Base gasket or no base gasket

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ashman

ashman

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In the last 2 rebuilds, both 750 Commandos engines I only used gasket sealent (3bond) under the barrels as recomanded in the workshop manual, but when rebuilding my own 850 I always used the base gasket, I am rebuilding a mate's 850 engine and just about to put the barrels back on so am wondering gasket or just sealant, the 750s are still oil tight after a few years back on the road and no problems with the base leaking using the sealent, my 850 has never leaked oil in 40 years of ownership and 3 pull downs but have always used a base gasket, so what is other rebuilders doing, gasket or sealent, barrels going on Friday afternoon so plenty of time to decide but thinking going the no gasket way, your throughts please.

Ashley
 
ashman said:
In the last 2 rebuilds, both 750 Commandos engines I only used gasket sealent (3bond) under the barrels as recomanded in the workshop manual, but when rebuilding my own 850 I always used the base gasket, I am rebuilding a mate's 850 engine and just about to put the barrels back on so am wondering gasket or just sealant, the 750s are still oil tight after a few years back on the road and no problems with the base leaking using the sealent, my 850 has never leaked oil in 40 years of ownership and 3 pull downs but have always used a base gasket, so what is other rebuilders doing, gasket or sealent, barrels going on Friday afternoon so plenty of time to decide but thinking going the no gasket way, your throughts please.

Ashley
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I used a gasket on my MK3, recommended by Jim aka.-comnoz. good enough for me.
 
I used to use a base gasket with anaerobic sealant on the 850's and just sealant on the 750's.

Any more I use a Cometic rubber coated steel gasket on both -with no sealant. It's just too easy and doesn't ever leak. Jim
 
Wellseal and no gasket for me.
Never had a base leak issue.
Lack of ability to retorque the through bolts makes me dislike the idea of a base gasket.
Just IMHO of course.
 
Fast Eddie said:
Wellseal and no gasket for me.
Never had a base leak issue.
Lack of ability to retorque the through bolts makes me dislike the idea of a base gasket.
Just IMHO of course.
Click to expand...

Same here plus some silk thread just for good measure even though only gravity drainage of oil it would be pain if it leaks. Clearance of cam followers to cam, valve to piston an pushrod length should be checked but the compression goes up about 1/2 a point which normally is a good thing an no cost or machining involved. Just check that head etc. have not been skimmed to much in the past.
 
comnoz said:
I used to use a base gasket with anaerobic sealant on the 850's and just sealant on the 750's.

Any more I use a Cometic rubber coated steel gasket on both -with no sealant. It's just too easy and doesn't ever leak. Jim
Click to expand...

Hi Jim

Very intrested to know more about the Cometic rubber steel gasket and where you get them from, can you also get them for a 650 Dommie, wouldn't mind to give them a go on my next rebuild, hopefully I will get to do some work on my Dommie motor after this rebuild.

I am glad I decided to start this thread and thanks to all who replied so far.

Ashley
 
Last time I used a factory paper gasket, it leaked like a sieve, so I re-did it using Locktite Plastic Gasket and it hasn't leaked since. The gasket Jim mentioned sounds good, but going with a sealant bumps up compression slightly with no other change. Never measured this, so it may only be a minute amount.
 
Cometic gasket has been around for quite a while. I keep a small stock of Cometic base gaskets or you can get them directly from Cometic.

http://www.cometic.com/

They have a rubber coating over a steel core making them strong and self sealing. If you put a bit of grease on the surfaces on assembly then the gaskets often can be reused. Jim





ashman said:
comnoz said:
I used to use a base gasket with anaerobic sealant on the 850's and just sealant on the 750's.

Any more I use a Cometic rubber coated steel gasket on both -with no sealant. It's just too easy and doesn't ever leak. Jim
Click to expand...

Hi Jim

Very intrested to know more about the Cometic rubber steel gasket and where you get them from, can you also get them for a 650 Dommie, wouldn't mind to give them a go on my next rebuild, hopefully I will get to do some work on my Dommie motor after this rebuild.

I am glad I decided to start this thread and thanks to all who replied so far.

Ashley
Click to expand...
 
I'll try Permatex Ultimate Grey Gasket maker Motoseal 1 on my Mk111 and this time around I'll try it without a base gasket. I like the idea of a slight raise in compression. And of course the 828's can't be retorqued after assembly , so I'm willing to try it this time. :)
 
All Mk1 850s came from the factory without a base gasket. I believe the base gasket was fitted to later models because the gasket goo occasionally blocked the head drain.

Dave.
 
No base gasket + Yamaslob #4; no leaks after a full Summer of riding, and no re-torque. However, I'll be going to one of Jim's rubberized base gaskets at the next teardown, because I hate cleaning surfaces that could have been joined without adding goop.

Nathan
 
Fast Eddie said:
Wellseal and no gasket for me.
Never had a base leak issue.
Lack of ability to retorque the through bolts makes me dislike the idea of a base gasket.
Just IMHO of course.
Click to expand...

+1
 
As you can see, there are many successful options.

I think it is very important to say that if you are going with a different option than you previously used, such going a no gasket when you used one before, that you remove any ridge left in the bore from normal piston wear. If this is a fresh bore, then no issues. If this is an old bore, then the ridge in the bore will raise havoc at the new position of the stroke, weather up top or down low depending on your particular difference.
 
CanukNortonNut said:
Just to throw another one into the mix...I use Loctite 518 without a base gasket. :p
Cheers,
Thomas
CNN
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Locktite 518 = anaerobic sealant - it dries in the absence of air. It works fine.

Use a pipe cleaner to make sure the return hole is clear. Jim
 
I went to the site but could not find a link to any Norton gaskets?....just V Twin stuff....................emailed them but no reply.........
 
manx850 said:
I went to the site but could not find a link to any Norton gaskets?....just V Twin stuff....................emailed them but no reply.........
Click to expand...

They make them up to order. Not enough volume to keep a stock I guess.

If you want one let me know. I keep then at .020 thickness. They are not cheap at $31.65 each plus postage. Jim
 
comnoz said:
CanukNortonNut said:
Just to throw another one into the mix...I use Loctite 518 without a base gasket. :p
Cheers,
Thomas
CNN
Click to expand...


Locktite 518 = anaerobic sealant - it dries in the absence of air. It works fine.

Use a pipe cleaner to make sure the return hole is clear. Jim
Click to expand...

A heads up on using an anaerobic gasket sealant ..... I had anaerobic sealant squeeze into the threads of the fasteners and lock them up. This was on the Monoblok float cover ,,,, one slotted head screw had to be drilled out. Perhaps this might not be a problem with a hex head bolt, but at least be aware of the possibility.

Slick
 
I would never use anything under the cylinders that could crush or change dimension - especially with bolt through cylinders that can't be retorqed without removing the head. If you ride hard in hot weather like I do then Loctite 518 and Permatex Ultimate Grey Gasket maker Motoseal 1 or Yamabond will still seep a stain of oil which isn't too bad. I haven't found the perfect solution. I may go back to contact cement allowed to dry on both sides before assembly. We used to use a couple coats of gasgacinch contact cement on both metal surfaces (also when using paper gaskets) - it was the ONLY way to keep our overheating BSA victor dirt bikes from leaking - but you had to pry things apart and scrape the surfaces on disassembly (lacquer thinner helps).
 
Well I still haven't put the barrel on yet was surpose to do it last Friday but my mate who has help me every time to put the barrels on (easier with extra hands) was a no show, but I have decided to go with the sealent way and no gasket, so thanks to all who replied, now I got to find a new mate.

Ashley
 
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