Butterfly seals

[Tim Meaders]

I order asset from Ebay but they are smaller than the originals. According to the seller all
seals swell over time from the heat. I've never heard of this before. I've attached images
showing the seals I removed from my 1981 BS34's on the left of the seals I received.

Please share your thoughts on this.

Thanks.

 

[jetmechmarty]

Speaking for myself, I wouldn't use them. OEM seals are available.

 

[5twins]

That doesn't look like an original style seal, it looks more like one of these "quad" style o-rings .....

I've used them in the past and they do work, but that was on a spare set of carbs that doesn't see much use, so I can't attest to their long term durability. But, I only tried them years ago because I was looking for a cheaper alternative to the $5 seals MikesXS was selling. That was before I knew you could still buy them from Yamaha for like half that. Now, I only use real, original seals. I have found a cheaper source though, Suzuki. Same seal but about a dollar cheaper than Yamaha sells them for .....

http://www.boats.net/parts/detail/suzuki/S-13651-51010.html

 

[gggGary]

my luck with those mcmaster carr seals was not as good as 5twins removed and put in new stock seals. IMHO don't use those chalk it up as a cheap life experience lesson.

 

[jetmechmarty]

5Twins, you rock! Come to my rally!

 

[Tim Meaders]

Thanks everyone. I've ordered the OEM seals. I'll repurpose the sqr. seals somewhere else. (someday)

 

[xjwmx]

The videos all say put silicone grease on them, There was some discussion on that here. I think the best thing, personally, might be to clean the pocket they go in and the shaft with brake cleaner and a rag and q-tips, and after dry put the seals in with nothing on them.

The interesting thing is the butterflies themselves when you center them by flipping the shaft. Their screws have to be loose enough that the butterflies can move, yet tight enough that they won't move randomly on their own. Just a hair touchy Then from that point gradually tighten them fully

 

[peanut]

The videos all say put silicone grease on them, There was some discussion on that here. I think the best thing, personally, might be to clean the pocket they go in and the shaft with brake cleaner and a rag and q-tips, and after dry put the seals in with nothing on them.

The interesting thing is the butterflies themselves when you center them by flipping the shaft. Their screws have to be loose enough that the butterflies can move, yet tight enough that they won't move randomly on their own. Just a hair touchy Then from that point gradually tighten them fully

I found that it was also important to eliminate any excess lateral shaft play as well, or the seals may move and leak and the butterfly discs won't center properly.

 

[xjwmx]

You mean side-to-side movement of the shaft? How did you eliminate that?

 

[peanut]

I used one of the white plastic spacing washers/bushes from a scrap carb shaft and cut and sanded it until it took up all the sideways play in my shafts . I had about 2mm play so it was impossible to centre my discs . The discs were binding on the venturi walls near idle throttle position and caused a high idle before I eliminated the play

 

[TwoManyXS1Bs]

Mailman's experience:

http://www.xs650.com/threads/my-60th-birthday-present.47639/page-37#post-511934