Going back to the way it was

[jehagadone]

The 52 four is running.
There were some problems getting it to go after resting 62 years.
There are two high pressure oil lines, both were leaking, oil was flying.
Come and listen to my story about a man named Jed
A poor mountaineer barely kept his family fed
And then one day he was shootin at some food
And up through the ground come a bubblin crude
Oil that is black gold Texas tea

Ride up and down the road, fix a few things, ride up and down the road, fix a few things.
First impressions, bike has some power, pretty cool in 52.
These bikes are rare in usa, never saw one on the road.
More reports when I can ride further.

[nevhunter]

IF it's done miles and then sat, I'd strip it and remove the crankshaft plugs and carefully desludge the Crank. If you don't you can chuck the left side rear rod through the case. It's happened a lot. Nev

[SEDoan]

That is a cool looking bike. For some reason the twin exhaust Sq4 looks better than the 4-piper to me. I'd leave it just the way it is, but Nev is right they have a terrible reputation for wrecking rods and crankcases so the engine should come out. I know a guy who's had his since the 1970s and he just got done fixing his for the second time! A Sq4 expert in California said that something like 60% of the Sq4s he'd worked on had through a rod!

I wonder, has anyone tried drilling out the crank oil passages larger so they are less likely to clog?

[nevhunter]

The Grunge centrifuges and can come loose later. The twins require it also. nev

[paul.jameson]

The facts are simple. Old fashioned engine oil without detergent coats the insides of the engine with black gunge. Modern oils which all contain detergents wash the black gunge off which then fills up the sludge traps and blocks them. Changing to modern oils, any time from about 1970 onwards, gives you about 500 miles before the engine throws a rod.

So unless the engine has been stripped and all engine parts cleaned to near clinical standards, along with cleaning out of the sludge traps and fitting of a modern filter in the oil return line, you can expect your engine to blow up within 500 miles.

From time to time, people ignore this advice. Then another set of Square Four crankcases is destroyed.

[simon.holyfield]

This is what it looks like. That black clay-like plug goes all the way to the #4 big end oil way - fortunately, this engine was stripped and cleaned following advice on this forum and has performed beautifully ever since - about 4500 miles now.

[Vincent.vanGinneke]

is this a before picture ?
as it looks like there are no rocker spindles...

(pic on top of this thread)

[nevhunter]

That plug is staked in. Easier to remove if the staked bits are ground away first so the thread is not fouled. Drilling them out is not fun. Avoid the need if possible. A sharp crack with an engineers Hammer on a brass drift on the face of the plug can help to start it moving. Nev

[simon.holyfield]

is this a before picture ?
as it looks like there are no rocker spindles...

(pic on top of this thread)

Are the barrel flange nuts missing as well?

[nevhunter]

I'm confused. That's an alloy Connecting rod fitted to a crank throw. Nev