rev.1 52-72 k & xl frame model year determination flow · pdf file3 hollow footpegs believe...

OSKRG Research/Restoration Bulletin #1REV.1 52-72 K & XL Frame Model Year
Determination Flow Chart
This research and restoration bulleting was created with input and assistance from members of the OSKRG. The report consolidates the best available information at the time of creation and may be updated or revised at a future date. If errors are identified, or there is additional information on the subject of this report that has not been included, please send corrections or additions to:
[email protected] & [email protected]
1 Copyright OSKRG 2014
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]

Generic Frame 52-72 K & XL
52-56 K Model See Slide 3
57-66 XL, XLC, XLH & XLCH See Slide 13. (Small Hole)
67-72 XLH & XLCH See Slide 20. (Big Hole)
52-72 K & XL Frame Model Year Determination Flow Chart Vs.6
Note: Years denote approximate model years since some changes were running changes.
2 Copyright OSKRG 2014

3
Hollow footpegs believe used only on 52 & 53K models. 53K also used solid footpeg frames with & without frame date codes. Believe all 52 & 53Ks used non-welded 52 neck casting frames.
Solid footpegs first known date code May 53. Am aware of a non date coded frame with solid footpegs. Believe almost all 54Ks were frame date coded & had solid footpegs. Believe all had welded neck 52 neck castings or 52A neck castings
Earliest 52 frame had welded on steel fender strut supports. This original seat casting with the welded fender strut supports has two versions, see pages 4, 5 & 6.
Cast fender strut believe used later 52 & on for all K models.
Early & late welded 52 Neck Casting, earliest vs. known June 53 frame code, earliest later vs. known August 53 latest known September 54. Several exist pre frame date Code. Believe correct for 54K & early 55K model.
52 Neck Casting, earliest date code known E3 latest F3. Believe correct for all 52 & 53K Models.
52A Neck Casting, earliest known Oct. 53 latest December 54. Believe correct for later 54K models & early 55K models.
55 Neck Casting, only know of several with frame dates of April & May of 55. Believe for now that 52A & welded 52 Neck Casting frames were used for early 55K models, to what VIN unclear.
Late 56 Neck Casting with Stem Ridge, used on 56K models & XLs. Earliest known D6.
52-56 K Model Frames
Early 56K Neck Casting without Stem Ridge latest known A6.
Copyright OSKRG 2014

52-56 K Model Notes
Copyright OSKRG 2014 4
Original 52K frame shown on top left had threaded rear downtubes to accommodate threaded Seat Post Bushing Sleeves shown on lower left. The top right picture shows the later welded strut seat casting smooth rear downtubes that the rest of the K frames had along with the non-threaded smooth Seat Post Bushing Sleeves.

52-56 K Model Notes
This picture shows side by side the earliest threaded rear downtube K frame next to the later smooth rear downtube frame both with the early welded strut seat castings. I believe the reason for the threaded seat post bushing sleeves on the earliest frame had to do with a design error of the seat casting . Specifically the area above the seat castings BH (Butt Hole) shown by the yellow arrows. See page 6 for more details.

The yellow arrow on left shows a steeper slope area above the seat casting BH on top left picture. The yellow arrow on the top right picture shows the more gradual slope above the BH allowing proper fit of the Seat Post Retaining Plate.
Pictures on the left middle and bottom show that the Seat Post Retaining Plate does not fit on the earliest K frame . The frames backbone interferes with it laying flat necessitating the need for an alternative method to hold the Seat Post Bushing Sleeves in place, threading them. The pictures on the right middle and bottom show the Seat Post Retaining Plate properly fitting due to the greater clearance achieved by the more gradual slope cut on the backbone.

52-56 K Model Notes
7
Note 1, 55 & 56 neck casting frames have the reinforced down tubes. Yellow arrow.
Note 3. Earliest 52 seat casting (yellow arrow), welded on fender strut supports, thinner than 52-55. Mid 52 through 55 seat casting (red arrow), has cast fender struts, is thinner than 56. 56 has thicker seat casting (blue arrow).
Note 2. 52 through 54 frames have 5/16 course threaded coil mount bosses. 55, 56 and on have 3/8 fine threaded bosses (yellow arrows). 52A neck casting frames & 52 welded neck casting frames used on 54Ks have the 5/16 coarse treads. 52A & 52 welded neck frames used on 55Ks have the 3/8 fine thread coil bosses.
Note 4. Smashed underside of backbone to make room for 57XL rocker boxes (green arrow). Believe L5 to be last non smashed underside and A6 to be first smashed underside.
Note 5. Some K model top motor mounts have casting numbers. I have been unable to discern a pattern based on frame date. I believe difference is due to two different providers.

8
52-56 K Model Notes
Note 6 Frame Steel
1952 1953 1954 1955 1956
Mild Steel C 1026 X X X
Chrome Moly X ?
The September of 1954 Enthusiast magazine indicates that the 55 K frames will be Chrome Moly steel as a new feature. Cannot locate documentation indicating frame steel type for the rest of the K & XL frames. Because the 54 Enthusiast indicates the Chrome Moly as new for 55 I believe the earlier models are not Chrome Moly. 1956 and later XL frame steel is unknown at this time.
Note 7. Earliest 52 swingarms have longer tubes than 53 and later, yellow arrow, although overall length is the same. 52 has squared corners, see red arrow. Dont know if this was a running change in 52 or not. There are definitely 3 distinctly different swingarms for the K model, possible 4.
Note 8. Believe the earliest K frame left side footpeg bracket has a hole in it, see red arrow, it soon was cast over, see yellow arrow. Believe to be cast over by very early 52. It should be noted that Eric K has an early welded fender strut support K frame that has the footpeg hole cast over. We Know that the welded strut frame was replaced by the cast strut support by VIN 52K 130X.

10
K Group 52-56 Frame Features Date Code/VIN Table of Running Changes
Frame Feature 52-56 Earliest Frame Date
Code/VIN Known
Latest Frame Date
Code/VIN Known
52 Neck casting First F3
Welded 52 Neck Casting 5/16 coarse thread coil bosses 3F
Welded 52 Neck Casting 3/8 fine thread coil bosses 4I
52A Neck Casting J3 4F
52A Neck Casting 5/16 Coarse Thread Coil Boss 4C
52A Neck Casting 3/8 Fine Thread Coil Boss 4H
55 Neck Casting D5 E5
Early No Stem Ridge 56 Neck Casting K5 A6
Later With Stem Ridge 56 Neck Casting D6 F6
Hollow Foot Peg Mounts First PRE E3
Solid Foot Peg Mounts Pre-E3 REST
Visible Casting # on Top Motor Mount No Date Code A6
No Visible Casting # on Top Motor Mount No Date Code H3
Threaded Rear Downtubes & Threaded Seat Post Bushing Sleeves First
Earliest K Seat Casting, Welded on Strut Supports First Pre-52K 130X
Early (Thinner) Seat Casting with Cast Fender Struts By VIN 52K 130X D5
Later (Thicker) Seat Casting with Cast Fender Struts A6 REST
Smashed underneath of backbone to accommodate XL Valve covers A6 REST
Note: Date Codes/VINs given are not necessary the earliest or latest but rather the earliest or latest codes known at this time. Legend: REST = All from the earliest Date Code forward First = From first bike model forward Copyright OSKRG 2014

13
57-66 XL, XLC, XLH & XLCH (Small Hole)
58 XLC & 58-66 XLCH will all have sleeved gas tank rear mounting hole, blue arrow. Many XLH frames will have an owner drilled hole to accommodate the small tank but it wont be sleeved. For 58-66 XLC & XLCH see slide 14.
1957 through 1966 XLH frames have 2 bosses for mounting the coil, green arrows and the Wedding Band strap for the oil tank bracket, yellow arrow. For XLH frames see slide #17.

14
58 XLC & 58-66 XLCH will all have sleeved gas tank rear mounting hole, blue arrow. Many XLH frames will have an owner drilled hole to accommodate the small tank but it wont be sleeved.
58-64 XLCH bare underside of seat casting, red arrow .
Voltage Regulator mounting boss used on 1965 XLCH only. Coil mounting boss used on 65 & 66 XLH. Earliest known appearance April 1964. Present through 1969. red arrow.
Lunch Box oil tank bracket , red arrow, used on 1966 models through 1969 with this seat casting design.
1959 & 60 XLCH only?? with large casting letter/numbers. Unclear if all 59 & 60 XLCHs have it and if XLHs have it as well as any other years. yellow arrow.
1966-1969 XLCHs have 2 voltage regulator mounting tabs. 1966 has no terminal strip boss below the regulator mounting tabs.
58 XLC & 58-66 XLCH (Small Hole)
1959 & on XLH and XLCH have threaded hole, yellow arrow, for speedometer cable bracket. 57 & 58 XL and XLCH necks do not have threaded hole.
Copyright OSK

rev.1 52-72 k & xl frame model year determination flow · pdf file3 hollow footpegs believe...

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