I Noticed Something Very Interesting and Would Like Input

So, I was cleaning up the bike the other day when it was too drizzly to ride, and I noticed something.

Then I went and looked at my '81, and the '82 650. And it seems to be common.

The shiny parts on the wheel rims, the part where they've been machined back to shiny metal (not looking at the spokes) are different front-to-rear.

The front rims are more finely machined than the rear. It's as though they got an extra pass or two on the rotary mill or whatever they cut them with.

The machining is "tighter" to the point of being almost nonexistent on the front rims (just the rim part not necessarily the spokes) whereas it's much less finished on the rears. Noticeable, anyway.

I'm wondering if Yamaha, carefully observing their customer's habits, decided everybody's rear wheel got dirtier (and often stayed that way) than the front so they didn't "cut" them as shiny to begin with?

Check yours out and vote. I thought maybe it was just a "vendor/supplier/subcontractor" variation until I observed it to carry across all of my XJs from model years '81, '82 and '83.

Whatcha think?

 

You SURE you wanna know what I think!?!?!? LOL

Dave F

 

I have already polished mine smooth on the XJ , but if I remember they were both the same before I did it. I looked on my other bikes and the cut looks the same on them.

 

Re: I Noticed Something Very Interesting and Would Like Inpu

I take a peek at mine tomorrow after work. Now I'm curious too.

 

On my '83 especially, there are virtually no "cutting marks" on the front rim where it was machined. It's as smooth as an engine case. On the rear, they're very fine in the same area, but visible.

On the '81, there are very faint machining grooves front, more distinct rear.

But then again the 550 Secas are unique in that they have straight-spoked wheels.

On my "swirly wheels" 650, the difference is less noticeable but still there under close inspection.

Maybe I should narrow this to 400/500/550/600 Secas and RD/SR or other Yammies with the straight-spoked wheels?

Maybe it is a Tier 1 or Tier 2 supplier thing?

And one vote does not make for reliable data, Dave. No stuffing the ballot box. I'm just curious.

This is like the black vs. silver sprockets on the 550 Seca thing. According to Yamaha, the '82 and '83 550 Secas were supposed to have black rear sprockets. The official factory spare parts for all three years' 550 Seca were black. I have an '81 (46T) on my garage wall and a later one (45T) on my bike and they're black.

Yet every original 550 Seca I've ever seen, without exception, every pic, anywhere clearly shows that they came out of the factory with silver rear sprockets. I have YET to find anyone that has seen an original black rear sprocket on a 550 Seca. They came with silver ones, but the spares were black. Factory parts labels on them.

You wanna get hinky? Start comparing brake components, caliper and M/C that are the "same" very closely. Same bike, different years, etc.

It gets interesting.

 

The difference could be just a matter of differences in the sharpness of the tooling when the rims were machined. If the run was set up so the fronts were made at the beginning of the shift, and the rears run after all the fronts were made, the tooling marks would be more distinct on the rears than on the front. When my dad worked in the tool and die shop at Freightligner, SOP was to try and run the tooling for a full shift before resharpening, or two shifts if the material being worked allowed.

 

i have 4,672 stitches in me seat, does that sound right

 

Definitely 2 more than me.

 

As being a machinist, I agree with k-moe

 

Do you still have clear lacquer on your rims Fitz?

 

on my '82 XJ750J Maxim, my rears are butt smooth vs the fronts which are rough...go figure.....

The backs must have been cut on Monday morning & the fronts cut on Friday afternoon right before happy hour....

Those Japs....running off to drink their saki & singing their karaoke.......

 

Yamaha never lacquered the rims as far as I know. I've owned five cast-wheel Yammies over the years including my current three, and none of the rims are/were lacquered.

And Yamaha didn't actually manufacture the wheels, they were made by a supplier or suppliers, which explains the differences. Especially since we now have an example of finer machining on a rear than on a front.

The only real conclusion that can be drawn at this point is that it wasn't intentionally specified as I originally theorized.

 

Re: I Noticed Something Very Interesting and Would Like Inpu

I used 600 grit emery paper on the rear while it was on center stand rotating.
Can still see very light tool marks, front was done the same, but not rotating (duh), can see very light tool marks also.

I'm with kmoe on this one.

 

550, 650, & 750......each have their own issues with regards to tool marks.....bad quality control by supplier....

 

I think that it's not so much a matter of quality control as a matter of the standard that the parts were meant to be finished to. If Yamaha had specified that finished wheels were to have no visible tooling marks then the wheels would have been ground and polished after the machining was done, but that would have added to the cost of the wheels (and the price of the bikes).

Ten cents saved in production costs per-part adds up to real money over the total production run.

 

Exactly. Although apparently some wheels were made "better than spec" it was probably simply a matter of the production run/tool wear variations as you described above.

 

Well, when the wheels are rotating at 70 mph, I don't think anyone
will notice the imperfections.

 

I don't have any stitches in my seat..........my rear is butt-smooth, too. Getting older, but still smooth...........LOL

Dave

 

As being a machinist, I agree with k-moe