What do the letters on the lower end of fork tube stand for?

[sesamharold]

Hi to all XS650 experts!

At the moment we are discussing the meaning of the letters/characters that you will find at the lower end of your XS650 left and right fork tube - but no clue yet.

It seems that each side fork tube (esp. the "open" one with the seperate axle holder) shows two different letters, one near the front, the other one at the rear side. The following combinations have been found (but more may be in use):

"N" front - "U" rear
"F" front - "D" rear

Other letter combinations we found are W and N, O and A, O and H ....

Does anyone here know what those letters stand for. Is it a technical indicator, or from production (like release no.), or what? Do they stand as abbreviations for specific english words?

Please help.

Thank you in advance, with greetings from good old Germany!

 

[sesamharold]

I know, my english is not perfect, so here are two examples of what I would like to know more about:

 

[gggGary]

Just a note: one stud on the fork marked N U is stretched and needs to be replaced. If I think of it I'll look at my collection and see what I find.

 

[racerdave]

Good eye's Gary! The other stud on same leg is bent.

 

[gggGary]

I was being discrete and didn't mention that.

 

[sesamharold]

Yeah, eagle eye, that´s how the story started in the german XS650 internet community. Initially a guy asked for the best way to get those studs out from the fork tube. This problem has been solved already.

But through this thread and the above pictures we came across those "funny" letters, and still we have no idea about their meaning or system ....

 

[jayel]

just casting mold marks I would say

 

[Brian902]

I'm with jayel, just casting marks.

D F = Double Front
N U = Short for NOT YOURS

Ha Ha

Just joking of course.

The big think here is that the cap that slides over the studs and holds the axle tight is stepped. That is, if you put it on a flat surface and hold your finder on one side or the other there is one side that will sit flat and the opposite side will be 1/8" or 3mm off the surface.

The importance is that the thickest side goes to the front and is tightened to about 12-14 ft lbs first, then the thinner side or pinch side is tighten after to actual pinch the axle in place.

 

[xstra]

It seems that each side fork tube (esp. the "open" one with the seperate axle holder) shows two different letters, one near the front, the other one at the rear side. The following combinations have been found (but more may be in use):

"N" front - "U" rear
"F" front - "D" rear

Other letter combinations we found are W and N, O and A, O and H ....

These are different forks.. the DF clamp looks like a 34mm fork with one of the guard mount lugs removed, The NU is a later model 35mm fork. Do you have pictures of the others, WN,OA,OH?

Also, the DF studs are asymmetrically mounted.

I have 3 sets of XS650 and 1 set of SR500 forks-all with matching number/letter markings.

 

[gggGary]

I went out and looked around and found a possible answer?
The other leg also has marks, they may be either stamped or cast as part of the mold. I found at least one set with "matching marks" So my thought is the marks are to establish pairs, perhaps the pairs are clamped in a fixture before the axle hole is bored through both? Good info on the axle clamp tightening technique Brian "I didn't know that." I found the letters Sesamharold mentioned and the pair 1, D and others but what I was looking at were tubes off bikes so not many could be checked as "original pairs"

 

[5twins]

There is actually a direction arrow cast into the bottom of that axle clamp part. It should point forward .....

Some bikes use similar clamps for the handlebars and the front master cylinder bar mount. In the case of the master cylinder, the arrow should point up.

 

[Travis]

I just went and looked at two pairs of forks I have that are not mounted on bikes. I think one set is from an '81 and the other from an '80.

One set has the marks 6 L on one lower and 6 M on the other

The other set has the marks 7 Y and 7 Z

I have another set of 35mm forks but couldn't see any markings. And my SR500 has similar markings but I couldn't tell exactly what they were since the wheel is still on the bike. The forks on the SR500 look exactly like the 35mm XS650 forks.

 

[5twins]

Basically, they are the same, just different springs (softer) and preload spacers.

 

[sesamharold]

gggGary and Travis, very much appreciated are your comments. So far the only proposals that make sense to me.

So you guess that it is the same as with the upper and lower engine housing or with cylinder head and cylinderhead cover? Because those were also machined as matching pairs.