Barrel spec help needed please

C

crazy

Registered User
My 1973 sportster barrels have 682-71 and 6684-71 stamped on the casting!
Could any of you clever guys tell me any specifications on them as I need to get them checked for wear!

Much obliged

Crazy 🤪
Fln742j@gmail.com
 
If you do Facebook, the best online resource by far is a page called The Ironhead Sportster Garage. What they don't know on there isn't worth knowing.

What I do know is that the 1973 model year was the first year for "proper" 1000 cc Sportsters, 1971/2 being a crossover year when they effectively utilised bored-out 900 barrels. That explains the "-71" bit as this denotes the first year in which that part was made, earlier than that would have had a "-57" number.

In those days the barrels would be cast, and then left to age-harden so they wouldn't have been fitted till late 1972 when the 1973 model year started.

Sorry if this seems clear as mud but it's how H-D do things!
 
I appreciate the replies, I have found the below which helps!

Hopefully if someone else searches barrel spec dimensions they may come across this post!

Regards
crazy

Sportster late 1973-1985
front
nominal bore: 3-3/16 ”
inner Ø: 80.85 mm

Sportster late 1973-1985
rear
nominal bore: 3-3/16 ”
inner Ø: 80.85 mm

Sportster 1972-early 1973
front
nominal bore: 3-3/16 ”
inner Ø: 81.00 mm

Sportster 1972-early 1973
rear
nominal bore: 3-3/16 ”
inner Ø: 81.00 mm
 
That's right. It all hinges on how much you can overbore them; 72 to early 73 only go out to 30 thou. This is because they're already bored out 900's as I mentioned above. By the way, they are not interchangeable without changing the heads as well, stud patterns are different.
 
kevscrivener said:
If you do Facebook, the best online resource by far is a page called The Ironhead Sportster Garage. What they don't know on there isn't worth knowing.

What I do know is that the 1973 model year was the first year for "proper" 1000 cc Sportsters, 1971/2 being a crossover year when they effectively utilised bored-out 900 barrels. That explains the "-71" bit as this denotes the first year in which that part was made, earlier than that would have had a "-57" number.

In those days the barrels would be cast, and then left to age-harden so they wouldn't have been fitted till late 1972 when the 1973 model year started.

Sorry if this seems clear as mud but it's how H-D do things!
Click to expand...
When I was at Lucas as an apprentice in '69, there was an area of open roofing that was covered in castings.
They called it Weathering and it basically allowed the years long temperatures to take the stresses out of the castings.
 
Engine Displacement Chart Order by Bore and Stroke.jpg
 
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