1919 (?) motor

[MMasa]

What book is that Tommo?
Mark

[Tommo]

The first picture is the front cover page of the book concerned.
It is a publication of a collection of Service Bulletins that were put out by the factory and cover the period from 1917 to 1926.
Mine was published in 1986 by "Antique Cycle Supply Inc., Cedar Springs, Michigan" and it says "Printed in USA"
The one we're talking about is volume one and there are volumes 2 and 3 that cover later periods.
I don't have volume 2 but I do have volume 3

[DarrinM]

The first picture is the front cover page of the book concerned.
It is a publication of a collection of Service Bulletins that were put out by the factory and cover the period from 1917 to 1926.
Mine was published in 1986 by "Antique Cycle Supply Inc., Cedar Springs, Michigan" and it says "Printed in USA"
The one we're talking about is volume one and there are volumes 2 and 3 that cover later periods.
I don't have volume 2 but I do have volume 3

I don’t see any pictures, but I’m very curious to find the books.

[Tommo]

Darrin,
Go back to the last post of mine on page 2 of this thread but here's the cover of the book for a second time 1360001.jpg

[Tommo]

I asked Mr Google if they were still available and they appear at anywhere between 25 to 55 US dollars so you should still be able to buy one.
If you're a stickler for detail, along with all the necessary fitting clearances and timing details it's the book for you.

[Speeding Big Twin]

Well, M is the factory letter code for 1924 and it seems that it’s only on the very high 1923 BN examples you’ve given.
Starting in 1924 ALL cases were large base (74” AND 61”)
The M is likely there to prevent one of these late cases from being stamped with a 1923 61” VIN.
Mark Masa

Thanks Mark.
Eric

[Tommo]

Even page 2 in the parts books tell a story.
I'll post some in order so you can see what I mean.
1912 - 1918
1913 - 1921
1917 - 1923
1920 - 1924 1370001.jpg1390001.jpg1380001.jpg1400001.jpg

[Steve Slocombe]

Dear All, looking at Speeding Big Twin's engine/belly numbers it looks like Harley used the whole alphabet including I, O and Q, so could have handled 26,000 belly numbers in a year. For the 1917 and 1919 years the belly numbers average 2000 ahead of the engine numbers, so plenty of intermediate stocks in the boom years. The 1920 Sport model has a lower belly number than the engine, but at least shows the factory were using the same belly number codes. It was a different ball game for 1922/23 with much lower production for the Brewster Green years, and three 1924 models have high 1923 belly numbers, presumably from left over stocks.

[duffeycycles]

My early 1915 has 350 belly#..my late 1915 had letter in BN.My guess is these letters first appeared in 1915

[Tommo]

Another good Kiwi mate, who is also a HD fan, has looked at his collection of crankcases and has come up with these combinations.
From 14 sets of numbers he supplied me with I've pulled out five sets of numbers that are all from 1924 in an effort to try and establish some form of progression.
HD's published production figures from 1924 are 17,648 and as they are all twins of either 61 or 74 cubic inch there is no other models to cloud the issue.

24JE 58-- E4 890
24FD 73-- G4 482
24JE 87-- I4 140
24FE 91-- I4 710
24FE 172-- P4 692

Progression of belly number letter code as against engine number all occur in a logical sequence and if you add the 1924 numbers from Speeding Big Twin things become even more logical.
Use up whats left of the 1923 cases in 1924 and then proceed with business as usual.

These are those numbers.
24JE 15-- P3 5--M
24JD 20-- P3 6--M
24FCDA 25-- Q3 8--M

If the belly number has any relationship to the engine number I find at this point I can't find a logical connection but as I've said before I'm very happy to be educated.

[Steve Slocombe]

Dear Tommo, those five 1924 engine/case numbers are within a few hundred of each other, in a year of reduced demand and perhaps more orderly factory procedures than 1917 and 1919. It all looks consistent with the belly numbers being stamped first, significant intermediate stocks, using up previous year cases on early production bikes, then a crap shoot depending on who is picking cases from the pile and maybe some requiring rework. Harley starting engine numbers at 1000 and presumably belly numbers at A1 is also going to be a complicating factor. I don't think there was a conscious effort to match engine and belly numbers, but we are observing at long distance the effect of factory stock holding decisions during periods of higher and lower demand.

[Speeding Big Twin]

Tommo, thanks for posting pages from the parts books. My earliest parts catalog is 1926–39 but I have the Volume 1 collection of bulletins you mentioned. I bought it a while ago via V-Twin Manufacturing, along with Volume Two, Volume III and Volume Four.
From H-D I bought Operation Maintenance & Specifications 1911–1930 (#99405-93), Shop Dope 1917–1949 (#99410-93) and 1930 thru 1949 Models Operation Maintenance Specifications (#99407-93).

Regarding the relationship between BNs and SNs, apparently BNs were introduced as of 1909 models and they may have completely matched the SN on purpose from then thru 1913 even though at least two formats were used for BNs/SNs over that period.
For 1914 models the second format continued, with some BNs and SNs matching completely but one example I have shows a minor difference between the two, with the SN having F at the front. This F would be consistent with the info on the pages you posted.

It may have been 1915 (?) when the BN received its next format and this continued into 1916. And for 1917-later there were other different formats for BNs and SNs.
For 1915/16-later I’d usually expect the BN, or the BN sequence portion(s), depending, to be different to the SN sequence portion but I wouldn’t be surprised to find exceptions because I’m aware of some BN sequence portions matching SN sequence portions for the 30s, 40s and 50s although it is rare. I even have an example of matching BN and SN for a 63 Pan and the numbers were confirmed by the factory.
Eric

[Speeding Big Twin]

My early 1915 has 350 belly#..my late 1915 had letter in BN.My guess is these letters first appeared in 1915

What’s the letter? And is it at the front of the BN or the end? Photos?
Eric

[duffeycycles]

Eric,I sold the later motor to Matt Smith over 10 years ago.My early '15 only has 350 belly# & the Vin is above 3100K.Maybe they started at 001 & added A1 at 1001..??? all guesses.I think my later '15 motor belly# started with C, & 3 numbers.I will try to get pics of my belly & vin for your collection.

[duffeycycles]

DSC_0146.JPGDSC_0149.JPGDSC_0153.JPG
R50 not 350 on my 1915 belly numbers