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Oil Pressure

Spaceman49

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Good Morning. I have a 1970 CB750K0. I have recently done a total over-haul on the engine and have around 480 miles on the engine. It run's great ( though I am having a little trouble dialing the carb's in. But I think that is normal for old carbs.). I began to see the oil pressure light coming on at idle. The first thing I did was change the oil and filter. I tore the filter apart to see if there was excess metal or material in the filter causing a blockage. The filter was clean. Next I removed the oil pressure switch and put a pressure gauge with a capillary tube on and taped the gauge between my tack and speedo. I rode the bike for about an hour. The oil pressure started at around 65psi. After about 15 minutes it dropped to 60psi and stayed there for the rest of the run. When I got home and let it idle the pressure dropped to about 20psi. I have a feeling that I have an enternal problem.

When I had the engine apart I made sure to swab out all of the oil passages and channels and then blow them out with air to insure clear passages. I double-checked that all "O" rings were in place as I stacked the jug's and head.

I am afraid that I may have worn cam tower's or something. Other-wise am at a loss.

Any suggestions
 
Those pressures are absolutely normal. 20 psi at idle is actually very good. The oil light doesn't come on till 7 psi. Oil weights will have an effect on oil pressure but the relief is set at 60 psi max pressure at operating temp.
 
Thank you Sir. I have ordered a new pressure switch cause I think that is the problem. Also, as I remember, running 40 or 50 weight might make a difference. Thanks again and hope I can return the favor dirt digger.
 
In a stock motor run 10-40 not a straight weight oil. If it is always hot and you run the crap out of it or it is a big bore run 20-50 but 10-40 is the all around oil. Straight weight oils really have no place in a plain bearing overhead cam motor, especially not with the clearances in these motors. You really need the thinness of a multi weight to make sure the top end gets oil right away on start ups.
 
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