youtube with morning coffee

[billbeemer]

so I'm perusing youtube looking at harley engines.  why do the crankshaft flywheels have plugs in them.  some discussion about welding or no,  why are they there in the first place?

[Ohio HD]

Expansion of the pin into the flywheel.

[Admiral Akbar]

First place? To seal the hole in the crank pin so that the oil can get to the rod bearing.

[Paniolo]

I had mine pinned and welded.

[PoorUB]

First place? To seal the hole in the crank pin so that the oil can get to the rod bearing.

We have a winner!!

[Ohio HD]

We have a winner!!

It does both, expansion maybe not so much for OEM. At S&S and DH it does help hold the pin from slipping.

[PoorUB]

I agree with the after market, but the OEM plug just help send the oil the correct direction so that answer covers pretty much all of them.

[billbeemer]

call me stupid,  I don't get it.  a plug in the flywheels so oil can get to the crankpin?  huh?

[1FSTRK]

HD went to a large diameter hollow crank pin. Unlike a hollow car crank they feel oil into the hollow center then out to the bearings through drilled passages. Then they press plugs into each end to keep the oil in the hollow center space.

[billbeemer]

I'm getting there, but still confused.  what path does the oil take from pump to crankpin?  are u saying it flows inside the flywheels? 

[Ohio HD]

Oil flows through the pinion shaft from the oil pump and cam plate, through the flywheel, into the crank pin. HD's have oiled this way since the beginning, except that the oil pump was not under the cam cover on pre Twin Cam bikes, it was outside the case, rear of the cam.

[1FSTRK]

Look here

[FSG]

that's why you shouldn't point, it pokes holes and the air gets out   

[1FSTRK]

Thanks FSG
I was not sure if it was ok to post the pic here so I just posted the pic address.
I will know better next time.

Added
I bet you have a pic of one with a press in hollow pin so he can really see how the M-8 looks.

[FSG]

    I just put [img width=800 height=420 ] [ /img]  tags around your link 

specifying the width and height ensures it doesn't blow off the screen, but you can click on the image for the full size

[billbeemer]

thanks guys................a lot clearer now.

[FSG]

there are plugs and then there are plugs   

some (the HD variety) do nothing more than seal the ends of the crank pin and in essence are nothing more than a welsh plug / freeze plug similar to what you'd find in your cars engine block

the aftermarket plugs used by the crankshaft builders/rebuilders are a solid plug which are pressed in with a lot of force and in doing so expand the end of the crank pin into the flywheel

[FSG]

and there's this crank, it's a TC Softail Crank, weld well no comment there, notice the welsh type plug   

[billbeemer]

i understand oil goes into flywheel and into crankpin for lubrication of rod bearings ...............but how does oil get to drive side pinion bearings and such?

[PoorUB]

The main bearings are splash lube, as are the inner cam bearings.