Barrel Base Gasket?

Danno · Mar 27, 2019

Last base gasket I used (1984) leaked, so I have been using the sealant-only method ever since with zero leaks.

Deets55 · Mar 27, 2019

FWIW, Cometic makes a base gasket. Plug and play, leak free, and should be reusable. No worries about blocking the oil drain hole with sealing compound, and should release easily if de-construction is necessary. I used one on my primary, had it off twice for routine maintenance and still seals fine.
Pete

Hortons Norton · Mar 27, 2019

Deets55 said:
FWIW, Cometic makes a base gasket. Plug and play, leak free, and should be reusable. No worries about blocking the oil drain hole with sealing compound, and should release easily if de-construction is necessary. I used one on my primary, had it off twice for routine maintenance and still seals fine.
Pete

Pete where can you find them?? I looked on their site and can't find them. Special order?

Deets55 · Mar 27, 2019

You have to call them up. They have some stuff on file (computer) and will cut them special. I have been meaning to call them and see if they have the intake and exhaust valve cover gaskets on file. Give them some lead time, I think it took a week for the primary (MKIII) to come in.
Pete

Fullauto · Mar 27, 2019

The only experience I've had with a base gasket on my 850 was a bad one. Oozed out.

Ron L · Mar 27, 2019

KiwiNeill said:
I use Permatex Ultra Grey on everything that doesn,t use a gasket including crankcase, carb flanges and base of barrels, a 6-8mm stiff brush to apply in an even fashion and it gives you plenty of time to assemble.

Ultra Grey is an RTV silicone, that will cure in air and can get into the oiling system if you are not careful and use it sparingly. The Loctite 515, 518 products are anerobic and only cure in the absence of air, so stay liquid if squeezed out of a joint and will disperse in the oil. I have cleaned a number of cranks with little beads of silicone inside and separated cases with strings of silicone hanging from the inner surface. User beware.

CanukNortonNut · Mar 27, 2019

The 4 Cap screws running through the barrels which can't be touched after the head gets dropped on, is part of the whole clamping system to the latter Commando evolution barrels. Using 518 as Ron L suggests will set once in absence of air. The Paper gaskets have a tendency to move around once the engine heat cycles and vibrates. A 750 prior to the through bolts, can be re-tighten. Not so easy with an 850 barrel.
Cheers,
Thomas

concours · Mar 27, 2019

Just curious, as to why someone would want to use a gasket where the design was to not have one, reducing an already low 8.5:1 compression ratio even lower?

htown16 · Mar 27, 2019

Four bikes so far including an 850, all paper base gasket with 3bond on both sides, no leaks. Can't believe it would reduce the compression enough to notice. Have tried to remove gearbox covers and timing covers after using 3bond on both sides of a paper gasket. Had to beat holy hell out of them to get them loose.

Danno · Mar 28, 2019

htown16 said:
Four bikes so far including an 850, all paper base gasket with 3bond on both sides, no leaks. Can't believe it would reduce the compression enough to notice. Have tried to remove gearbox covers and timing covers after using 3bond on both sides of a paper gasket. Had to beat holy hell out of them to get them loose.

It's the Threebond that's sealing your barrel, despite the gasket.

Hortons Norton · Mar 29, 2019

Called Cometic yesterday and ordered head, base, and both intake and exhaust cover gaskets. He said they didn’t have the timing cover gasket, which I found odd. I have their gaskets on my Buell and have no leaks so far. The shop that did the work on the heads and barrels highly recommended them. I have no idea how they will work on a Norton. Have any of you guys tried their head gaskets?

baz · Mar 30, 2019

htown16 said:
Four bikes so far including an 850, all paper base gasket with 3bond on both sides, no leaks. Can't believe it would reduce the compression enough to notice. Have tried to remove gearbox covers and timing covers after using 3bond on both sides of a paper gasket. Had to beat holy hell out of them to get them loose.

If you have a gasket fitted you really won't need any sealent just grease on the gasket

Barrel Base Gasket?

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