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-   -   Building a 1981 Yamaha YZ465 Factory Replica... (http://www.advrider.com/forums/showthread.php?t=772033)

FJ_Kevin 03-11-2012 09:22 PM

Building a 1981 Yamaha YZ465 Factory Replica plus Husqvarna & vintage racing...
 
*** Thread now expanded to include vintage Husqvarna's (around pg 23), vintage motocross (Unadilla) and cross country racing! ****

Hello Gents,

My interest in vintage motocross and enduro bike has really taken off the last couple of years. Right now I am rebuilding a Yamaha YZ465 with the ideal of participating in some VMX events this spring. My goal is to build a OW replica bike.

This is what I started with...

http://kgfphotos.smugmug.com/Motorcy.../IMG1305-M.jpg

That plus some other junkers got me to this point...

http://kgfphotos.smugmug.com/Motorcy.../IMG1621-M.jpg

Plus a lot more work to get to here...
http://kgfphotos.smugmug.com/Motorcy.../IMG1651-M.jpg

I hope to have a completed motor installed next weekend.

Finally, here's Bob Hannah at Southwick riding a factory OW
http://kgfphotos.smugmug.com/Motorcy...h79swick-M.jpg

D.T. 03-11-2012 11:17 PM

:wings

Sweet! Did they come with gold rims in 81'?

Euromad 03-12-2012 04:05 PM

Nice! Looking forward to seeing the end result. Big motor in that one.

FJ_Kevin 03-14-2012 10:46 AM

D.T., you are correct. The 1980 model came with silver rims and the '81 with gold. You have a sharp eye there!

In fact, the 1st bike I bought was a 1980 model. It was in such terrible shape that it has more or less morphed into a 1981 model as I have replaced so much of it.

In reworking the wheels I chose to stay with the silver as I am going with the earlier look overall.

One thing I have found it that 30+ years is a long time for these old motocrossers. The insides of most of the motors I have are screwed up in one way or another. Some are just plain worn out, others have been assembled incorrectly or hacked up in some way by previous owners.

Thanks too Euromad... it's been a lot of work but I have been enjoying it.

FJ_Kevin 03-14-2012 11:24 AM

As I have a pretty complete photographic record of my work to this point, I thought I would share a little more of the details for those who might be interested.

It turned out that the 1980 bike I started with was in far rougher shape than 1st thought. I found a considerable amount of frame corrosion under the tank and the seat rails were bent up pretty good from loop outs. One of the frame rails had cracked and someone did a pretty crappy job of welding it up.

I began to think it would be best to find a cleaner frame rather than repair the 1980 frame. Frames turn up fairly regularly on auction sites. After a little searching, I wound up with a nice straight 1981 465 frame for $100.

There are a few minor differences between the 1980 and '81 frame. The airbox mounts are different and the steering head is 1/2 degree steeper. The '81 model uses a longer shock reservoir and the reservoir mounts on the frame accomodate this diffference. It is also believed that the '81 frame is slightly lighter due to wall thinkness in some frame tubes however I did not weigh them.

Here is another view of this wreck.

http://kgfphotos.smugmug.com/Motorcy.../IMG1303-M.jpg

Rust in the frame tubes inder the tank...
http://kgfphotos.smugmug.com/Motorcy.../IMG1509-M.jpg

The '81 frame was stripped, epoxy primered, and painted with top quality Glasurit black paint. The Glasurit was left over from my BMW R100 repaint. Normally I would say this product is too expensive to use on a dirt bike but since I already had it on the shelf...

http://kgfphotos.smugmug.com/Motorcy.../IMG1479-M.jpg

http://kgfphotos.smugmug.com/Motorcy.../IMG1492-M.jpg

http://kgfphotos.smugmug.com/Motorcy.../IMG1507-M.jpg

Hannah again...
http://kgfphotos.smugmug.com/Motorcy...alifbobh-M.jpg

99Bandit 03-15-2012 08:09 AM

Looking forward to seeing this come along. Nice work so far. Have you had any problems finding replacement parts for this?

Donkey Hotey 03-15-2012 08:54 AM

Quote:

Originally Posted by FJ_Kevin (Post 18215179)

Yer' gonna' buy some of those sweet Scott boots and JT "Hurricane" gloves to wear when you ride it, right?
(I think I've still got those gloves around here somewhere)

FJ_Kevin 03-16-2012 08:45 AM

Jason,

Parts availabilty is pretty good overall. The yz465 seems to be very popular in vintage racing so there is pretty good aftermarket support. It helps too that the IT enduro bikes are very similar and share most parts. And it turns out that a lot of parts are the same for the 250, even some motor parts like the clutch basket.

Then there is the yz490, basically an evolution of the 465. I am finding that a lot of the 490 parts can be made to work on the 465. Sometimes the parts are directly interchangable sometime some effort is needed to make them work. The 490 has had a production run of ~10 years and so lots of stuff gets listed on ebay. There is still a considerable number of parts available from yamaha as well.

Greg,

Yeah I like those Scott boots too! However I do have a couple of pairs of High Points I still use. And I picked up a new pair of JT gloves... gives me all the protection I need when driving the mouse.

http://kgfphotos.smugmug.com/Motorcy...49-54280-M.jpg

FJ_Kevin 03-16-2012 11:38 AM

Reassembly:

With the frame fleshly painted, the next step was to move it onto the lift where I could start reassembly.

It turns out the airbox from 1980 is not a direct bolt in as some changes were made in the mounting brackets. Instead of changing the brackets I sourced an '81 box off the vmx site vintagemx.us. While the new box was in good shape overall, the rear bracket was missing (seems to be a common problem) so I milled a simple replacement out of aluminum plate.

By this time I had also ordered replacement All Balls brand stearing head, swing arm, wheel and crank bearing kits. I found these kits to be of acceptable quality with the exception of the swing arm bearing kit. I thought that one fell well short of the OEM in terms of fit and quality... more about that later.

Here is a few more photos of the build up...


Fitting airbox and inner rear fender...
http://kgfphotos.smugmug.com/Motorcy.../IMG1513-M.jpg

Here the steering head bearings and triple clamps are installed. New Yamaha OEM fenders are also bolted up.

I removed the old bearing races out of the frame before painting. This was a bit of a pain as I was unable to catch the edge of the races in order to knock them out with a drift.

I wound up welding a strap across each race and then hammered against that. I am happy to say the ALL BALLs replacement steering bearings fit well and seemed to be of good quality.

http://kgfphotos.smugmug.com/Motorcy.../IMG1526-M.jpg


Here are the various bearing kits from All Balls

http://kgfphotos.smugmug.com/Motorcy...09-48418-M.jpg

Making the missing airbox bracket.

I used a studded rubber mount together with the new bracket made from 1/4 aluminum. The one stud goes into the box where it is held in place by a large flat washer and nut.

The other stud goes into the bracket which is in turn mounted to the frame. The mounting is sturdy and I like the idea of having the old plastic airbox isolated against vibration and shock.

http://kgfphotos.smugmug.com/Motorcy...24-04231-M.jpg http://kgfphotos.smugmug.com/Motorcy...01-14740-M.jpg

http://kgfphotos.smugmug.com/Motorcy...04-49459-M.jpg


The next step was to install the swing arm. Before doing that I had some decisions to make regarding rear wheel options...

But first lets take a with Bob Hannah at Unadilla...

http://kgfphotos.smugmug.com/Motorcy...obhannah-M.jpg

anotherguy 03-16-2012 08:24 PM

Excel rims and Buchanons stainless spokes. I oughta take a new photo of the damn thing. This one's getting old.



Shocktower 03-17-2012 09:13 AM

Very nice :evil

wfopete 03-18-2012 02:25 PM

I'm currently rebuilding a G model 465. The previous owner did some good things but left plenty of work for me. I'll need to replace the swingarm bearings, what were the issues with the All Balls bearing kit for the swingarm?

FJ_Kevin 03-19-2012 08:14 AM

Anotherguy..."Excel rims and Buchanons stainless spokes"

I agree that this is the way to go... since I started this project I have bought another 465 (another story!) that came with this setup. The quality looks really great. However, I am trying to control my spending on this project as I have a other projects going on at the same time. :1drink

So instead I found some used parts here and was able cobble together a decent wheelset for reasonable money. I'll give some more details on that in a future post...


WFO Pete,

On the swing arm bearings... I guess I was expecting the replacement kit to replicate the OEM parts. In fact, they differ in quite a few areas. First, the OEM design uses needle type side/thrust bearing whereas the All Balls kit came with thrust washers (no needle type bearing). I already had some new needle type bearing I had picked up earlier so this did not upset me too much.

The second issue is the pivot pins. The OEM has a hard chrome plating, like a wrist pin. The internal needle bearings ride on these pins so I think it is important to have a hard surface. The All Balls pins did not have a chrome plate finish. Perhaps they are still hard enough, I don't really know for sure.

The 3rd issue is the rubber seals that go into the end caps. They seem to be too large and I was unable to fit the end caps on using these seals. Fortunately, I had a pair of used seals in good enough shape and put it back together using those.

There is something I liked about the kit also. The needle bearings that insert into the arm are wider than OEM. I think this is an improvement as it spreads the load over a wider surface.

I have seen cases where the pivot hole is ovalled a bit from poor maintainence or loose swing arm bolt, especially on the drive side. I think the wider needle bearing in the All Balls kit helps to overcome this problem if not too severe.

Here are some photos comparing All Balls with OEM parts to help clarify some of my description.

In this photo you can see the kit came with pivot pins, cartridge type needle bearing, plast bushings, inner seals, outer seals flat side thrust washers and dimpled side thrust washers.

http://kgfphotos.smugmug.com/Motorcy...22-45627-M.jpg



The yellow side thush washers from the ALL Balls kit are dimpled to hold grease. Compare this to the OEM needle type bearing to the right.

The large seals (upper left) seemed oversized and I could not make them work. The smaller inner seals fit fine, as did the replacement black plastic bushings. You can see the replacement pins do not have the hard chrome finish as with the OEM.

http://kgfphotos.smugmug.com/Motorcy...-27-1615-M.jpg

The needle bearings and plastic bushings press into the arm here. The hole in this arm is slightly worn at the edge. However, a tight fit was attained using the wider needle bearing in the All Balls kit. I dont think the narrow OEM bearing would have worked as well.


http://kgfphotos.smugmug.com/Motorcy...18-38434-M.jpg

So again, overall I am pleased with the All Balls kits even though there are a few short coming in the swing arm kit. And I did not mean to sound too harsh with regard to these kits as I do appreciate the vendors that still make parts available for bikes like ours.
:wink:
Kevin

Here's Hekki and Bob in 1978?

http://kgfphotos.smugmug.com/Motorcy...ikkolago-L.jpg

Donkey Hotey 03-19-2012 08:44 AM

Quote:

Originally Posted by FJ_Kevin (Post 18214917)
D.T., you are correct. The 1980 model came with silver rims and the '81 with gold. You have a sharp eye there!

There was more than that. IIRC, they changed at least the rear axle diameter in '81 and very possibly the front as well. Rear axles were known to bend and get stuck in the wheel on the G..

anotherguy 03-19-2012 09:07 AM

Nah the front axle is the same. I'm using the '80 axle in my '82 490 forks on my 465.


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