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Old 03-19-2012, 09:27 AM   #16
Donkey Hotey
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Something else changed on the front end. I had an '80. Was it the forks? 38mm to 43mm?
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Old 03-19-2012, 10:42 AM   #17
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That's it.

1980 forks.


1981-later forks.

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Old 03-19-2012, 11:36 AM   #18
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Haha... they're coming out of the woodwork now!

More about my rear wheel saga...

My original 1980 rear wheel was pretty much done for. Not only were the spokes rusty but I discovered a small crack in the rim. Apparently, it is not uncommon for these old rims to crack as I found out when searching for a replacement on ebay. Lots of “good” wheels were listed with cracked rims, jeeze.

It is also important to check the rim width when looking for a replacement. Keep in mind that the big bore bikes use a 2.50 x 18 rear rim. You would come up short with a YZ250 wheel as that one is only 2.15 x 18.

Eventually I found what was said to be an IT 490 wheel. Although the rim is silver, it is not the same as the one on my IT490. The IT490 has squarer edges and is supposed to be stronger and heavier than the YZ rim. This one has a silver 18 in rim of the type a YZ would have.

Perhaps it is a later, post gold rim, YZ490 model, I'm not sure. One thing in clear, it uses a “standard” type hub, not the z-spoke design.

In any case, it uses the larger diameter axle (like the 1981 465 and 490's as others have mentioned). Another difference is the number of wheel bearings used. The 1980 hub has a single cartridge wheel bearing in each side. The 1981 YZ465 and 490 hubs use two bearings on each side, very beefy!

The good news is that the wheel was in decent condition with good spokes. It also came with a brake plate and the axle assembly, including all the chain puller do dads.

Of course, using the later model hub with large axle in my 1980 swing arm took some doing. Several steps were required,

1) Mill open the axle slot in the swing arm. This was an awkward process as my mill is too small for this job. In the end, I simply bolted the arm to the table the best I could and took very light cuts until I was within 5 thou of the needed dimension. I then used a file to get the finished dimension. I only cut the bottom side of the axle slot. I used the “flats” of YZ490 chain adjuster spacers as a gauge to check my fit. The fit was kept tight across the slot to ensure the bottom side would remain parallel to the factory machined top side.

2) It turns out the 490 swing arm is thicker than the yz465 at the axle mounts. This can be seen in the different in the chain adjust spacers and the internal width of the adjusters themselves. The fix was to mill the width of the 490 spacers to match the 465 spacers. As for the adjusters, I simply squeezed them down in a vice to the necessary size. I left the end portion of the adjuster outside the vice jaws. This allowed the adjuster side plates to follow the threaded end tab to give a neater appearance.

3) Finally, I cut a new axle spacer for the left side. The right side needs no spacer. The 490 brake plate is different than the 465 plate (’80 or ’81) and the "spacer" is cast as part of the plate. In cutting the left side spacer I took care to keep the sprocket spaced off the arm exactly the same as on the 465 hub. I was willing to re-center the rim through spoke adjustment if needed. Fortunately, the wheel was well centered without having to do this.

With all of this said and done, plus some new bearings, I had the 490 wheel mounted and ready to go.

Here are the photos to go with the description.

First the ugly 1980 wheel. Note the studs in the hub to mount the sprocket. The '81 and 490 hubs use bolts that thread into the hub.


Next is a ugly 1981 wheel. These have the big axle and double bearings. I will re-lace with new spokes and rim in future.



And a nice clean YZ490 wheel test mounted in the 1980 arm



Milling the swingarm with very light cuts, final dimensioning by hand...


New All Balls rear wheel bearings. Note, bearing have seals on both sides, I like that!


Here are the axle adjuster spacers, left side is the 490 (too long), right is the 465.



Milling the 490 spacer...


Now they match!



Squeezed down 490 chain adjuster



More to come... but first,

Marty Moates at the Carlsbad USGP

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Old 03-19-2012, 02:21 PM   #19
riceless950
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Lovin' this thread! I just started a '78 YZ400 project so as you might image, this is very interesting and helpful to me. Also diggin' the, never before seen (by me) race photos. Subscribed.
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Old 03-19-2012, 02:27 PM   #20
Sniper X
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Old 03-19-2012, 03:37 PM   #21
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Shiny and pretty. But it's a garage Queen. Not what they're made for. I still ride and even race my YZ465 occasionally. And do pretty well too. It might be old but it was the cream of the class. Others made more power,some turned better but none had the package balance.
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Old 03-19-2012, 03:48 PM   #22
Donkey Hotey
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Quote:
Originally Posted by anotherguy View Post
Shiny and pretty. But it's a garage Queen.
Maybe so but, that ain't no YZ. Dead giveaways are the aluminum tank, the straight bars on the swingarm, the lettering on the right side engine case, etc. That's a real OW.
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Old 03-19-2012, 06:58 PM   #23
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yes it is. And they were made to ride as well.
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Old 03-19-2012, 07:11 PM   #24
Afry
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Great thread! Sure brings back some great memory's.

I used to ride 490's on short hard pan tracks in Nocal - Baylands, Santa Clara PAL etc and found out that the bike flat hooked up by lowering the compression. I stacked two copper head gaskets on top and let her rip.
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Old 03-20-2012, 12:14 PM   #25
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Sniper X: Nice photos... yes that is Rick Burgetts OW41

Those photos reminded me to pass along these two books that I have been really enjoying. You will find plenty of good information on the OW Yamahas in these. Both include lots of great photographs and comments, even some from the riders who rode these machines. I found it very interesting to compare various aspects of our production bikes with what was done on the factory rides.



VMX magazine is another great resource. They have run several features on the Yamaha factory racers as well as articles covering restoration of the production bikes. Many of the back issues are still available.

Then there are the period magazine reviews. I found some of these in the Yahoo YZ490 group and others in the IT Enduro Club ( http://www.yamahait.com.au/forum/ ) . Even more YZ tests can be found here ( http://www.simnet.is/skulitho/YZ_stuff/ )



Now, turning back (yuk yuk ) to the rear wheel discussion...

I wanted to point out a difference between the OEM Yamaha spokes and the Buchanan stainless spokes. The OEM spokes are butted (thicker diameter) at the end. The Buchanan stainless spokes are straight guage.

I am wondering if someone can comment on the general durability of the stainless spokes. Are they more or less reliable than the OEM's. They certainly look great, how do they hold up?

These photos should show the difference in spokes and the differences in the brake plate/spacer setup.

Here is the yz490 with butted spokes at the bend. There is no space between the plate and the swing arm, only the dust cover for the brake plate bushing.




Now, here is the '81 yz465 wheel with Buchanan stainless spokes. You can see there is no change in diameter at the bends. On the '81, the spacer is welded to the chain adjuster (I've rotated the brake plate to get a better view).

BTW, the 490 has the nice aluminum brake arm. Much nicer than this ugly stamped steel thing I found on my 465.




Finally, here are a couple of tools that have come in handy through the years.
On the left is a cheap tire bead breaker. I guess I wouldn't want to bring it on the ISDT but does make tire changing around the garage much easier. I can do motorcycle and car tires with this and a big set of spoons I have.

On the right is a wheel truing stand my father made in around 1970. As a kid, I remember him cutting threads for it on the lathe. Then he had me hold a piece or 2 in place while he laid down some tack welds.

And before anyone asks, this is not my wifes living room....oh, no,no,no.
This is the finished upstairs of my moto barn.


So how about it "anotherguy" you like those "fancy dan" stainless spokes? Breaking any?

And for Riceless950...

#23 Marty Moates on his 1980 LOP YZ465 showing em how its done!


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Old 03-21-2012, 12:05 PM   #26
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OK... with the 490 rear wheel worked out I was able to install the swing arm for the final time.

The next step for me is to work out a 43mm fork swap. I also picked up a used, side port, DG YZ- 490 pipe that I will adapt to the 465. The original pipe was patched and welded numerous times so I was happy to get this pipe at a good price. Comparing the pipes, I found the 490 one to be very similar to the 465, the main difference being in the length of the stinger and how it attaches to the silencer.

This photo below shows the bike with modified swing arm,YZ490 wheel, and a set of 1983 43mm IT-490 forks (more about that later). A motor was fitted temporarily to help work out the mounts for the DG pipe and new silencer.

You may also notice that I have mounted the aluminum rear brake stay from a yz490 in place of the steel 465 arm.
It appears the 490 arm is a bit too long as the plate is rotated in clockwise direction too far. This compromises the positioning of the brake actuating arm. My plan is to cut and reweld the stay arm at the rear attachment point. It will also be necessary to fit a spacer at the frame side as the arm eyelet not as wide as the frame bracket it bolts into.



Chain Guides:

Old plastic chain guides can get brittle and break thereby jamming the drive train. To avoid these issues, I went ahead and replaced all the guides and chain rollers. Fortunately, all the chain guide plastic is still available from Yamaha as well as other sources.

The rear guide itself is made from aluminum and quite light. In addition to plastic, mine required cleaning and some new screws. The inside of the guide bracket is left bare aluminum. The outside part is repainted using a "hammered" finish that is durable and effective in hiding minor imperfections.




Next up will be fork swap details. But first,

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Old 03-22-2012, 08:37 PM   #27
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Quote:
Originally Posted by FJ_Kevin View Post
how about it "anotherguy" you like those "fancy dan" stainless spokes? Breaking any?
Nope. Not yet. But they're just 11 years old.
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Old 03-23-2012, 10:55 AM   #28
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The brake stay arm is supposed to form a parrallelogram with the swingarm so bumps don't affect the braking action.

I attended the premiere of the USGP movie in San Diego and bought a Marty poster... what a great night!

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Old 03-23-2012, 04:55 PM   #29
anotherguy
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I went out to the garage and measured the spokes while Dog was eating. The front spoke is .143" and rear measures .157". Butting spokes is a strengthening practice for weight savings. Doesn't make that spindly thing as strong as a straight gage spoke except in the loaded area by the hub.

A double butted spoke (both ends thicker) has more elasticity than a straight gage and will tranfer loads to adjacent spokes under heavy loads to avoid breaking. But that's more for bicycle wheels where they're treading thin ice on strength. Like I said those spokes have some mileage on them and............well I'm no lightweight so they've been subjected to considerable punishment.

My CRF 450R has straight gage stainless spokes as well and they are 8 years old and subjected to the same punishment. When you carry my bulk saving weight by the gram is simply nonsense.
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Old 03-23-2012, 07:19 PM   #30
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Originally Posted by lemieuxmc View Post
The brake stay arm is supposed to form a parrallelogram with the swingarm so bumps don't affect the braking action.

I attended the premiere of the USGP movie in San Diego and bought a Marty poster... what a great night!
lemieuxmc - Thanks for the reminder about this. I measured the 490 brake stay to be about 3/4" longer than the 465. Doesn't sound like much but it causes some interference back there. I am going to try and shorten it tomorrow.

I would have loved to attend that event. I did pick up the DVD this winter and really enjoyed it. Also the extra clips of the Moates bike being prepped at Vintage Iron. The race itself was great!

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