OSKRG Research/Restoration Bulletin #2C 66-71Tillotson Carburetors

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Lawrence Johns
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1 1 OSKRG Research/Restoration Bulletin #2C 66-71Tillotson Carburetors VS.1 This research and restoration bulletin 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: graino@comcast.net & sklange@comcast.net

2 2 Forward As the opening statement on page 1 states This research and restoration bulletin 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. This work is by no means definitive. A realistic expectation of this work would be that there are going to be errors but at least it is a place to start the conversation from. Consider this bulletin to be a living thesis, as empirical evidence presents itself this document will be modified to more accurately reflect what was original equipment on the Sportsters from 1966 through It addresses the Tillotson series of carburetors. There are a number of models and years that remain a little unclear like which HD carb was used on the 71 models and were any of the HD2 series carbs ever stock on any of the Sportsters. If you have a bike that you are confident has its original carb on it we would love to hear from you. Within the document we have a score card of sorts to track what carb people have on their original bikes, this score card can serve as an important validation tool. Hopefully over time we can mold this document into a valuable tool to help enthusiast in their restoration efforts.

3 3 Table of Contents Section 3, Tillotson Carburetors: Page 50 Tillotson Carburetor Model, Tillotson Carburetor Part Number, Jet Diameter/Number & Comments Tillotson Carburetor Significant Part Number Changes from Parts Book to Parts Book What Is Actually On Your Bike-Please Let Us Know XLH & Gas Tank Fuel Valve & Outlet XLH & Air Cleaner Back Plate, Cover & Filter Tillotson Choke Assembly 1966 Only XLH & Tillotson Choke Assembly Tillotson Tickler & Main Jet Size vs. Needle Turns Out Comments about the Tillotson Series of Carburetors by Bob Evans Comments about the Tillotson Series of Carburetors by Dr. Dick Additional Comments about the Tillotson Series of Carburetors by Dave C.

4 Tillotson Carburetor Model Section Tillotson Carburetors Green Indicates Some Degree of Confidence Carb was Original Equipment-Yellow indicates Uncertainty (R12) Part Number Tillotson Factory Original Drawing Dates HD-1A Sept HD-1A Tillotson Factory Comments: The HD label was created specifically because of the Harley motorcycle, so that would be the earliest year you would see a Tillotson on a Harley. It could have been as much 1 or 2 years later, depending on how much testing they did. The last modification to the drawings was in August Comments by Others: XLH-. 1 year only choke lever. Believe that the HD-1A & HD-1B were used with staggered duals. (Dave C.) HD-1B A Jan HD-1B Tillotson Factory Comments: The last modification was in October Comments by Others: Service bulletin # 547, dated Oct.24 / 66 all 's produced after Aug.10 / 66 (from VIN ) will have the new inlet valve; new carbs identified as HD-1B. The upgrade (repair) kit for HD-1A use ordering # (Lloyd G.) XLH-. Believe that the HD-1A & HD-1B were used with staggered duals. (Dave C.) HD-1BC B Jan May be some late 67s with the HD-1BC HD-1BC Run Change to HD-1C Tillotson Factory Comments: I think this was an intermediary bridge between the B and the C. I wouldn't be surprised if it was some kind of minor midyear running change that eventually morphed into the C. Comments by Others: Service bulletin # 571 dated May 21 / 68 says late ' 68 Sportsters will now have the new B Tillotson carb with new checkball in the plastic pump body to stop air bleedback. The new carbs are stamped HD-1BC and HD-1C. To order just the new plastic plate with the check ball the order # is A. HD-1C C Nov HD-1BC Run Change to HD-1C HD-1C HD-1C Run Change to HD-1CD Tillotson Factory Comments: Last modification in Comments by Others: XLH-. HD-1C was 68 at least in California which used the "Bronson" pipes in 68 & 69, HD-1D running change from HD-1C in (Dave C.) HD-1CD OCT HD-1CD Run Change to HD-1D Tillotson Factory Comments: The dates were scratched off but I could read them as October 1967.The drawings specifically note that it is the same as the HD-1D so again I think it was some kind of transition numbering. HD-1D March 1970 HD-1CD Run Change to HD-1D Tillotson Factory Comments: From what people remember, the 1's were all in succession so my guess is that the 1A was used sometime between 1964 and 1966, then it went to a B and C until 1969 then the D took over as the final model. I suspect the modifications to the A-C were fixes that were carried back for replacement purposes. I think you can assume that Harley stopped ordering the older models for NEW production on or very near the date of the drawings for the new model. Comments by Others: HD-1D running change from HD-1C in Believe this may have been a running change with the 1970 switch from the more costly "Bronson" exhaust to the Bagpipe, which had even smaller diameter exhaust pipes than their predecessors. (Dave C.) HD-1D

HD-2C Comments by Others: HD-1D was 1970 and 71 believe Harley used HD-2C's or HD-2D s or whatever was left over from Big Twins fitted with Tillotsons from 67 to 70. (Dave C.) HD-2D Nov.

5 HD-2C Comments by Others: HD-1D was 1970 and 71 believe Harley used HD-2C's or HD-2D s or whatever was left over from Big Twins fitted with Tillotsons from 67 to 70. (Dave C.) HD-2D Nov Comments by Others: HD-1D was 1970 and 71 believe Harley used HD-2C's or HD-2D s or whatever was left over from Big Twins fitted with Tillotsons from 67 to 70. (Dave C.) General Comments: Some of this is verified by the sundial date code on some Tillotson bodies. The model change with the exhaust change is a fairly logical story. (Dave C.) HD-2C? or HD-2D? HD-2C? or HD-2D?

6 Tillotson Carburetors Tillotson Carburetor Significant Part Number Changes from Parts Book to Parts Book vs.1 Note: A column Part Number Color Change Indicates a Part Number Change. Text in Red Indicates What the part is Supposed to Fit has Changed. Parts Book Year Carburetor Complete Part Number Possible Tillotson Carburetor Model Inlet Needle, Seat & Gasket Inlet Lever, Needle, Seat & Gasket Carburetor Main Jet Bracket Throttle Cable Throttle Shaft & Lever Wire Block, Throttle Lever Retainer Clip, Choke Wire Block Wire Block, Choke Lever Choke Shaft & Lever Lever, Inlet Valve Welch Plug, Check Ball 1967 PB XLH & A 67 XLH & HD 1A XLH & HD 1B XLH STD to 66 XL, XLH & XLH & XLH & XLH & XLH & XLH & XLH & XLH & XLH & XLH & XLH & 1971 PB C 66 to 71 XLH &???????? to 71 XLH & STD to 71 XLH & to 71 XLH & to 71 XLH & to 71 XLH & to 71 XLH & to 71 XLH & to 71 XLH & to Early 70 XLH & Parts Book Year Stud, Carburetor Adaptor-2 Stud, Carburetor Adaptor-1 & 5/8 Insulating Block, Carburetor Mounting Insulating Block, Carburetor Mounting Friction Spring, Choke Shaft 1967 PB to 67 XLH & 1971 PB to to 71 XLH & to to 71 XLH, 66 & 70 to to 71 XLH & Supplement to 71 XLH & (Replaces )

7 6 What Is Actually On Your Bike-Please Let Us Know Tillotson Model XLH XLH XLH XLH XLH XLH HD1A HD1B 1 HD1C 1 HD1D HD2C HD2D OTHER

8 7 Tillotson Restored by Dave C.

8 XLH & Gas Tank Fuel Valve & Outlet PN 62125-55 Fuel Valve Assembly is listed as the valve

The 71 Parts Book list PN 62125-55B for the 57 through 71 XL & XLH as well as the 65 through

9 8 XLH & Gas Tank Fuel Valve & Outlet PN Fuel Valve Assembly is listed as the valve through the 67 Parts Book for 57 through 67 XL & XLH. It is listed for the from 65 through 67. The 71 Parts Book list PN B for the 57 through 71 XL & XLH as well as the 65 through 71. At this time I am unaware of a PN A PN PN A if it Exists? PN B

9 66-71 XLH & Air Cleaner Back Plate, Cover & Filter Note: Above Part 36 has a 29205-69 Part

10 XLH & Air Cleaner Back Plate, Cover & Filter Note: Above Part 36 has a Part Number, may have been used on 69-71? Backing Plate Air Filter Element Air Cleaner Cover Air Cleaner Trim

11 10 Tillotson Choke Assembly 1966 Only XLH &

12 11 Tillotson Choke Assembly Choke Assembly

13 12 Tillotson Tickler & Main Jet Size vs. Needle Turns Out

14 13 Comments about the Tillotson Series of Carburetors by Bob Evans Sundial; Best I'll conclude is that it is a 'cast date code' since it is cast in. It did not show up until later in production, (1968 I think?). And there are later HD1C's and D's that don't have it, so? WTF? But you re A, B, C & D's seem correct. Off the top of my head I view it this way; HD1A, 1966 only and no 'forked fuel inlet lever' as shipped. This became a running change probably late in 1966 production when the hard starting complaints received attention. The original lever depended upon gravity for the fuel inlet needle to drop off its seat, allowing fuel to enter the diaphragm area. If the cycle was not started often enough, the fuel would begin to dry out slightly, effectively 'gluing' the needle to the seat and no fuel could enter the carb. (My all original 1966 had this early inlet needle and lever along with Zach R s personal notes on the cycle stating why he finally gave up riding it with only 1,300 miles on the clock. He constantly complained in his notes of what a bastard it was to start. After I won the cycle at auction I brought it home and knew what to look at first as I had previously read the HD service bulletin on this. Sure enough, it had the original parts. I changed them out and the cycle started on the fifth kick! Also as you mention, 1966 was a one year only choke lever arrived with the HD1B, presumably with the changed choke arrangement and the forked inlet lever which allowed manual priming of the carb through the tiny air hole in the bottom of the diaphragm cover. By physically sticking a toothpick or straightened out paperclip through the hole you lifted the fuel needle off its seat allowing fuel to enter and freeing up the needle from the seat. The aftermarket offered 'Tillotson ticklers' which screwed to the bottom of the diaphragm cover to make this task easier may have 'B's or 'C's on them. There are no changes that I am aware of except for the possibility of a different main jet. As we all know the idle and midrange are adjustable so no likelihood of a change there may have 'C's or 'D's on them, otherwise same as and 1971 only ever had HD1D's on them, every stock cycle that I've ever seen. And 'HD5' carbs were KR, XLR and iron XR carbs that had no accelerator pump, a plain stamped steel diaphragm cover and adjustable main jet rather than fixed. Andrew's Products offered their 'Super 45' variation of the Tillotson around It was usually stamped either HD137 or HD138, had no high speed venturi, (aka bomb site), and was bored out to 45 mm. I had one and it worked great. There may have been main jet changes depending on exhaust system options. Finally, I will repeat what I read in a cycle magazine article about Tillotsons some 45 years ago; Though both the HD1's and HD2's may appear identical, there is one major difference that has driven guys crazy when trying to get a HD2 to idle properly on their Sportster. The tiny idle bleed holes are larger in the HD2 causing an always rich mixture on a smaller engine. Regards, -Bob-

14 Comments about the Tillotson Series of Carburetors by Dr.

Dick wrote: Here s what I think. I don t know for sure.

block to arm attachment, riveted instead (some with friction

15 14 Comments about the Tillotson Series of Carburetors by Dr. Dick & Some Pictures Also Comments by Dave C. Dr. Dick wrote: Here s what I think. I don t know for sure. 66 HD1A no forked inlet needle, no cotter pin at throttle block to arm attachment, riveted instead (some with friction spring some without). No check ball in plastic cover. 67 HD1B was opposite of the above. 68 HD1C difference in idle porting positions and maybe a difference in economizer jet size. 69 I don t know. 70 and 71 HD1D.

15 Insulator Blocks and Stud info: 66 blocks had no drill point; it used the Linkert throttle bracket. 67 the point was added, but there was no PN change.

t=1567534 Post 36 Dave C wrote: Jerry, Kudos to Joe on the K Model site post regarding the one year only (HD1A) riveted throttle wire mount and no check ball in the diaphragm cover (check it out).

16 15 Insulator Blocks and Stud info: 66 blocks had no drill point; it used the Linkert throttle bracket. 67 the point was added, but there was no PN change. In mid 67 the lower stud got lightened for plug wire router. Feast your eyes on this. More of my silly tilly ramblings Post 36 Dave C wrote: Jerry, Kudos to Joe on the K Model site post regarding the one year only (HD1A) riveted throttle wire mount and no check ball in the diaphragm cover (check it out). That needs to be added to your write-up. We learn something new every day. I will make these changes to my restored 1A for my 66CH restoration. About the only adder to the Tillotson section is the idle adjustment screw (the big one on top) was tapered in 66 and incorporated a step stop on the HD1B, possibly late HD1A's. The service bulletin that Scott posted some time ago had this description with a drawing. The change was made to prevent over tightening of the screw and distortion of the idle fuel metering hole. Presently I am of the opinion that the 68's had HD1C's due to the mix of exhausts that year. Other than the HD1A idle needle and 1C's on the 68, I believe we are good to go (if that ever happens). Dave C

OSKRG Research/Restoration Bulletin #7 Sportsters Kick Starter Parts This research and restoration bulletin was created with input and

OSKRG Research/Restoration Bulletin #7 Sportsters 57-79 Kick Starter Parts This research and restoration bulletin was created with input and assistance from members of the OSKRG. The report consolidates