,it was the nut in the clutch center that had loosened.Since the main gear is slightly spiral cut the clutch basket will move inwards when accelerating the engine and outwards at engine braking thereby disconnecting the oil pump gear...Thanks for your help man,i'd never figured out that alone.Since the oil lamp lit after i had added oil I was almost certain the problem was related to oil.So there you have it,it was only a weird coincidence trying to trick me.Wonder what will be next..