Update and question 1947

[CAP'N BOB]

Good morning:

1947 FL update.

Could not get consistent pressure with the stock pump so went back to an S&S pump. This S&S pump is made for their KN and has lower oil pressure.

Put the .063 inch drilled clutch rivet into the gear cover to feed the top end. Based on oil drip out of the overhead oil line to the fittings feeding the rocker boxes, that seems to be working. Do not have oil dripping out of the top end, now.

Drilled the .055 inch hole in the front intake tin, the tin that is really for a rear exhaust, so now both intake tins have .055 inch holes.

Put clear oil lines on the system, and can see oil moving.

Put an oil pressure gauge on, along with the oil pressure indicator light, and have 30+ PSI.

Have not yet put the tanks back on, have run the knuck several times with the gas bottle. Bike starts, runs nicely, and oil moves. No drips from the rocker box nuts, which I had before, and no oil pouring out of various top end places.

The question: Now that this engine, which I’ve had since about 1993 and it always leaked from the top end, no longer leaks (at least, on the lift with the gas bottle) from the top end, how am I supposed to know if the .063 inch drilled hole in the clutch hub rivet in the gear case is allowing enough oil to the top end? I know this is a really bizarre question, considering this whole thing started because I was trying to REDUCE top end oil leaks. Now, though, I’m paranoid about not enough oil.

So, any guidance before I put the tanks back on and put this back on the road will be very much appreciated.

Bob

[Rubone]

Top end oil leaks are primarily a product of lack of a vacuum tight seal on the pushrod covers and top tins, and have little to do with oil pressure. ANY S&S or Shovel pump will over oil a Knuckle, reduced pressure or not. The stock system works on volume, not pressure and having a high pressure at a gauge means very little. There is no need to regulate top end oil on a stock system that is sealed properly, but the volume needed was a function of the stock pump design, so any change to that system is a crap shoot. But it doesn't matter how much it is regulated and how much you can pump if the system as designed cannot scavenge it by vacuum. The breather gear, case drillings, cam cover gasket, tappet guides and blocks, pushrod seals, rocker box seals, and return pipe connections are what keep them leak free.

[CAP'N BOB]

Thank you, Robbie.

When you said the S&S pump will over oil a knuck do you mean top end and everywhere? Would the combustion chamber and gear case be impacted by that?

I now understand the vacuum issue, having read a number of posts and having had that explained to me. That is why I drilled the .055” hole in the front intake tin, which, on my bike is really a rear exhaust tin, as pointed out by KnuckleheadTim.

I’ve never worked on a knucklehead and only own this one, so have a lot to learn.

How do I KNOW there is adequate vacuum? Only by the amount or lack of leak? If there is no leaking, how do I know there is any oil in the top end?

With the stock pump, I had pressure and then not. I know you said pressure is not the issue, but if I cannot see oil moving in the clear lines and/or returning to the tank at high idle, that cannot be good, right? If the oil indicator (idiot) light comes on and stays on and the oil pressure gauge (valid to have or not) drops to zero, that cannot be good, can it?

Is it possible the stock pump races or gears are worn and not moving a proper amount of oil?

With the S&S pump, I see oil moving, not in a steady flow, but in pulses. I assume (terrible word) that is proper. I have the S&S breather gear that was developed to help scavenge knucks, all is timed properly, the bike starts and runs easily, once warmed up, holds idle with no trouble and the oil moves through the entire system-feed to pump, return to oil cooler to oil filter to oil tank, I can see it pulsing and moving.

I’m not opposed to removing the new S&S pump and putting the stock pump in, again, but somehow have to know that the pump is moving oil and not also pouring it out the top. Of course, since the front intake was not drilled before, maybe all I need to do is run it and see what happens, now that the tin is drilled.

The above is long, but if you have gotten this far, does Over oiling mean I will have white smoking exhaust because there is too much oil in the combustion chamber? Or, does it only mean there will be too much oil at the top end? And if only at the top end, will the restrictor I put in help with that problem?

Thank you for your forbearance on this issue of helping me with the knuck.

Bob

[kg993]

I can't really help with your questions but do want to mention that the stock pumps need oem thickness gaskets to keep them pumping at low speed with the motor warmed up. Most after market gaskets are extra thick. And the width of the gears make a difference too.

[CAP'N BOB]

Thank you, Kerry.

My Mistake: Since I was having trouble getting the gears to move smoothly while tightening the pump upon installation, I "shimmed" the pump by adding extra gaskets. That worked by letting the gears move smoothly during installation and there was pressure and oil movement, Until the oil was warm, when oil pressure and movement dropped out. So, that certainly lends credence to your message. Thank you.

Since I have the S&S pump on the '47 and oil moves, I'm going to put the tanks on and ride the bike. If all is well, it will work. If all is not well, I can put the stock pump back on and try that, again. I'm getting REALLY good at taking this apart and putting it back together!

Bob

[knuckleheadtim]

As kg993 mentioned, aftermarket gaskets are too thick. Stock are about .007" and replacement are often .020" thick. This is equivalent to drilling a 1/8" hole to nowhere in you pump!

[CAP'N BOB]

As kg993 mentioned, aftermarket gaskets are too thick. Stock are about .007" and replacement are often .020" thick. This is equivalent to drilling a 1/8" hole to nowhere in you pump!

Thank you.

Where would I get basically stock gaskets? I get mine from V-Twin, but did not measure them. The two outside gaskets were very thin, but the inside (up against the gear case) is much thicker than the two cover gaskets.

[knuckleheadtim]

Amazingly, I was still able to get some from a dealer a few years back, but it's unlikely now. In a pinch, you can glue them to a surface grinder and take them down to size! Use a little lacquer thinner or a razor to remove after. It sounds totally ridiculous, but works well.