1961 Panhead questions

[Rmcalister]

I'm just getting round to putting a 1961 Duoglide Panhead together - I'm trying to get it a little closer to standard but not aiming my sights too high. When I bought I was a bit dazzled and as Sportsters have been more my thing I didn't clock all of the issues. The bike was advertised as an ex Police bike possibly - well it has a hand shift with police inscribed on it. It does not have the square oil tank or any sirens ( I have one now).

One of the things I want to put back to original is the cylinders - the bike has good 61 cases with matching belly numbers so all good there. The heads though were off a 48 and I have replaced these with some off a 61. I am still looking for some 61 cylinders, the ones on it are repo. This is where my knowledge starts to break down - cylinder identification and date codes have been a bit of a minefield.... my understanding is that I am looking for a date code with x-1 or x-o (x being the month 1 and 0 equating to 1960 or 1961; though could also be 50 and 51?). I think that I am also looking for cylinders with that date code with a drain internally at the bottom of the cylinder) any thoughts on the cylinders appreciated.. I have put an ad in the wanted section for set of 1960 - 61 cylinders - sadly not takers yet - message me if you have some in reasonable condition - ( don't mind re-sleeving and minor repairs to fins),

The other thing that I'm looking to understand a bit better is the regulator mount - the bike came with a solid state one which was really unseemly. I've managed to get hold of a mount however am not sure how and where it mounts - also can a 12v regulator be mounted to this rather than the 6v one - any photos of how this is supposed to be mounted on a Duoglide would be appreciated - i'm not seeing much in the online workshop manuals.

[Rubone]

Original '50 and '51 cylinders differ from '60-'61. The oil drain holes are different and they do not interchange without some machine work. Don't hurt your brain.
Regulator mounts on civilian Duo-Glides mount on the rear motor mount and the regulator is on the right near the exhaust. Police Duo-Glides have a larger regulator mounted outboard of the ignition coils on a special mount and extended studs. What are you trying to do?. Which generator is on your bike?

[Rmcalister]

Thanks for getting back to me .. the generator is a 12v and I'm wanting to stick wit that but have an authentic look.

In regards to the cylinders I'm not sure exactly what I have .. if you could have a look at the photos and advise. Living in the UK I don't really have access to other Panheads for reference and what swapmeets there are near me don't have Harley parts.

[Speeding Big Twin]

my understanding is that I am looking for a date code with x-1 or x-o (x being the month 1 and 0 equating to 1960 or 1961; though could also be 50 and 51?). I think that I am also looking for cylinders with that date code with a drain internally at the bottom of the cylinder) any thoughts on the cylinders appreciated.

Front date code looks like L 16-0. If so it indicates casting on November 16 of 1960 or 1950. L indicates November because the letter I was skipped in date codes for Pan cylinders.

Re the drain hole in the bore, it was original for 53–65 model Pan cylinders. No drain hole in the bore as original for 48–52 model Pan cylinders. Your cylinder looks like it has a drain hole in the bore but it doesn’t necessarily indicate 1960 as opposed to 1950 because anyone could drill a hole in the bore of a 48–52 model cylinder that didn’t originally have one.

What does the top fin look like at the front? Is there a straight section like the cylinder below which was cast on October 3, 1950?







Or is there a curved relief like the next cylinder which was cast on September 13, 1954?








I used that second picture because it shows the relief more clearly than on some other cylinders but I think the curved relief may have been introduced during November 51. But please look closely at your cylinder because sometimes people alter the early style (straight) top fin to make it look like the later type and sometimes this may have been done after the fin was damaged/broken. If yours has that curved relief check it closely to see if it looks original.

Also check the R-H side of your front cylinder for a boss as per the next picture. On Pan cylinders (front and rear) it was something that only appeared in 1950 casting and apparently only in certain months, AFAIK. It seems to have been omitted during October 50 though so I don’t think your cylinder will have it but we may as well check. Even if at first glance it doesn’t seem to be present, look closely because sometimes it was removed and I imagine that was done for cosmetic purposes.







Your rear cylinder date code looks like B 15-1? If so it indicates casting on February 15 of 1961 or 1951. Obviously if it has no drain hole in the bore then its absence may suggest 1951 as opposed to 1961. If a drain hole in the bore is present then it may suggest 1961 as opposed to 1951 but the hole, or lack thereof, is not a definite means of ID.
Eric

[Rmcalister]

Speeding Twin -What does the top fin look like at the front? Is there a straight section like the cylinder below which was cast on October 3, 1950?

Thanks - that was a really helpful - the front cylinder does have the curved section as identified in your picture - so I believe this is a 1960 cylinder.

The rear one I think must be 51 as it doesn't have an internal drain hole and I don't think that it has been filled in - do some get filled in if the motor has been stroked?

Anyway I'm still in the hunt for a 61 rear cylinder - are there any other identifiers for a rear 1961 cylinder as opposed to the 51 - do the rear 61 ones also have the curved relief section?

One more question .. in terms of the external spigot diameters are these the same through the years?

Once again thanks for your help - this is a little bit more difficult than I had imagined....!

[Speeding Big Twin]

You're welcome. If your front cylinder has the curved relief, and if the relief looks original, I agree the cylinder was cast in 1960 as opposed to 1950.

Regarding the rear cylinder and as I mentioned above, if no drain hole in the bore then its absence may suggest 1951 as opposed to 1961. But also as I mentioned, lack of the drain hole is not a definite means of ID. For example imagine someone has a cylinder that was cast on Feb 15, 1961 but 48–52 model cases are being used. The cylinder would have had a hole in the bore as original but what if the cylinder needed re-sleeving? If it did, a new drain hole could be drilled although it wouldn’t necessarily be required due to the cases being 48–52. If a new hole wasn’t drilled then the cylinder could be mistaken for one that was cast on Feb 15, 1951.

Before posting yesterday I went through my folder but couldn’t find anything else to help separate 74ci rear cylinders appearing to have been cast in early-51 from 74ci rear cylinders appearing to have been cast in early-61. Sometimes, depending on calendar year and even at times depending on month, there are clues regarding the size of the letter and the size and type of the DC plate but unfortunately these characteristics for early-61 casting seem to have been the same as they were for early-51 casting.

And I didn’t do any better when I compared late-50 casting against late-60 casting as far as letters and DC plates on 74ci rear cylinders are concerned. (If we were comparing early-50 casting with early-60 casting then I’d be tempted to comment on the size of the plates.) Four other things relating to 74ci rear cylinders don’t help on this occasion either because the earliest of them occurred after mid-61 (calendar year).

Returning to the bosses on the R-H side at the base, these are only found on cylinders cast in 1950 as I mentioned earlier. On 74ci rear cylinders so far I’ve seen them for June, August and September and they may have also continued into the first few days of October like they did on 74ci front cylinders.

I haven’t seen a Pan rear cylinder with a curved relief as original for exhaust pipe clearance. Or one with a straight section either. I have one example of a curved relief on a Pan rear cylinder but I don’t think it was done at the foundry or by H-D. Instead it may have been done by an owner and possibly even after some damage occurred. Plenty of Pan rear cylinders have their top fin damaged/broken in that area.

As for spigot diameters, AFAIK they were the same for Pans 48–65.
Eric

[ammorest]

Not all Police bikes used the "square" oil tank. It was used on radio equipped bikes that required a large battery. It is quite an ordeal to convert to that setup. I converted a 1960 Duo-Glide civilian bike with a foot shift to a radio Police bike with a hand shift and square oil tank.
First, do you have the correct square oil tank? The rigid frame tank has a screw in cap and the Duo-Glide tank has a large twist on cap with an oil filter. The oil pipes are different between the two also. There is a bracket that connects the rear chainguard to the oil tank mounting plate. A big problem is the battery. as far as I know the correct type battery is not reproduced. I was lucky enough to find an old one that was gutted out for a sealed battery. I fabricated terminals to look original. Maybe you could make something that would wok.
To make it look original you will have to mount the voltage regulator outboard of the coil. It mounts on a rubber mounted bracket on two long studs that hole the coil to the frame. Since it is 12 volt what coil are you using? If you decide to not go with the square oil tank setup you could use the Duo-Glide voltage regulator bracket; an L shaped bracket that mounts under the rear motor mount bolts. To retain the original look there is a gentleman in Minnesota (maybe Wisconsin) that converts the 58-64 voltage regulator to 12 volt solid state. Another option is to use the Bosch voltage regulator that is used on early Sportsters with 12 volt.
Hope this helps with your decisions.
Dave