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Discussion Starter #1
I just put an oil pressure gauge on my '98 Road King. The bike has 11,400 miles on it. The pressure gauge registers about 11lbs at a hot idle and jumps to 20 lbs. with a quick throttle twist.

This seems low to me. The bike runs great.

Thanks
 

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I {Heart} Hookers.
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Nope. Perfectly normal. Repair Manual gives specs of 7-35 psi range. Evo doesn't need oil pressure so much as oil presence. Only the tappets rely on high pressure, and the passages up the pushrods, into and through the rocker shafts. That's it....

Mine runs 23 highway (hot) and 15 idle. On really HOT days, I'll see 18 highway and 8-9 at idle.
 

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The Evo doesn't have a crankcase. For the oil to run back to the tank it would have to run up hill, when you shut the engine off the oil stays right where its at. I don't know about S&S pumps, but the stock one has a filter screen in it. Its located right on top of the pump. It should be cleaned, their is a spring around the screen that we used to stretch a little bit to boost the oil pressure. Maybe S&S has the same on their pumps. Hope that helps.
 

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I {Heart} Hookers.
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...their is a spring around the screen that we used to stretch a little bit to boost the oil pressure.
The spring isn't at the oil screen, (oil screen is in the boock) it's under a cap on the oil pump that covers the oil pressure relief valve.

The increased spring pressure raises the amount of oil pressure needed to lift the slide and allow oil to the bottom end. This results in increase oil pressure to the top end at idle.

What it does is forces all the oil to the lifters and the top end.

When the amount of oil directed to the lifters cannot pass through the lifters and the top end, it builds up pressure and raises the slide allowing oil to flow to the connecting rod bearings.

In a hot motor at idle, the oil flows through the top end and doesn't build enough pressure to lift the slide, thus depriving your bottom end from receiving oil.

The stock spring was designed to balance the needs of the top and bottom end oiling requirements. In the good ole' days, people would remove the stock spring and stretch it. Then your guess was as good as anyones as to when it opened.

The spring is used to compensate for other problems. As mentioned above, rocker arm bushings, lifters, pump body scoring, worn pump gears and lifter blocks are more than likely the cause.

I don't recommend simply stretching the spring.............
 

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Discussion Starter #5
Thanks for the info, Dave.

I know it's probably also normal to hear a tapping while cruising along. I assume it's the valves tapping. Should I hear this or does it indicate the top end is being starved for oil? Thanks.
 

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I {Heart} Hookers.
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You may have a weak lifter. (Tappet) The front exhaust tappet is the most common to go, as it's angle and distance from the pump. HD recommends replacement at 25K. Excessive pinion/cam gear lash can cause the same noise.....

Make sure it's not an exhaust leak at the pipe/head too. They can be deceiving.
 

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Winter before last I spent out in the shop doing a major overhaul (not the motor, the bike) on my old '89 Heritage with app. 85,000 miles. The motor has been tore into a couple of times for upgrades and is a solid Stage One. New tires, brakes, suspension, belt and sprockets, primary, clutch, starter, bars, paint... and it turned out pretty good.
Anyway, I got it out in the spring and took a few rides and everything was cool. 4th of July I head on down to the hot springs in Thermop for a good soak (it was an overcast, cool day for July). I probably should have let it warm a little more before I got on the throttle but that became evident 25 miles down the road when I pulled over to get rid of the morning coffee. I pulled over and my bike wouldn't idle down, that's when I looked down and saw all the oil on my chaps and right boot. Hitchhiked back and got my tire truck and made a recovery and had the bike home by noon. Getting back to the house I found I had blown a line not a hundred yards out of the driveway and ALL the oil gushed out. Turns out I had crossed up a couple of oil lines when I'd replaced them the winter before. I'd changed the oil and used my customary Mobil 1 V twin oil and it was fresh so this is what I attribute my survival to. I took my bike up to Custom Cycle in Cody and had Ray tear into it in the fall and he found nothing wrong in the top end, let alone anywhere else. He did recrosshatch the pistons , install new rings and slap new lifters in as they had just the slightest bit of scoring on them. Ray said stranger things have occurred and the Evo is one tough chunka iron.
I've got the rings seated and it runs as good now as ever, and carries 15psi oil pressure hot, which sounds like is right in there as that was the reason for coming to this forum.
 

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Just Ride
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About right. You may want to start your own thread. This one is 9 years old.
 
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