Flywheel question

[Davereif212]

1959 FL S&S 4.25 stroke. Question is can I change connecting rods back to stock to run 74" top end or do I need to replace flywheel also. I want my girl to be back to stock. Thanks. Dave r.

[Cotten]

Dave!

Your S&S rods, although very heavy,
are perhaps "latemodel"'s .030" shorter than stock rods, which is pretty much insignificant for a street machine.

A stock top end (cylinders, heads, etc.) are installable with carefull attention, as long as the 'crown height', or distance from the wristpin to the top of the piston, will accept the extra stroke. That's usually not a problem right out of the catalog with an 80" piston. The caveat is that the cylinders must be .060" or more to accept them.

I appreciate your philosophical desire to return to "blueprint",
but frankly,
The motor only knows how well it was machined and put together.

They were under-built from the Factory,...
and from there,..
the REAL 'legend' begins.

....Cotten

[Davereif212]

Cotten, thanks for the reply. So I understand this correctly; 74" cylinders bored .060 over with 80" pistons will work if everything fits right? Dave.

[Cotten]

Dave!

I cannot stand absolutely behind anything, much less say "it will work", without the hardware in hand.
The crux of the biscuit is "everything done right".

Patience, carefull observation, double-checking all measurements, and triple-checking at installation are all variables.

But I'm pretty sure I got away with it.

....Cotten

[Davereif212]

understood, I called S&S and they do not make 80" cylinders for pans now. does anyone know of any other manufactuer the sells them? Also, is it possible to take shovel cylinders and fit the Pan head to it? Thanks.

[Cotten]

Dave!

First let me make my previous post clear that it wasn't to imply that anybody should arbitrarily use 80" pistons with 74" stroke wheels, although it would probably run great with a hack.

The importer of "big bore" and other Pan castings, as well as fine stroker pistons, is currently incommunicado.

The whole industry has suffered a setback.

Losing DIXIE will be truly the end of an era.

...Cotten

[RUBONE]

1959 FL S&S 4.25 stroke. Question is can I change connecting rods back to stock to run 74" top end or do I need to replace flywheel also. I want my girl to be back to stock. Thanks. Dave r.

If your flywheels are 4.25 stroke, changing connecting rods does absolutely nothing as per engine displacement! The only way to get to stock dimensions is changing flywheels to stock stroke.
Your connecting rods are already stock length or aftermarket equivalents!
Robbie

[steinauge]

I dont know if they still do but S&S for many years sold a 3 7\16" piston for the 41\4"stroke.It came from 37\16 to plus .090".

[kitabel]

A rather large percentage of those who "want to take it back to stock" have as their reasoning:
1. "to be more reliable"
2. "so it doesn't need as much attention"
3. "to get better mileage"

None of these factors are due to a mild stroke increase. The bike just gets slower.

[Cotten]

A rather large percentage of those who "want to take it back to stock" have as their reasoning:
1. "to be more reliable"
2. "so it doesn't need as much attention"
3. "to get better mileage"

None of these factors are due to a mild stroke increase. The bike just gets slower.

Kitabel!

No doubt there are some folks who repeat other's excuses,
but the real reason folks de-stroke is because they all stroked with lightened S&S wheels.

A set of T&O's would make them proud of their displacement.

....Cotten

[Davereif212]

Cotten, What do you think about some 74" T&O's for my 59 motor rebuild?

[RUBONE]

Cotten, What do you think about some 74" T&O's for my 59 motor rebuild?

I know this isn't addressed to me, but if you want to go stock stroke there are plenty of H-D flywheels out there and they work just fine.
Robbie

[kitabel]

I agree - for most people the nervous behavior of light wheels is more trouble than it's worth. I normally recommend TorqueMonsters in either 4-1/4 or 4/1/2.

[Cotten]

T&O's are finely engineered and machined, and delightful to assemble and balance, as well as ride.

And as Kitabel mentioned, 4.5" is a mild stroke!

....Cotten

[Davereif212]

Thanks