Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: 1970 Sportster Cylinders

  1. #1
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default 1970 Sportster Cylinders

    I'm starting the restoration of my 1970 CH. Years ago I stroked the motor and installed later-model cylinders and heads which I must now change back. I know that the heads were changed in 1970. I believe the cylinders were also changed in 1970 as well, but I'm really not sure what changed on the 1970 cylinders. I do know that the cylinders retained the 3.0" bore and earlier head bolt pattern.

    What I need to know is whether or not the external casting numbers were changed on the 1970 cylinders. I have 1957-1969 cylinders that I can use, but not if the casting numbers or actual casting features differ. Please advise.

    Thanks and HAPPY NEW YEAR!
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  2. #2
    Join Date
    Aug 2004
    Location
    Beautiful Northern New Mexico
    Posts
    2,458

    Default

    Bill, I think it was the base getting thicker.
    Robbie Knight Amca #2736

  3. #3
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default

    You're probably correct Robbie - in preparation for the larger diameter cylinders in 1972 - but still not sure if they changed the casting numbers from 16464-58 to 16464-70. Its likely that they did, as was their practice and if so these barrels are going to be difficult to find. Same case with the heads, which I'm almost certain have the updated casting numbers.
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  4. #4
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default

    Well, the good news is that I found heads on EBay; 1 NOS rear head (from Bill's custom cycles) and a used front head that needs very a small fin build-up. This is great news, as these were a 2-year only run. The cylinders were also a 2-year run and I'm guessing they'll be a bit more difficult to find if the casting numbers were indeed changed in 1970. If anyone has a real 1970 out there, I would appreciate knowing what the casting numbers are.
    Thanks...
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  5. #5
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default

    I received the heads and as I suspected, the rear head (From Bill's in Pennsylvania) is exactly as advertised; a real 1970 head. The casting number is A16683-57. However, I'm suspect of the front head which I received from another vendor. After removing the intake valve I noticed that it is an old XLR valve (1-15/16"). After further investigation I noticed that the intake guide has been cut down on top, obviously to accommodate high-lift cams. The intake valve port was full of oil which occasionally happened with the cut down guides, especially if the clearance was at the upper limit. Most troubling is the fact that the casting number is 16681-57 without the proceeding 'A'. I suspect that this may be the older casting with a ported intake track and larger valves being passed off as a 1970 head, but I'm not certain. Also, I would imagine that the 1970 front head would have the same 'A' code as the rear head to denote the 1970 change in the intake track and valve size, but I honestly don't remember.

    Before I protest the sale and hopefully send the head back for a refund, I need to know if the casting number is incorrect. Can anyone help out with this information?
    Last edited by Bill Pedalino; 01-04-2018 at 07:09 AM.
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  6. #6
    Join Date
    Jan 2018
    Posts
    19

    Default

    Just seen this post and thought I would toss some numbers in from Sportster Parts Catalog 1961 and later. Front cylinder and piston kit 16464-70, Rear cylinder kit 16465-70

  7. #7
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default

    Quote Originally Posted by TomL View Post
    Just seen this post and thought I would toss some numbers in from Sportster Parts Catalog 1961 and later. Front cylinder and piston kit 16464-70, Rear cylinder kit 16465-70
    Thanks Tom. I'm aware of the 1970 part numbers, but these numbers represent the cylinder/piston assemblies. I'm thinking that the cylinder did not change and the -70 part numbers reflect the change in the piston only, which was the fly-cut on the intake side which was needed to accommodate the larger intake valve. But I'm not positive.
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  8. #8
    Join Date
    Jan 2018
    Posts
    19

    Default

    Hello Bill, I have searched through my parts books and I can say for certain that In 1970 the Factory went to a 2 15/16" intake valve and it was used until the end of the Iron Heads with the big valve heads being numbered 16673-71F and 16674-71 respectfully. The 900cc motor was still in production through 71 but I am a little foggy on just when the 1000cc started, full year 72 or 1973 full year? I have a 68 "H" and the cylinders are cast 16581-57 Rear, 16561-57 Front, Heads are numbered 16683-57 Rear and 16681-57 Front. These are the small valve heads. Also from 54 to through 71 a 2 5/16" long cylinder base stud was used, starting in 72 until production ceased a 2 11/32" long stud set was used. Good luck with your build. TomL

  9. #9
    Join Date
    Mar 2005
    Location
    Huntington, New York - American Zone
    Posts
    777

    Default

    1972 was the switch-over to 1,000 CC's with change in head bolt positioning in 1973 and a final change in the head bolt pattern in 1974. I'm aware of the cylinder part numbers but am interested in the casting numbers on the left side of the cylinder bases. I now have the correct 1970 heads thanks to Bill's in Pa. and Dave Clemons. As I stated above, my belief is that the castings (and casting numbers) did not change in any way in 1970 and possibly in 1971, but the Part Numbers as stated the parts books did change due to the fly-cut valve pocket on the pistons. The valves were increased to 1-7/8" in 1970 and many of us increased them further to 1-15/16" using Harley XLR intake valves and porting the intake track. I have one of these heads from EBay that was passed off as a 1970 head (yes, I got taken). I worked at a Harley dealership during these years and well remember the transition to 1,000 CC's , but am a bit foggy as to the finer details of the cylinder transition. I do remember that the cylinder bases became thicker in 1972 along with the bore size increase to 3-3/16".
    Bill Pedalino
    Huntington, New York
    AMCA 6755

  10. #10
    Join Date
    Jan 2018
    Posts
    19

    Default

    Interesting, all my reference material on the valve size(intake only) say 1.825" 58 to 69 and 1.935" 70 to end of production. These numbers do not convert to a standard fraction but 1 7/8 and 1 15/16 are used. I do remember the confusion about 20 years after the 72-73 bastid head bolt-cylinder bolt pattern started showing up for rebuild at shops, mine included!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •