What do you use to seal a clamshell?

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Bob95065

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I got a MS290 from a local shop. The saw needs a piston. I haven't worked on a clamshell saw before. I was surprised to see sealant where there should be a base gasket.

What should I use to seal up the bottom end of this saw when I reassemble it?

Thanks,

Bob
 
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There's a product called Yamabond which is a liquid gasket maker.that is the better version of it. But also at your local "farm fleet" or hardware store there's a product called "permatex" and they have a gasket maker. That's what you need.

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I use Motoseal 1 by Permatex. Others use Yamabond, Dirko red, etc. It needs to be able to be in continuous contact with fuel.
 
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I use "Ultra Black" from Permatex... Get it at Wal-Mart and haven't had any issues on about a dozen or so clammies that I have worked on for people.

TFB
 
Dirko Red is the only thing we use as a sealant, as others have mentioned Yamabond etc are excellent products as Brad mentioned no Silicone.
 
black and copper silicone is the better types of silicone that are a little more fuel and heat resistant.i actually hate any kind of silicone unless its in boobies.lol i rarely use it unless i have to seal the exhaust on one of my bikes.
 
Ya haha I don't know what I was thinking. Half asleep I guess. (Yes I did know that silicone doesent hold up to gas)

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Ultra Black is an RTV Silicone and is not recommended for this application.

Thanks for the input. It specifically states fuel resistance on it. Hasn't let me down yet. I've been using it to seal cylinders to cases as well. Maybe it will lead to failure down the road, but I haven't had any issues thus far.
Just curious, but what is Yamabond made of?
 
You may want to go back in and replace it with one of the above mentioned products.

Well, that is all me could find at the autoparts store.

It says its gas, oil, and grease resistant, and have used it before on other things, but this was a first on a chainsaw..

Seems to have worked so far, but guess I should change it?
 
Dirko special sealant
Dirko Silicone Sealant is a high strength permanently elastic universal sealing compound that seals surfaces, gaps, and cracks. Stops leakage of oil, water, and air. Resistant to ozone, sunlight,extreme weather conditions, hot and cold water, sea water, greases, mineral oils, aliphatic hydrocarbons,detergents and others. Temperature range from -122F to +356F.

Yamabond® 4 Marine

A silicone-based liquid gasket that fills gaps on a flange surfaces, when cured (sets in 3 minutes), this product forms a rubber-like gasket that resists high temperatures and seals joints, oil resistant, Use where the service manual specifies "Threebond 1208 B"



I think all of the sealants mentioned are actually silicone based... Just make sure the one you choose is heat/fuel/oil resistant.

TFB
 
The first one I did I used Seal-All, which worked fine but it sets up hard and is not fun to remove if you take it apart again. Then I stopped by the Yamaha dealer and picked up a tube of Yamabond4 at the parts counter for $10. Good stuff.
 
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