• Husqvarna Motorcycles Made In Sweden - About 1988 and older

  • Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Cylinder base gasket leak

390wr Jon

390wr Jon

Husqvarna
AA Class
Put a new piston in my 1980 390WR and installed a new base gasket (from Hall’s) during cylinder reassembly. After properly torquing the cylinder head I now have a leak at the cylinder base gasket during a leak down test. Does anyone use a gasket sealant for this gasket? If so, any recommendations on the sealant to use?

Any insight would be appreciated.

Thanks,

Jon
 
Much discussion about installing dry or with some type of sealant. Some suggest a bit of grease, some will use a light coat of spray paint. Typical sealants used are Yamabond, Threebond, Permatex, etc (make sure it is the fuel resistant version). The important part is to use a very light coating - don't want bits of 'goop' in the crankcase. The drawback to using sealant is it makes removing the cylinder in the future a bit harder.

First though, it might be useful to figure out why there is a leak in the first place. I've seen a mismatch at the case junction causing a leak. Using something very straight, i.e. a machinist ruler or other, see if the case / cylinder mating surface is flat - both on the case and the cylinder. Using "Scotch-Brite" (Non-Scratch) or 600 wet/dry to ensure the mating surfaces are clean is helpful also.

Let us know how it progresses.
 
For base gaskets and intake manifolds I've used Permatex Permashield Fuel Resistant Gasket Dressing & Sealant for years. I smear it on all contact surfaces as thin as possible. It stays gooey and cleans up with acetone/brake cleaner. If anything leaks its like Vinskord said, check the base gasket deck where the center cases meet.
 
Crash,

I followed your suggestion and used the Permatex Gasket Dressing and problem solved (I never used a sealant on the cylinder base gasket before ). It now passes a leak down test and starts on the first or second kick. My fingers are crossed that it behaves prospectively after 2 years of troubleshooting.

Thanks again and I hope you have a nice 4th.

Jon
 
Glad to hear the good news. Another benefit of that product I found was the ease of cleanup for whoever takes it apart next time. Acetone makes fast work of it and in my experience the base gasket has always been salvageable. Nothing sounds sweeter than a big bore firing on the first or second kick when cold. :banana:
 
I have not had to use any on my machines although some seem cantankerous to start.
Might try it on a pesky starter!
Thanks Jon and Daryn.
Happy Independence Day to All !!
 
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