New Member with 1970 Commando

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The timing cover has passages (remember the conical seal) for pressurized lube to the cam end and drive pinion bushings and the oil that drains from those makes a bath for the chain, sprockets and oil pump worm gear. The oil level is controlled by the height of the drain hole. Jim's mod drops the oil level, but yours drains it completely. Doesn't seem like a good idea to me.
 
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AGAIN.... so how do you think the timing chajn is lubed in the breather modification where people plug the holes in the timing chest ??? How could that modification have more oil distributed to the timing side than my modification does... being that their modification looks like this



.......... and my modification looks like this


How are they getting MORE oil to their timing side than I am?... Either we are both screwed because of the drain hole we've both drilled in the same place or we are both ok. Right??

If anything, my modification pumps oil into the timing side MORE than a crankcase with blocked oil passages to the timing chest... Right??...
 
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DogT said:
There were several threads about this and I'm still confused, except maybe about the hole down by the oil pump. I got Jim's sump breather several years ago, but we didn't know then the frame brace was in the way of it, so I sent it back.
Hi Dave,
I have one of the Jim's sump breather and works great.
Ciao
Piero
 

DogT

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But how did you get it between the engine and the frame brace? I could get it on, but when I wanted to change the oil and drain the crankcase, I had to remove the front iso and jack up the engine. Maybe I just should take that as part of changing the oil? I should try it again.
 
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DogT said:
But how did you get it between the engine and the frame brace? I could get it on, but when I wanted to change the oil and drain the crankcase, I had to remove the front iso and jack up the engine. Maybe I just should take that as part of changing the oil? I should try it again.
Sorry Dave,
I forget to say you that i fit it on a 1971 frame with the front cross over tube.
Ciao
Piero
 
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Oh boy,
thanks for all the good advices and hints regarding the engine breather.
Since my engine is already in the frame and only waiting for the cylinder head to get new exhaust threads,
I will leave it as it is. I will not drill any holes in my timing case or crankcase.
Must have been running in the stock configuration somehow...
BTW the first drops of oil are already on the workshop floor,
I filled the swingarm pivot with 120 grade oil ans it already found the way through the new o-rings.. :roll:
The gearbox filled with oil is tight so far.
 
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o0norton0o said:
AGAIN.... so how do you think the timing chajn is lubed in the breather modification where people plug the holes in the timing chest ??? How could that modification have more oil distributed to the timing side than my modification does... being that their modification looks like this



.......... and my modification looks like this


With the lower drain hole, startups would be with a dry timing chain. Not sure how that would work, long-term.
If it works, I guess it's good, but I don't see how the timing chest retains any lube. Seems like you're relying totally on breather mist from the crankcase and any oil would drain out the small hole near the pump, picked up by the sump pickup and pumped back into the tank. BSA racing experiments years ago showed running the primary drive in an oilbath made the drive chain run cooler, last longer and yielded a couple horsepower. I would think the cam drive would work the same, to a lesser degree. Dropping the oil level in the timing chest by drilling a hole level with the drive sprocket center still keeps the chain in a constant bath, but according to Jim, reduces the running temp of the timing drive while maintaining lubrication. I wish he would weigh in and tell me what I'm missing.
 
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Ok, it´s been a while since my last post but I made some progress in the meantime.
I managed to get the parts together from my basket case and surprisingly enough the bike is running!

[I've managed to correct the fist three image codes-but there isn't a fourth image in your photobucket album? - L.A.B.]



This was my mockup for the S-Type exhaust system.




My "testmule". With fibreglass tank and no sidecovers. Heatshields on exhaust also missing.
The metal roadster tank and sidecovers are in my friends paint shop waiting for "Fireflake Royalblue"!

Now a question:



Is this the correct lenght of the dipstick for the 1970 central oil tank? 11,2 centimeters or 4.4 inches ?
The tank is about half full and the stick is still dry?


Back to the workbench!

Hope the pics are showing now!
Uli
 

DogT

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Pics aren't showing up. I have 2 central oil tank caps (one original I know) and on one, the stick measures from the cap to the end 4 3/8" and the L mark is at 3 29/32" and the H mark is at 2 29/32 from the cap. Or in mm 112 for the length L=100mm, H=74mm. The other one is 1mm longer for all measurements. I tend to run mine nearer the L mark.
 

L.A.B.

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rivera said:
Is this the correct lenght of the dipstick for the 1970 central oil tank? 11,2 centimeters or 4.4 inches ?
The tank is about half full and the stick is still dry?
There are a few variations of dipstick lengths and markings however, "half full" isn't enough.
According to that dipstick I suggest you fill to the "L" mark or half way to the "H" mark maximum-but don't be tempted to fill it any higher. If the tank is overfilled then the excess oil will just blow out of the tank breather.
 
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DogT said:
Pics aren't showing up. I have 2 central oil tank caps (one original I know) and on one, the stick measures from the cap to the end 4 3/8" and the L mark is at 3 29/32" and the H mark is at 2 29/32 from the cap. Or in mm 112 for the length L=100mm, H=74mm. The other one is 1mm longer for all measurements. I tend to run mine nearer the L mark.
Then my dipstick is the correct lenght!
I know the oil level is a bit low, but it´s still testing..
 
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Well folks!
Back to the workbench!
During a short testride I noticed oil leaking from the cylinder head. I forgot to tighten the two front nuts between the
pushrod channels. One stud came loose so I had to fix it by using a recoil set.



I refitted the head with a new compsite gasket and it still leaking. Last hope is a copper gasket.



Also I could not shift higher than second gear.
So I had to pull out the gearbox by almost ripping the whole bike apart. Compliments the the constructors of the bike.. :x




Opening the gearbox I was surprised to find a rollerbaearing for the layshaft but a bit worn..



And as usual a cracked kickstart shaft..



And this is the proof: The bike was made for me!
They put my family name on the mainshaft bearing! :D



Cheers
Uli
 
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Take the cylinder to a machine shop and have it checked for "flatness".
A lot of 750 cylinders were not flat when new.
With a copper gasket it will not "blow", only leak. With a composite gasket it can "blow" at any time.
 

lazyeye6

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johntickle said:
Take the cylinder to a machine shop and have it checked for "flatness".
A lot of 750 cylinders were not flat when new.
With a copper gasket it will not "blow", only leak. With a composite gasket it can "blow" at any time.
I've used composite eyeletted gaskets on all 3 of my Nortons for considerable mileage and never had one blow.
Yes I've had oil leaks, but they were due to me not paying attention to the various tricks offered on this forum
to eliminate them. So, I guess a composite gasket could "blow" at any time, but then so could volcano. :p
 
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I've used composite eyeletted gaskets on all 3 of my Nortons for considerable mileage and never had one blow.
Yes I've had oil leaks, but they were due to me not paying attention to the various tricks offered on this forum
to eliminate them. So, I guess a composite gasket could "blow" at any time, but then so could volcano. :p
I was referring to 750 Commandos, not to 650 Mercury or 850 Commandos.
 
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Forgot to mention my cylinders are oversized .060 .
Heard there should be an issue with the metal eyelets of the composite gasket an the edges of the bore..
 
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o0norton0o said:
I just got this

I guess it is the same as your breather valve. Also from a XS 650
Did you leave the inlet side off and bolt it directly to the cover?
 
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rivera said:
o0norton0o said:
I just got this

I guess it is the same as your breather valve. Also from a XS 650
Did you leave the inlet side off and bolt it directly to the cover?
I did NOT use the inlet side of the valve casting. I DID bolt it directly to the cover plate. I actually bought a flat cover from Oldbritts because my original cover had a dished shape to it and it wouldn't work properly. Also, I drilled out the threads in the casting so I could use a thicker bolt with nuts in 2 spots, but I didn't drill out the hole that was closest to the rear because I didn't think there was enough material to widen the hole. This is what my mount looks like from the inside of the timing chest.

 
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That´s how I did it this afternoon.
My Norton already had a flat cover so it was easy to fix the breather.





There was already a venting hole right to the timing-chain spanner. I drilled the second one by use of a vaccum cleaner to keep the metal out of the crankcase
and drained the oil. Photo was taken before.

Next was removing the head (again). I will use a copper gasket. Together with the new breather I hope the oil problem will be solved.
 
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