Look in between the flanges on one of the spokes. It's not actually on the rim.Wasn’t aware of that stamping.Interesting.Good to know.
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81 Special
- Thread starter GLJ
- Start date
Yes, on one of the spokes. Here's an '81 drum rear .....
Cleaned up the rear wheel. Came out pretty good.
Installed new brake shoes also removed and cleaned up the brake cam shaft. Reinstalled with fresh grease. Put some oil on felt washer.
Installed new brake shoes also removed and cleaned up the brake cam shaft. Reinstalled with fresh grease. Put some oil on felt washer.
Parts had come in for gas cap and petcock. Replaced the gasket on the gas cap.
Then worked on the petcock. It's a vacuum petcock never worked on one before. Read threw a thread on rebuilding them, seemed pretty straight forward. Cleaned all the parts up, went over the flat surfaces on a flat surface with sand paper until they looked good. Used 120 grit then 600 and finished them with 1200. The kit looked nice even has a new diaphragm. It came from Norway. So I put it all together, it looked good. Shame it didn't work. It would not seal the outlet. Took it apart looked everything didn't see anything wrong and reassembled. Same damn thing wold not seal the outlet. WTF. Took it apart again. This time I found the problem. On the new diaphragm assembly the distance from the the diaphragm to the o-ring is 1mm less than the old one. The o-ring could not get to its seat. Both rubbers on the old one looked good, no tears and still flexible, the o-ring on the other hand was as hard and stiff as a you know what was on your wedding night. So I used the o-ring off of the new diaphragm on the old one. Put it all back together and using air it tests good. Can't test it with gas until I finish cleaning the tank. Question is the filter assy backwards as I have it sitting on the petcock in the picture?
Then worked on the petcock. It's a vacuum petcock never worked on one before. Read threw a thread on rebuilding them, seemed pretty straight forward. Cleaned all the parts up, went over the flat surfaces on a flat surface with sand paper until they looked good. Used 120 grit then 600 and finished them with 1200. The kit looked nice even has a new diaphragm. It came from Norway. So I put it all together, it looked good. Shame it didn't work. It would not seal the outlet. Took it apart looked everything didn't see anything wrong and reassembled. Same damn thing wold not seal the outlet. WTF. Took it apart again. This time I found the problem. On the new diaphragm assembly the distance from the the diaphragm to the o-ring is 1mm less than the old one. The o-ring could not get to its seat. Both rubbers on the old one looked good, no tears and still flexible, the o-ring on the other hand was as hard and stiff as a you know what was on your wedding night. So I used the o-ring off of the new diaphragm on the old one. Put it all back together and using air it tests good. Can't test it with gas until I finish cleaning the tank. Question is the filter assy backwards as I have it sitting on the petcock in the picture?
Cool thread and REALLY nice bike, GLJ! What a score!
Also late this afternoon the package from China with the carb kits showed up. Kits look pretty nice. Not going to use the jets as I bought genuine Mikuni jets. The floats do not have a sleeve in them for the pin but its as good a fit as any BS38 that I have worked on. The float pins in the kit are different and will not work. No head on them and they are the same size on each end plus shorter.
Tomorrow I plan on assembling the carbs. I do have a question. Gary posted a pic of how not to put the pin in. What is the best way to put it in?
Tomorrow I plan on assembling the carbs. I do have a question. Gary posted a pic of how not to put the pin in. What is the best way to put it in?
I push the pin in by hand as far as it will go then gently tap it in the rest of the way with a 4oz. ball peen. You don't need/want to tap it all the way in, just enough so it comes flush with the outside of the other post. It'll end up about like so .....
And those pins that came in the kit may work, even though they don't have a head on them. Once the float bowl goes on, it effectively blocks the pin from coming out .....
And one more thing - if you use the originals with the heads on them, insert them with the heads towards the inside. That way, if you need to tap them out in the future, you'll be able to get the pin punch on them and swing the hammer without needing to split the carb set apart.
And those pins that came in the kit may work, even though they don't have a head on them. Once the float bowl goes on, it effectively blocks the pin from coming out .....
And one more thing - if you use the originals with the heads on them, insert them with the heads towards the inside. That way, if you need to tap them out in the future, you'll be able to get the pin punch on them and swing the hammer without needing to split the carb set apart.
Support the back of the post nearest the head before tapping in the pin.
Or the same water pump pliers with the other jaw on the back of the near pin works fine. Waterpump pliers cuz the jaw ends offset a bit.
Yeah if you don't home the head a side cutters will remove it easy peasy.
Or the same water pump pliers with the other jaw on the back of the near pin works fine. Waterpump pliers cuz the jaw ends offset a bit.
Yeah if you don't home the head a side cutters will remove it easy peasy.
I would agree cause my '78 is not stamped and does no have the internal lip for when tire goes flat to hold it form slipping off.
The new pins are shorter. I measured the bowl and posts and it looks to me like a end could fall out. I'm going to reuse the old pins.
OK something bothered me, the deal is: Yamaha had tubeless rims but didn't add the safety ridge to the rim till later. It keeps the tire out at the edge if it's deflated. I think Honda may have pioneered that ridge, they even added it to tube type rims. It may have saved my life on a shadow one time.
Found here: https://bmwmotorcycletech.info/section6.htm
The early Yamaha tubeless rims are like this one
Later (post XS650) late 80's?
They added the safety bead.
like this.
If the bead of a deflated tire drops down into the center it can come completely off the rim before you can get slowed down.
Some aftermarket rims being sold STILL don't have safety beads.
Yup run into that short shaft thing before.
There's a trick... I'd PM it, but it takes a practiced hand to work. If the screen assembly is a loose fit in the petcock, a bit of shim from a pop can will help keep it in place. Falling off happens, no screen, no reserve, when it does.
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A few years ago, this was hashed out at XS11.com. The data is all saved at XS11.club. As I recall, the “TUBELESS” safety rims came installed on the bikes during the 1979 model year. All 1980 and later Yamaha motorcycles had them.OK something bothered me, the deal is: Yamaha had tubeless rims but didn't add the safety ridge to the rim till later. It keeps the tire out at the edge if it's deflated. I think Honda may have pioneered that ridge, they even added it to tube type rims. It may have saved my life on a shadow one time.
Found here: https://bmwmotorcycletech.info/section6.htm
The early Yamaha tubeless rims are like this one
View attachment 259751
Later (post XS650) late 80's?
They added the safety bead.
like this.
View attachment 259752
If the bead of a deflated tire drops down into the center it can come completely off the rim before you can get slowed down.
Some aftermarket rims being sold STILL don't have safety beads.
yeah would like to see that. that safety bead came later than tubeless IIRC
https://xs11.club/forum/maintenance...e-between-tube-and-tubeless-wheels#post535342
I believe there are a few threads on it, and I believe you are correct, though I’m not 100% on that fact.
I do not remember what the length of the old one was that I reused. I do remember it was roughly 1mm longer from the diaphragm to the o-ring. I did not compare the overall lengths because I didn't care, I had found the problem. I'm guessing that the overall length was longer also. Not going to take it apart again to find out for sure. I looked in Partzilla and they do not show a part number for the diaphragm so Yamaha must have used different valve bodies during the production runs. I checked 80 and 81, I did not check all the years. I guess back in the day if you needed one you had to buy a whole new petcock.
