1970 Sportster Cylinders

[billpedalino]

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!

[Rubone]

Bill, I think it was the base getting thicker.

[billpedalino]

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.

[billpedalino]

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...

[billpedalino]

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?

[TomL]

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

[billpedalino]

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.

[TomL]

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

[billpedalino]

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".

[TomL]

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!

[billpedalino]

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!

You may very well be correct Tom - I'm going from memory and it was a long time ago. I do know for certain that we go-fast guys did change these larger intake valves to the XLR valves (which were a real 1-15/16") because of the tulip shape and how this shape aided airflow into the intake the track, which we invariably ported. The 1-3/4" XLR exhaust valves were also installed, as they were shaped as well.

Yes, that 1973 cylinder/head combination was a winner! I com pained about finding my 1970 heads - but the guys doing 1 1973 have a much tougher time!