U vs UL values

[loch]

Hi Fellow Flatties,

This is not technical - my apologies.

Regarding Harley Davidson U and UL side valve machines.

Two machines, very similar in condition, and the same year, one is U model and the other a UL. Is there a difference value? Please disregard whether or not one is possibly original and the other a restoration or what a person might be willing to pay for one or the other. Assume they are the same in every respect and that each is accurate for differences between the two models. Objectively speaking, if they were sitting next to each other would the UL expect to fetch a higher price?

Regards,
Loch

[duffeycycles]

no, ULH yes

[chuckthebeatertruck]

Indeed, no functional price difference on U and UL models.

And, in my experience, there is no functional way to tell them apart from the outside. They share ALL the same parts. Same pistons, same cams, same crank, same cases, same cylinders.

What changes is the cylinder heads. The U is just over 5:1 and the UL is just over 6:1. In "theory" you could somehow use a bore scope to find the "ridges" on the heads to see what the compression ratio could be. However, even that isn't a guarantee after more than 80 years. Heads or cylinders could have been skimmed, cylinders could have been relieved. All of that impacts the ultimate compression ratio. I've seen more than one U which had what appeared to be very, very low compression due to heavy relieving.

In sum; unless you pull a cylinder head and really examine things; it can be nigh on impossible to detect the difference between the models.

The other thing that often changes is whether they are 3 speed w/ Reverse or 4 speed. Generally, unless your bike is hooked up to a side car; most people will pay a bit more for a 4 speed vs. a 3 speed bike.

But, as duffey points out; people will pay a higher premium for a UH/ULH (80" version). My own UL wore UH/ULH cylinders, alloy cylinder heads (6.9:1), and was stroked to 89.6" (rounded to 90") but from the outside looked completely like a stock 74" bike ;-)

[Jerry Wieland]

The ULH usually sells a little higher but between the U and the UL there is no difference. I personally prefer the 74" vs the 80". It is my opinion that when HD went to 80" they stretched the envelope just a little too much. When you find ULH cylinder they are always junk and usually show signs of intense heat and consequence piston failure. UL cylinders are usually in good condition.

[Steve Slocombe]

Remember the ULH models were made only 1937-41. And I see U and UL models valued as knuckleheads with the wrong engine and tanks. All the U-series bikes are fine riders but being sacrificed in search of the knucklehead dollars.

[loch]

Wow!

Thanks everyone for the concise information on the U, UL, UH and ULH.

Since a UL has recently taken up residence in our motor-cycle hall, I find it necessary to learn some more about it. I have recently been concentrating on caring for other machines that bracket the years of the UL series production.

Regards,
Loch

[Rubone]

Keep in mind there was very little difference between a U/UL and a UH/ULH. Basically just the cylinders, pistons, venturi in the carb, and on late versions alloy instead of iron heads. Most ULH were ordered by dealers with the high end packages but any could be ordered that way. To me there is no reason to pay more for a ULH,

[Steve Slocombe]

Well, let me know of any of those inexpensive ULH bikes for sale. A 1938 would be nice, but any year would do.

[chuckthebeatertruck]

Wow!

Thanks everyone for the concise information on the U, UL, UH and ULH.

Since a UL has recently taken up residence in our motor-cycle hall, I find it necessary to learn some more about it. I have recently been concentrating on caring for other machines that bracket the years of the UL series production.

Regards,
Loch

Actually, it will probably be the least fussy bike in that bracket and require little attention.

There's not much to really learn about them. Whether 74 or 80 inch - the U series is just stupidly rugged and requires no special care or attention. Make sure the oil tank is full and that's about it. There's a wide margin of safety on the valve adjustment and they are very tolerant of a wide variety of carb settings. Stock bikes seem to run out of breath around 4200 to 4500 rpm, so you're pretty much never going to over rev it and you can't float valves into the piston anyways.

In my opinion, the biggest challenge is that in stock form they do tend to need rebores/rerings every 10-15K miles and the timing bushes will wear to around .004 by 30-40K miles.

Otherwise, the only other thing most folks need to wrap their heads around is how hot the motors can get and be perfectly normal.

[Steve Slocombe]

Dear Chuck, it's interesting to me that the early ULs were like the VLs, with cast baffles under the cylinders and the forked con rod at the front. Then the rear baffles were taken out in 1939 and rods reversed and reworked, with the new strutted later 1938 pistons fitted, this time with oil rings. Have you noted differences in engine temperatures between early and later ULs? I guess I would leave out the oil rings when rebuilding early UL engines.

[chuckthebeatertruck]

Dear Chuck, it's interesting to me that the early ULs were like the VLs, with cast baffles under the cylinders and the forked con rod at the front. Then the rear baffles were taken out in 1939 and rods reversed and reworked, with the new strutted later 1938 pistons fitted, this time with oil rings. Have you noted differences in engine temperatures between early and later ULs? I guess I would leave out the oil rings when rebuilding early UL engines.

I never thought to collect this data.

indeed, there were several variations, but I’m willing to bet compression ratio made more of a difference as hd did not increase the oiling capacity. The poor “closed” rod has a minuscule amount of oil to fling.

what I have seen is that bikes running four vane pumps and 360 degree oiling seem to have the same head temperature as stock bikes, but the oil tanks actually get warm!

My ‘46 UL was pieced together and ran the early open window female rod, but in the rear position. No baffles. Modern oil control rings. It was a very, very clean running bike and consumed no oil.

Temperatures were utterly normal, with the front running hotter.

I was testing a “flywheel flinger” idea in that bike borrowed from others. I drilled two, long holes from the interior cheek of the flywheel to the rim, chamfered. The concept was that oil running out from the crank pin by centrifugal force would find its way into the drilled passages and then be “flung out” in two stripes from the rims to act as passive piston squirters when the holes aligned with the spigots each rotation.

I was in an accident with the bike before I hit 10,000 miles, so I never got to see if the idea made any difference. I know my head temperatures stayed normal but my oil temperature increased suggesting the pistons may have given up some additional heat to the flung oil.

I’m still amazed at how utterly robust the u series is. . .and flexible. It’s not hard to coax good, modern power out of them with no change in reliability.

[duffeycycles]

Kiwi Mike says to run lower octane fuel in Indian Flatty because they run cooler with less problems. They are low compression & don't need high octane.