Harley EL four fin cylinder?

[bodnarjw]

Anyone have any thoughts or recommendations about aftermarket 4 fin knucklehead cylinders? Plenty of good and bad choices out there for the later cylinders but pickeings are slimmer fro the early ones.

Thanks for your input

Jim

[Chris Haynes]

The only four fin repops I know of are from V-Twin. Who else has them?

[INLINE4NUT]

If It Aint Hd It Aint !!!!

[Snakeoil]

I needed a 5 fin jug for my rebuild. Talked to a lot of folks who have been around this awhile and did not get any really good recommendations for repro jugs. Most said to sleeve my jugs, but the bad on I had was cracked so sleeving was not an option.

I rolled up my sleeves and started to network and actually found a NOS jug that had never been bored. I got lucky. I suggest you either sleeve your jugs or if don't have jugs, find a set that is beyond boring and have them sleeved.

[t-bone]

el jugs

i have heard teds replica cylinders are agood product from guys that have used them. as far as sleeving goes there really isnt enough material left after you have bored it out. makes for a very weak cylinder base.

[Chris Haynes]

Sleeving Knuck cylindres isn't a good idea for a rider. Cuts the meat too thin. They tend to crack in half.

[Snakeoil]

Sleeving Knuck cylindres isn't a good idea for a rider. Cuts the meat too thin. They tend to crack in half.

That's interesting. I had several individuals tell me sleeving was the way to go and they were supposed to be people that knew what they were talking about. Glad I went with a NOS jug.

[T. Cotten]

Sleeving is the absolute last resort for an impossible-to-replace casting, to be avoided if at all possible.

Four fin Knuck cylinders suffer a poor reputation without due cause:
I punched my '37s out to .110 over (mebbe it was .115?) and ran cool and smooth (until a little ol' lady in a Chrysler took me out from behind. The motor is shelved but still ready to go back into duty.)

A customer's five-fin EL bored to .155" over is still in service, nearly a decade after the motor build.

The legendary horror stories about thin cylinders resulted from poor technique, not faulty production, nor design: Proper application of torqueplates when fitting pistons would double the life of any casting.

....Cotten

[exeric]

Cotten; I was looking at old posts and came across this one. It might apply to something I want to do, but all of that is beside the point. I'd like to know where you got pistons for such a large bore, or did you make your own pistons ?

[T. Cotten]

Eric and All!

First, some reminders,

When considering huge overbores, it is also prudent to measure the remaining wall and determine any core float or bore drift from previous overhauls. This is manditory if considering a sleeve, as it will warn you of "daylight".

When performing huge overbores, the whole technique is to distort the cylinders as if installed when fitting them for pistons. This means applying stress or 'torque' plates to the cylinder for at least the honing steps.
The spigot can distort so wildly that it can bind a Sunnen if you are not carefull.
Even sleeved cylinders should be torque-plated, as they distort in their own odd manner.

This distortion is the crux of virtually all thin-cylinder overheating and fragging horror stories.

Now finally, pistons for an overbored 61" is easy: Use 10:1 compression 74" pistons.
That's the old "sixty-eight kit".

I wouldn't even bother to re-balance.

....Cotten
PS: The previously cited .155"-over machine has finally been re-built in the Chicago area, and I have yet to inspect the cylinders for results of extended duty. They could probably go another round.
I have yet to learn the maker of the replacements, but they made it to Davenport and back!

[exeric]

Thanks Cotten; the reason I asked is for a J project I'm casually working on. I have a cylinder that looks good on the outside but is badly pitted in the bore and I'm rather sure it will go to the limit to get it clean. Additionally, I want to use H-D cast iron pistons and may have to go to JD 74" pistons. I just wanted some information to put in the data bank. By the way, are there any problems with opening up ring grooves on a piston to use 2 rings in one groove ? I ask because the original cast iron pistons have bad rings and I wanted to use modern rings.

[T. Cotten]

Eric!

I have no experience with doubling up rings.
Hell, I have no experience with Js!

('xept carbs 'n' manifolds of course...)

I would just start honing until the bores were nearly clean, and then start shopping for pistons.
(For example, my .090"-over Chief project will get Continental Jeep pistons.)

The critical questions become:
How do you measure wall thickness, and what is the limit?

I measure with an altered transfer calipers as shown in the attachment;
The thinnest I have put into service were .070" remaining at the thinnest spot.

The thinnest I have observed survive duty is too thin to measure!

....Cotten

[exeric]

Great information Cotten. You make an excellent argument in favor of torque plates and I'll deffinately make one for these J cylinders.

[T. Cotten]

Incredibly, I was kicked off a forum once for endorsing torqueplates, after a resident expert declared them harmfull.

He also claimed to have designed the Gilroy "Indian PowerPlus" motor.

The same technique applies to other fits on machines, such as the main drive gear bushings in transmissions, where the sprocket and spacers should be grunted tight for sizing.

Ironically, Indian literature cites this procedure.

....Cotten

[ricmoran]

Bringing this back up again. Was looking for engine casting info and saw this because of a question on cylinders which this thread answered for me. But another quesiton came up and that is th euse of torque plates as described.

Is it best practice to use torque plates when doing 'stock' engine work? What I am driving at is will the use of torque plates provide better results as far as length of duty and longevity of rings whne used for bore/hone procedure if a bike is not ridden hard and under duress?