NO leaks......

texasSlick said:

Just for the record, my Atlas sump plug hollow copper seal, part # 06-7680, measures 1 3/16" ID / 1.5" OD (30.2 x 38.1 mm). I supposed Cdo's were the same.

Slick

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Hi texasSlick.
If you or other Atlas owners (maybe standard Commando) decide on Dowty bonded seals for the big sump plug, the size reference is 029 (400-860-4490-41)
Ref: http://www.sealingaustralia.com.au/bonded-washers/
I recommend them as a vast improvement over copper washers.
Ta.

DogT said:

That was one of my goals when rebuilding my bike, but I didn't do a good job sealing the crank case flanges and that's where I'm getting leaks now. It wasn't bad when I had SAE50 in it, but now that I've put the 10W40 V-Twin syn in it, it leaves a pretty good sign. I didn't do the breather mod either, so I really should just pull it apart and re-do that part of it, I could probably do it in a week, with a few hours a day. I was just too confused at the time about the breather holes with everything else going on. That would give me the opportunity to put the JSMotorSports light weight pistons in it too. I'm just a bit concerned about the valve setup with that system.

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Ya sound pretty ambicious for an old coot, there Dave. I might think just changing back to 50w would do ya.
I have a lot of JS stuff already, but not the rods and pistons yet. If I had $1500 and a good reason to open it up again, I probably would too.

Many years ago when I rebuilt my crankcase, I had no clue about crankcase breather modifications, and I did my best to get all my surfaces mated tightly, gasket joints tightened down properly, and parts assembled without doing damage to newly installed seals. I still had some leaks that I couldn't completely stop or wasn't aware of the modification to fix them. (tachometer drive) So, I suffered with a bike that always ended up with a coating of oil on it from slow, persistant leaks because I didn't want to clean my bike everytime I rode it.

I was aware that there were guys who could rebuild a norton without any leakage. My buddy Paul, paid "Dr. Bob" in new jersey to rebuild his bike and it didn't leak way back in the 80's, so I knew it was possible. I'm not a professional mechanic, so I didn't have the "Dr bob" touch, and I had some leaks on my bike, but at least I rebuilt my bike myself.

I accepted that most nortons have some leakage and I was unaffected by all the classic comments like: "oh look, your bike is marking it's spot". My bike leaked! I accepted that....

......but I'm not stupid, and even though I didn't innovate the solution to certain problems of the commando design, I am smart enough to recognize good solutions. Many of which, I have added to my bike. Once I did the breather mod to my bike all the crankcase leaks stopped, and because my bike wasn't covered in oil, I was able to see that I had a gearbox leak too, so I rebuilt that recently also. I used a little silicone on the primary cover rope and bingo, dry bike... mind-effing-blowing....

For ME,.... the turning point was the breather modification which cured my minor crankcase leakage. Even though I didn't go for the comstock breather solution because I don't have the money nor the patience to tear down my bike again, I did "go to school" on his use of the reed valve to reduce crankcase pressure on all my joints, gaskets and seals... Hence, I am pretty happy to have a dry back wheel ...

I feel that with the help of the forum search function and the many people who shared their information here I am going to have a norton, that not only doesn't have an oily back wheel most of the time, but will soon be tracking very precisely at high speeds with the help of the new head steady I am psyched to add to my non-leaking bike....

I ran it up to 90mph today and it barely weaved at all, but my feet were buzzing a little because I had the isolatics too tight after reassembling the iso's after the gearbox rebuild and reinstall... I am pretty psyched.... as you can probably tell...

@Needling - Thanks for size info.

Dowty seals are hard to find in the US .... anyone have a source to buy in small quantities?

J&P cycles has them up to 12 mm ... larger I dunno where to get.

Slick

Hi texasSlick.
Do you want just the sump seal or a full bike set?
Ta.

You can seal em up so they don't leak a drop. But its hard to avoid weeping over time.

Use Rubber valve cover gaskets (Rocky Point cycle). RGM has some rubber gaskets. Or use as light sear of silicone on your paper gaskets and assemble before it sets (add an oil film to the mating surfaces so the gasket won’t tear on disassembly). Yamabond or “the right stuff” on case halves. Use fork gaiters to keep abrasives off the fork tubes so the seals last.

Upgrade to the following O Rings:

(Oring store #s)
1/16th by 3/8th OD viton clutch push rod seal (after market item for belt drives)
3/32 x 11/16 ID viton O ring shift lever - cram it in.
Tranny kick shaft - use quad O ring with 1” ID, 1-1/4 OD (QR 214) viton
Tranny cam & shift pawl use 3/4 OD x 3/32 viton (BV75113)

Seems like paper gaskets turn to mush over time from soaking up oil from the inside. No big deal on valve cover gaskets, but primary and gearbox gaskets should last until taken apart. My oil-tight gearbox started leaking at the cover gasket when the bike sat unused for years.

Some sneer at the red silly con rocker gaskets but I find them wonderful sealers with a slight red high light and saves the threads trying to seal by clamp force alone. I got two sets and have worn one set out on Peel and about to on Trixie - after dozens of re-uses. About 15 yr ago a major head of corporations that made UK gasket materials through the 60s-80s was convicted of using inferior materials like paper or plastics wastes so a big reason British iron both 2 and 4 wheelers got reputation They All Do That...

+ on the silicone with the paper valve cover gaskets. I glued them to the covers and just a smear on the engine side so they're removable. Still have to deal with the studs though, I put washers on the nuts and seal them also with silicone. Primary case O ring put in with small amount of silicone and a smear on the cover seems to stop that too. Easily re-done.

In this bikes early life it was a sea of caked mud/oil on the bottom of the engine back to the swing arm, and although it still leaks, not like then at all. Of course cutting off the chain oiler helped a lot.