Valve cover half moon rubber plugs, why needed?

[onchiman]

This might be a stupid question but just what is the reason for the half moon rubber plugs in the valve cover/cylinder head? I mean aside from sealing the hole, why can't we just permanently seal those holes up with something like JB Weld or fabricate a more permanent fix? I'm assuming that the reason those holes are there in the fist place is because they are leftover from the milling process of the camshaft seats. Has anyone ever tried some sort of permanent fix for this? Just curious.

[Nessism]

Why not just buy new half moon pieces if yours are leaking? Simple and effective fix. Good for 20+ years with no worry. I don't think there is any thing wrong with plugging permenently but it's way more work than necessary.

[Jaguarjoe]

Both my Jaguars have half moon seals in the back of the cylinder head. I replaced that rubber part with custom made aluminum ones. Other guys use "Marine-Tex" epoxy putty to make suitable plugs. No reason our bikes should be any different.

[onchiman]

Yeah, the next valve check, I think I'll try and seal them up and be done with the rubber plugs. Last set I had lasted 8 years before they didn't seal well anymore, which is pretty good. They are the weak link though, I've never had a "Real-Gasket" silicone valve cover gasket leak but it's always hit or miss with the rubber plugs. If the holes are filled and milled, I imagine the gasket could last indefinitely.

[Jaguarjoe]

I fired off an email to the guy who makes the Jaguar half moons maybe he'll make some Suzuki ones.

Are all of the camshaft bore half moons the same size across all of the different bikes we have or are they all different diameters?

[chuckycheese]

Why?

I was sort of interested in his initial question. I wonder why they do include those? I suspect nobody here knows but it would be interesting to know because it's certainly not easy to figure out by looking.8-[

[madjack57754]

Why they are there is when manufactured the cam galley is line bored. The machine tool runs all the way across. Cheaper to put rubber plugs in. You can buy aluminum plugs that seal in with a bit of sillycone, and add a dash of color

[Jaguarjoe]

Do you know who makes the aluminum ones?

[renobruce]

Do you know who makes the aluminum ones?

I just bought these for my project:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=004&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=140141579015&rd=1

[Nessism]

I just bought these for my project:

http://cgi.ebay.com/ebaymotors/ws/eB...141579015&rd=1

[renobruce]

Yup, that's them. I wonder if I can use case sealant (yamabond) on these. That would probably hold up better than gasket goo.

[Jaguarjoe]

Loctite 518 gasket maker would work well here.

[Nessism]

Yup, that's them. I wonder if I can use case sealant (yamabond) on these. That would probably hold up better than gasket goo.

Yamabond = Kawabond = Hondabond = Suzukibond = THREEBOND \\/

Should work. Not sure those aluminum bits will seal any better than fresh rubber ones but they do look cool. :-D

[renobruce]

Yamabond = Kawabond = Hondabond = Suzukibond = THREEBOND \\/

Should work. Not sure those aluminum bits will seal any better than fresh rubber ones but they do look cool. :-D

I'll give 'em a review when I get them. I like that they have a lip on both sides.

[onchiman]

I would be most interested in your report on these! That's exactly what I was looking for.