Ul cylinders - are there any out there?

[Paul James]

Recently I had my front cylinder separate from its base putting an end to a nice sunday ride. I never thought much about the scarcity of parts for my 1946 ul 80 in. until this episode. I had read with interest that S&S was casting and machining replacement cylinders for the large flathead. I thought this would make things easy and that I could just go out and order some of those nice looking spare parts. However, after a few calls, I realized this is going to be a lot tougher than it looks.

Does anyone have a solution to 80 in. flathead cylinders. Mine broke apart from fatigue and a poorly centered overbore job that left one side very thin. The base is intact and the upper portion with fins. The lower barrel disintegrated from the piston action so there is nothing left to sleeve into. My rear cylinder is fine and the rest of the motor is in good shape. I need a front Cylinder.

I have heard that the newly made up units can vary in quality and that the iron in the casting can be too soft. Does anyone have any experience with these new cylinders. Are the Dixie cylinders better than the S&S? As an alternative can a maxxed out 74 or 80 inch cylinder be sleeved and restored for further use?

I would like to hear from members who have confronted this problem about how they fixed it. If there is already a thread in the archives perhaps some one can direct me too it.

Thanks much

Paul James

[Steve Slocombe]

Dear Paul, your 1946 UL should be a 74 as standard, as the 80 inchers were made only 1937-41. The 80 inch front cylinder would have casting number 120-37 in the base flange and the 74 cylinder would be 120-38. I have one original 74 front cylinder bought years ago and mistaken for a 1936 VL cylinder. Contact me off this bulletin board if interested.

[duffeycycles]

11 fin and 13 fin

[Jerry Wieland]

I do not believe there is anything that can be done for your busted cylinder - it's a wall hanger - at least I would not run a massively repaired cylinder on the top of my good cases. I have a friend who ordered a set of V twin cylinders and when he got them the one intake threaded nipple was .100" higher than the other when set on the cases so he bought a set of S&S Flathead Power cylinders and although he hasn't run it yet he said they looked good and fit the cases perfectly and he hopes to be running shortly.

It has always been my opinion that when HD took their big flathead to 80" that they stretched the edge of the envelope just a tad too much. All OEM 80" cylinders were 13 fins and yours if stock should have been 11 fin. However, I do not believe that the 13 fins cylinders were any better at 80" than your 11 fins apparently were. Usually when a HD busts a cylinder you can find reasons as to why it happened. Air leaks, point gap off causing timing issues or in your case, bad machining.

All that said the cylinders are out there - just not cheap. I would run a sleeved cylinder only as a last resort.

Jerry

[Robert Luland]

OK guys, I's got a question? My 37 rear cylinder is casted 120-371. 13 fin, releaved valve ports. Anyone?

[duffeycycles]

1937 UL cylinders were 13 fin bored to 74"-
in 1938 they made the 11 fin UL 74"cylinders and the 13 fin became the ULH 80" cylinders-
I don't remember casting #s
The relieved ports could have been modified,I believe that Sifton raced relieved ports in '37 and did not disclose that info to harley until he had won all his races for the year-1938 HD was the first factory relieved port jobs
many were modified later?

[Jerry Wieland]

OK guys, I's got a question? My 37 rear cylinder is casted 120-371. 13 fin, releaved valve ports. Anyone?

I do not have the numbers memorized but it sounds like an OEM UH or ULH rear cylinder. 1937 and 1938 UL & ULH cylinders were the same casting. The ULH's were just relieved around the valves and bored to 3 7/16" instead of 3 5/16". U and UL cylinders were not relieved.

Jerry

[Kozy]

11 fin 74" cyl. casting nos. 120-38 front, 120-381 rear

[Steve Slocombe]

And 13 fin 80" cyl. casting nos. 120-37 front and 120-371 rear. The 80" cylinders for the UH and ULH would have been relieved as described above. Presumably the 1937 74" cylinders were not relieved. So for 1937 only the same cylinders were used on the 74 and 80 inch flatheads, with the 80s being bored for 3 7/16" rather than 3 5/16" pistons. This may have meant poor heat transfer on the 1937 74s with thick cylinder walls, or maybe Harley just wanted to save a dollar in the castings.

[Paul James]

Thanks for all the replies to this thread. A recent update follows. I have found cylinders for my ul. The S&S cylinders remaining stocks have been bought up by W&W in germany. I have ordered a set with pistons and will be finalizing the transaction tomorrow. I will post when they have been received and after we assemble the engine. Perhaps there is a solution to thin walled 80 in. cylinders on the verge of destruction. Stay tuned. W&W can be reached at wwag.com. There motto is: A bikers work is never done. SO it seems!

[Paul James]

Ok, we have received the cylinders and everything looks good. They are 74 inch not 80 inch. I don't care at this point. I would rather have something solid to run with. It looks as though my flatty will live again. I will post again after assembly. On first measure everything looks good. Costs w shipping for the set of cylinders, pistons, valves was just a little over 2000.00. These motors are not cheap!

[Kozy]

Has S&S given up on BT flathead cylinders and heads?

[Early Iron MC]

Yes S&S is not going to produce the flathead cylinders any more, not sure about the heads yet.

[Dan Lovallo]

Question?

Yes S&S is not going to produce the flathead cylinders any more, not sure about the heads yet.

I have a question? I'm looking at a 1937 ul motor with 13 fin cylinders. The casting is 120-37. Is it possible for those to be either 74 or 80 cubic inch? Or is that casting definitely 80ci?

[Sargehere]

120-37 is a 1937 front "U" cylinder. They are thick-walled, and were used on both 74s and 80s in 1937. Which meant if you had bought a U or UL 74 you could build it right through abt to about 3 7/16" +.070 ULH sizes using those cylinders. When you hit 3 7/6" you could install a Linkert M51L in place of the M51 and be right up to speed for the engine displacement.