Correct gas cap gaskets needed for 1973 TX650

My immediate reaction was that there is no way 500 degree rubber is going to work as an exhaust gasket, at least not at the header. But then I decided to Google it. I can now confidently say that there is no way 500 degree rubber is going to work as an exhaust gasket, at least not at the header.
 
I thought I’d share the source that I just got my replacement seals for the 73-75 xs / rd caps. HVC Cycle has all 3 seals available. I’ve had good luck buying from them in the past. Just got my new seals today so I’ll have my hand at the install in the next few days.
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Please do. I got tired of trying to find or assemble the complete gasket set. Good to know there might be one that works for the 73 cap. I ended up using the one o-ring and it worked great. I've ordered stuff from hvc before. Great site.
 
Ok, I dug my parts out and sat at the kitchen island to go through them. Fortunately I had one assembled and another already disassembled. I armed myself with the exploded diagram that Skull posted above too. Both of these caps have been apart before. One was missing the little seal on the center post and the other had some kind of tarry goo there in It’s place. Anyway, I cleaned up the parts for the cap I was assembling and laid them all out, so here goes.... both caps fully disassembled and laid side by side.
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Reassembly will start with the parts just above the cap. The small rubber center post seal first, followed by the spring.
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Next is the top half of the 2 piece dished cups, then the round disc seal, followed by the bottom half of the 2piece dished cups to sandwich that seal in.
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finally the big main seal goes on. My cap initially had this seal installed upside down. I followed skull’s diagram and it makes sense. Then just pop the e-clip on and you are done.

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I will mention that some of these parts were a little tricky to get apart. The one cap had remnants of RedCoat sealer everywhere that was very hard. Just take your time and it’s not that bad.
 
I need to correct a mistake that I made here. I have the main cap gasket installed wrong. I figured this out today when something just wasn’t making sense when I tried to put the cap on my tank. The illustration doesn’t quite explain this but I pulled out a third cap I have and took it apart. While it was missing an inner seal, the main gasket was on correctly. Here is the cap I pulled apart
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Here you will notice on the inside of the seal is a lip/groove where something is to fit in there.
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Well the 2piece cups that are sandwiched together are supposed to ride inside that seal lip with the thin end of the seal squeezing against the bottom side of the cap and the thick end sealing against the filler neck.
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Here you can see it properly installed on the cap. Much better!
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sorry for the misdirection initially, but that’s how we learn sometimes.
 
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Man, this cap is turning into a rabbit hole. Something was bothering me about the smallest of the 3 seals that goes inside this cap on the center post (part #5). In the exploded diagram there is a random washer that does not have a part number listed. After doing some more digging through my spare parts, I found the old flat disc seal (#6) that I show in post #30 above has a steel washer inside the recess. You cannot see this because it it flipped upside down in the picture. The new seal does not come with this. My old seal was hard as a rock, so I cut the washer out with some scissors. Seal #5 needs to be pushed through the washer, then slid into the recess of the disc seal #6. Then the whole unit gets installed sandwiched between the cups with the small rubber seal #5 protruding through the hole and riding on the post inside the cap and spring.

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I got it all put together this morning before work but I was running late and did not take pictures. I will follow up with pictures later tonight. Essentially once its all put together and installed inside the lip of seal #7, it is all a single unit except the spring. Put the spring on the cap and slide the whole unit over the post and install the E-clip.
 
I need to correct a mistake that I made here. I have the main cap gasket installed wrong. I figured this out today when something just wasn’t making sense when I tried to put the cap on my tank. The illustration doesn’t quite explain this but I pulled out a third cap I have and took it apart. While it was missing an inner seal, the main gasket was on correctly. Here is the cap I pulled apart
View attachment 161745
Here you will notice on the inside of the seal is a lip/groove where something is to fit in there.
View attachment 161746
Well the 2piece cups that are sandwiched together are supposed to ride inside that seal lip with the thin end of the seal squeezing against the bottom side of the cap and the thick end sealing against the filler neck.
View attachment 161747
Here you can see it properly installed on the cap. Much better!
View attachment 161748
sorry for the misdirection initially, but that’s how we learn sometimes.
When I bought my bike it had the main seal #7 upside down so I assumed that was the correct way and installed that way again (look at the diagram you dumb shit!) I have all new rubber parts so it's time to assemble it correctly (No wonder it never sealed right it couldn't)
Thanks guys!!
 
Yep, mine was installed the same as yours. Totally explains why the PO had an issue after the repaint with gas that had leaked and caused a big bubble under the paint around the filler neck. The PO then just crudely cut the affected bubble out with a box cutter and tried to touch up with rattle can and clear. Totally F'd up what was a really nice paint job.
 
Man, this cap is turning into a rabbit hole. Something was bothering me about the smallest of the 3 seals that goes inside this cap on the center post (part #5). In the exploded diagram there is a random washer that does not have a part number listed. After doing some more digging through my spare parts, I found the old flat disc seal (#6) that I show in post #30 above has a steel washer inside the recess. You cannot see this because it it flipped upside down in the picture. The new seal does not come with this. My old seal was hard as a rock, so I cut the washer out with some scissors. Seal #5 needs to be pushed through the washer, then slid into the recess of the disc seal #6. Then the whole unit gets installed sandwiched between the cups with the small rubber seal #5 protruding through the hole and riding on the post inside the cap and spring.

View attachment 161769

I got it all put together this morning before work but I was running late and did not take pictures. I will follow up with pictures later tonight. Essentially once its all put together and installed inside the lip of seal #7, it is all a single unit except the spring. Put the spring on the cap and slide the whole unit over the post and install the E-clip.
I see what your saying about that steel washer (no part number) my old number 6 did have the steel washer imbedded in it
I need to take the cap apart and see if I can't get 5 and 6 and the steel washer put together as 1 unit
It just didn't look like you could push the steel washer inside 6
I may have both caps put together wrong
Time to open them both up and try again
Edit : The # 6 on my 75 I don't believe had the unlisted washer imbedded in it
God I hope I did't toss the old # 6 if I did I need to find another washer
 
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