Difference between 72-73 and 74-76 fork tubes

[f-lix]

Hey guys.
I need a new pair of upper front fork legs for my bike. Bought them of a dude who didn´t know the year of them. They are 34mm wide So they got to be somewhere between -72 to -76. At mikesxs they have have two different sets. -72 to -73 and -74 to -76.
Can anyone tell me the difference? Can I measure them somewhere to tell? Been trying to email mikes, but haven´t got any answer. Need to know so I can get me front end up and running!

Thanks! Felix from Sweden

 

[raptorhertz]

looking for same information too.I read that pre 1977-71 has same 34mm Inner tubes.

 

[f-lix]

Did get the answer from mikesxs. the 72-73 are 22 3/4" and the 74-76 are 22 7/8".

 

[da evil one]

one word: micrometer. i gotta buy one too. that would have answered your question and came in handy in the future as well.

 

[pumps]

Harbor freight. Bought this caliper with a coupon I think for $9.99. Need a socket for a big nut but don't know the size? Measure it! Does inches or mm. Comes with an extra battery. Look for a Harbor freight coupon in the back of your favorite motorcycle mag.
http://www.harborfreight.com/4-inch-digital-caliper-47256.html

 

[jayel]

one word: micrometer. i gotta buy one too. that would have answered your question and came in handy in the future as well.

the difference was in the lenght

(Did get the answer from mikesxs. the 72-73 are 22 3/4" and the 74-76 are 22 7/8")

that would be one big caliper set

 

[da evil one]

ahh....yeah. sleep typing again. i dont think that length difference wouldve mattered as long as diam. was good.

 

[XSLeo]

The 70 fork used an external spring, as well as tube had the damper made as part of the tube.
In 71 they put the spring inside the tube. The tube still had the damper as part of the tube.
In 72 they changed the tube to a straight tube and put the damper inside with the spring. They also changed the way the axle clamps to the bottom of the fork. the 70-71 had a round part one the bottom. One side was split and had a clamp bolt. In 72 the bottom looked like an extension of the fork lower. With a hole in one side and a removable cap to clamp the axle on the other.
The 70-71 tubes have a screw on top nut that holds the tube into the lower part of the fork. In 72 they just had the slip on dust cover.
So, how do your fork lowers look? Threaded at the top or just smooth?
Pics would help.

 

[scobman]

The width of the tree is wider '73-76
The width of the tree is not as wide '71-'72
RARE '70 forks with outer spring for sale. Thats rare.
http://www.ioffer.com/i/yamaha-xs1-1970-front-forks-motorcycle-rare-xs2-xs650-495658874