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Old 03-23-2012, 07:28 PM   #31
FJ_Kevin OP
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Quote:
Originally Posted by anotherguy View Post
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.
Thanks for the measurements and feedback. Those Buchanan guys have been around a long time. I remember them in the '70's. There was a nice article about them in Motorcycle Classics, it was great to see they are still around.

I agree with you. I am sure those spokes can take much more of a beating than I can these days...

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Old 03-23-2012, 09:00 PM   #32
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43MM Fork Upgrade

Alright, I will warn you now I may have gone a bit overboard here but maybe someone else will find this info useful

As others have mentioned, the 1980 YZ465 used a 38mm fork with double leading shoe front brake (the 1980 YZ250 used a single leading shoe brake - correction per Greg below, thanks!). For 1981, Yamaha upgraded the 465 with a 43mm fork and continued with double leading shoe front brake. The 43mm fork and DLS was also used on the YZ/IT490's and 250's until 1984. In 1985, the DLS brake was replaced by disc.

There are a few things to be aware of when considering the 43mm fork upgrade. First, ahrma post vintage rules require drum brakes. So for me that meant a pre-1985 fork. Second, there are two styles for DLS brake plates. The difference is in the location of the anchor tab. The 1981 brake plate has the anchor in the 1 o'clock position which the '82-'84 plates have it in the 3: o'clock position.

This means the '82-'84 brake plate will not fit the '81 43mm fork slider and vice versa.

If you wish to stay with a 38mm fork on your 1980 YZ250, you can upgrade to the DLB but it must be the 1980-81 YZ plate.

The following pictures compare the front and bake of single and double -leading shoe brake plates.
Left is the single leading shoe, anchor at 1 o'clock. Right is 82-84 DLS plate with 3 o'clock anchor.




The next photo shows the 1981 DLS brake with 1 o'clock anchor. You can also see the corresponding difference in the brake tab location on these two 43mm fork sliders ('81 yz465 slider on left, 83 IT490 slider on right).



A couple of more things,
- The brake levers on the '81 DLS plate are steel, the later levers are aluminum
- The DLS brake shoes are different than the SLS shoes.
- The brake springs are the same.
- Be sure to clean and lube all the pivot points, it makes a big difference!
- Adjusting the DLS takes some patience to get both shoes to hit the drum at the same time.

Now, while it is true that the fork tube diameter was the same across many years of the 490, the fork internals can vary significantly from one model year to another.

Examination of part numbers show differences in springs and damper rods through the years as well as the appeance of a new device called a compression damping blow off valve.

The compression blow off valve was introduced on the ’83 YZ/IT 490. As I had a set of '83 IT forks around, I did some searching for more information about this feature. According to Cycle Guide “The 43mm 1983 YZ/IT490 has a compression damping blow off valve that momentarily unseats and allows the fork to compress more easily when the wheel hits a big or abrupt bump. It is non-adjustable, unlike on the KX500 of the same year. The YZ wheel travel is 11.8 inches”.

As I also have a set of disc brake forks of unknow year, so I did some reading on thoses as well.

It turns out, the 1986 forks have 8-position compression damping adjustment. An alumite slider coating was used by this time “to reduce friction and oil contamination”. Fork action was give a favorable review in April ’86 issue of Dirt Rider. Another change came in ’87 with a new “travel control valve” or TVC. Unfortunately, TVC was given a poor review with Dirt Bike (1987) complaining of the “extremely harsh set of front silverware”.


What fork parts are shared across model years?

In the end, I wanted to use the best possible parts from the different fork sets I had. I compared part numbers for the various internal components and create this table to help spot which components were common between the model years.

In the table below, the model and year is labeled accross the top row and the part is labeled in the 1st column.


The letter A is used to denote the 1st version of the part for a particular row. The '81 model is the 1st fork considered so all the parts are of version A. If one looks at fork seals across all model years you can see they are all type "A" so this means they have the same part number and are interchangeable. The slide bushings and slide pistons are also shared across years.

If a part changes, say from A to B, across model years it means the part number is different and they may not be intechangeable.

Looking at the damper rod you can see they differ for every model year for the YZ. However the rod is the same for the 83 and 84 IT.




More to come I'm afraid


FJ_Kevin screwed with this post 03-26-2012 at 11:35 AM
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Old 03-23-2012, 09:10 PM   #33
Donkey Hotey
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Quote:
Originally Posted by FJ_Kevin View Post
As others have mentioned, the 1980 YZ465 used a 38mm fork with single leading shoe front brake. For 1981, Yamaha upgraded the 465 with a 43mm fork with double leading shoe front brake.
Nope, 1980 had the DLS brake as well. My bike was 100% bone stock in 1982 and it had one.

Edit:
This picture ran with the magazine test in--I think it was Cycle--in 1980 (duh, says so on his jersey). You can plainly see the brake.



Edit 2:
Hell, I forgot I had this posted out on the web. That's me with my bike in '82 or '83--Gold Belt, Hi-Points, Griffin pants--and a full head of hair.

Pretty sure that was a first generation Terraflex on the back and a Vesco desert tank.
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Old 03-24-2012, 07:13 PM   #34
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Wow, great pictures!!

The reason I like the old dirt bikes is all the rich kids had them when I was growing up and all I had was a DT125. I always sat in the library and read Dirt Bike magazines growing up. About 30 years ago..
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Old 03-26-2012, 11:58 AM   #35
FJ_Kevin OP
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[QUOTE=Donkey Hotey;18290928]Nope, 1980 had the DLS brake as well. My bike was 100% bone stock in 1982 and it had one.

Greg,
You are correct of course. Thanks for pointing this out. In looking back through the parts manuals I saw that the 1980 YZ250 has the single shoe brake and the YZ465 got the DLS as you say. PO stuck a SLS on my '80 465 at some point. I updated my previous post to fix this error. I hope you and others will chime in when you see a mistake like this!

And that is a very cool picture of you from "back in the day". Funny how skinny all the kids were back then... even if I still had all my old gear I would never fit into it now!

I hope you will post more of your old photos if you may have. Especially on your 465!



Here is one of me from 1978 on a '78 YZ125... Bell Magnum helmet, Scott goggles and face mask, viking jersey, Malcolm Smith boots, rubber strips on gloves. The bike as that cool JT cable guard thingy and the foam do-dads to protect the fork sliders... and the dog leg levers.

I am pretty sure I'm racing with a knee brace, bandages and torn ligaments on that left knee (duh!) this day. Still have my hair (most of it anyhow) but it is all grey now



Kevin
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Old 03-26-2012, 01:55 PM   #36
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Quote:
Originally Posted by anotherguy View Post
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.
That isn't a garage queen, it is a genuine OW factory machine. It probably has more hours on a track then any twenty YZ465s do all together!
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Old 03-27-2012, 08:46 AM   #37
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I was at Hangtown back when it was up by Placerville,It was early/mid 70's and Hannah was easily the most spectacular to watch,and fun to meet in the pits,friendly and easy to talk to. Danny Chandler showed up on a KTM 125 and was flat amazing,not a fast bike but holy jeeze could he fly that thing around with the throttle stuck open at all times!
I saw Danny Laporte snap the ft end off his works Suzuki.

We camped out with thousands of other lunatics in some farmers big field,huge bonfires,mini bike races all night,station wagon races,drunken bufoonery,what a blast!

Nice build on the 465!
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Old 03-27-2012, 01:52 PM   #38
supervision
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Hangtown , ealyl 70's was the high point of my racing. I finished high enough on Sat. 125 sportsman, so they let you ride, 125 Pro race Sun. I was so stoked, I hole shotted the first moto, even led for part way round!! WhenI came around the first lap people on the fence in the first turn, were cheering me on. Oh ya I rode Penton green fiberglass model,
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Old 03-27-2012, 02:42 PM   #39
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This is a topic that hits pretty close to home for me. I wanted one ever since
Marty Moates won the USGP in 1980 on the LOP YZ465.

Here is a photo montage of my 465 from back in '81. We had just got back from
the Western Pacific, and I put it together on the Flight Deck of USS Mt Vernon
by the light of a battle lantern.
The next morning when I got off duty, I rolled it up to the Quarterdeck and requested
permission to go ashore!

One of the bottom pics is it sitting on the pier.

Still ride it from time to time, way fun bike. Lots of power.




Here's an action photo of the bike taken near Carlsbad Ca, in 1981. Wonder if I still have that gear....



I will keep watching the thread for progress on yours!
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Old 03-27-2012, 06:29 PM   #40
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Thumb

You still have it? Original owner??

Sweet!
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Old 03-28-2012, 11:17 AM   #41
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- Foot dragger/Supervision: I think you two need to post a few pictures of your Hangtown days! Back in the northeast we had two events that were pretty wild... Unadilla and Loconia NH.

Saw many exciting battles with riders like Rodger D, Hannah, Jimmy Ellis, Pat Maroney, the KTM mounted Russians and others. Fans were very wild too. We made fake pit passes and roamed the inside of the pits and the track. Finally they caught us and turned us over to NY State Troupers on horseback to kick us out. They were nice guy though (and we were young) so they let us go!

Loconia in the early '70s was another very wild scene, lots of tits and naked women riding by and staggering around, motorcycle gangs, state police with dogs... a real eye opener at 11 years of age!

- Ctune: Those are very cool pictures. That is neat they let you put it on the ship. I too am impressed you still have it after all these years! Maybe you have a more recent photo as well? In any case, thanks for sharing these!

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Old 03-28-2012, 12:43 PM   #42
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43 mm Fork Upgrade Continued...

So to re-cap, I have spare '82YZ490, '83 IT490 & unknown year YZ490 disc brake forks to choose from in making the switch from the 38mm to 43mm.

In the end, I decided to go with the '83 IT490 forks. In addition to the 465, I also have an '83 IT490 and like the way the forks feel on that bike. Again, these forks have the blow off device that the '82 forks do not have.

Another factor in my choice is that I may try the Race Tech emulators in the future. The emulators would make the blow off valve in the '83 forks irrelevent. Because of this, I thought it best to hold back the '82 forks for the Race Tech modification. And I did not pursue the possibility of using the newer internals on the disc fork as I thought I might because of time constraints.

For kicks, I have listed damper rod part numbers across the model years. You can see they are all different.

Damper Rod Part Numbers
81 4V4-23170-L0-00
82 5X6-23170-L0-00
83 23X-23170-L0-00/ 26A-23170-L0-00
84 39X-23170-20-00/ 26A-23170-L0-00
85 56A-23170-L0-00
86 1LV-23170-M0-00
87 2HH-23170-L0-00

Now, we all know that sometimes parts will interchange even though the part number is different. I did not look to closely at this but did notice the damper bolt holes in the different year sliders were dissimilar enough to make interchange unlikely without doing some real work...

Moving on, here the brake side '82 yz490 slider is compared with the '83 IT490 slider. Interestingly, the bottom of the YZ slider is welded on whereas the IT slide is cast as one piece (like the '81 YZ slider). Another difference involves the axle. The YZ axle (top in photo) threads into the slider. The IT axle (bottom) slides through an unthreaded hole and is tightened with a separate nut. The IT forks requires use of the IT axle or machining of the YZ axle shoulder (on left) to match the IT design. Shortening this shoulder allows the axle to move further into the hub thereby exposing the threads per the IT arrangement.



Here are a few photos of the IT fork rebuild for the curious. The replacement seals are new from Yamaha.

I did not have a tool to keep the damper rod from spinning when removing the damper bolt. The air wrench was essential for overcoming this problem. I found it best to use repeated short bursts to get the bolt to back out of the slider without spinning the rod too much. Make sure you still have the fork spring installed as that is the only thing providing resistance to rod spinning.



Note: While the forks were apart I was able to fine a nut that fit into the hex on top of the damper rod.
This nut will be used to make a tool to keep the rod from spinning when doing fork rebuilds in the future.



Fork caps and springs.

Here is a comparison of three different fork caps and 82 YZ490 and '83IT490 fork springs.
Even though the parts are different in some way and have different part numbers, they are still interchangeable in the fork tubes.

Keep in mind though, the fork caps with the staight valves require use of the offset top triple clamp to keep the bars from interfering with the valves (my understanding is there are 3 versions of the top triple clamp for the 43mm forks).


See how overall length is the same for these spacer/spring combinations.



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Old 03-28-2012, 12:59 PM   #43
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Rear brake stay and expansion chamber.

I was a busy bee this weekend!

Recall that the YZ490 brake stay I was planning to use was longer than the yz465 stay (21in vs 20.25in) and this was enough to rotate the rear brake plate too far.

Solution: Mill off the end on the 490 stay, shorten the aluminum arm and then tig welded the end back on. To my surprise, the brake stay is hollow inside! It does feel pretty light.




Top left photo shows the hollow aluminum arm, trick! Top right is a flattering photo of me. Lower left is the arm after welding. Lower right photo is tab welded onto a YZ490 DG pipe I am using. I'll have more to say about the pipe and silencer in a future post.


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Old 03-28-2012, 01:39 PM   #44
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I have very few pictures of me racing, only a few, I have a hard time turning the computer, if you know what I mean. My Son has shown me a few times but later I can't repeat the same steps, so it goes nowhere. I have another story to tell, you might like. One of my friends I met thoughAHRMA used to be a team Yamaha mechanic, the other day I brought my little IT125 to ride as a pit bike at Holister ca race to spectate off of. He had never seen my IT125 before, and says the thing is so close to a ow27 hanha bike. He said at the end of the year they always turn the bikes to Yama but one year they buildt a spare bike out of parts, and left it with a large Yamaha dealer back east. They new they had to keep it hushed up, and be low key about it. So just a couple years ago he get a call from that dealer, and he says the Hana bike has a broke transmission and if he wants it, because he knows that he'd do the right thing with it. So he had to have a special gear made, and he restored the bike. He knew Bob was going to a some event in so. ca. and he waited though the autograph line to talk to bob. Bob say's, I seen you in the line, didn't think you'd want my autograph, what's up?? Bill took him around the corner, and say's look, your old bike !!!!
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Old 03-29-2012, 07:07 AM   #45
mrmustangman1000
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This really makes me wanna turn that old IT400 into a racer!
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