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theroller1
02-04-2011, 9:59 AM
Hey Folks
I have a 74 norton chopper in a 72 custom frame. I am getting quite a bit of oil leaking out of the primary. It slings out off the chain and drip from below the primary when i come to a stop. Does anyone have any experience with these, and have an idea where my problem or problems may lie? It is a pre-unit, MKIII 850. Any ideas would be welcome. Cheers.

Torch
02-04-2011, 10:47 AM
Hey Folks
I have a 74 norton chopper in a 72 custom frame. I am getting quite a bit of oil leaking out of the primary. It slings out off the chain and drip from below the primary when i come to a stop. Does anyone have any experience with these, and have an idea where my problem or problems may lie? It is a pre-unit, MKIII 850. Any ideas would be welcome. Cheers.
the mark 3's have several places where they can leak, they changed a perfectly good working system for the left side shifter and the electric start. the mark 3's are easy to spot they have about 10 bolts holding the primary cover on, the earlier 850 commando has one large bolt on the primary cover and a "O" ring seal.
mostly they leak through the shifter shaft seals on the inside and outside primary cover and because of the paper primary cover gasket the leak there too. check the shifter shaft bushing to see if it is worn out.
by the way if it is a Mark 3 850 electric start it should be a 1975, otherwise is it a 1974 mark 2.

theroller1
02-04-2011, 10:56 AM
Then its an mkII... I thought it was an mkII but the guy I bought it from swore it was an mkIII. I researched it and its the last year of right side shift first year 850...Could it be leaking from the engine into the primary as well?and then out that o ring seal you were speaking of? Thanks!

Torch
02-04-2011, 11:13 AM
Then its an mkII... I thought it was an mkII but the guy I bought it from swore it was an mkIII. I researched it and its the last year of right side shift first year 850...Could it be leaking from the engine into the primary as well?and then out that o ring seal you were speaking of? Thanks!
then you have the easy one to get sealed up. they did have a habit of leaking around the paper gasket between the inner primary cover and the engine case. the bad news is you need to pull the whole primary assembly off and use RTV silicone around it to seal it up.
The primary cover rubber "O" ring is easy to get sealed up just order a new one.

theroller1
02-04-2011, 11:19 AM
COOL! so pull the primary...can I do this without removing the engine from the frame? I assume I should do this first, then replace the o ring for the cover. Also should I replace that paper gasket as well or just use the silicone? Thank you soo much... this is a great help!

Torch
02-04-2011, 11:29 AM
COOL! so pull the primary...can I do this without removing the engine from the frame? I assume I should do this first, then replace the o ring for the cover. Also should I replace that paper gasket as well or just use the silicone? Thank you soo much... this is a great help!

yea kinda like that, but it ain't no 1/2 hour job, you need to pull everything even the clutch basket. then the inner primary cover, it doesn't matter if you used the paper gasket or not it's the silicone that seals it.
now, hear this....Get a Norton service and repair manual, Norton's EXPLODE if you don't do the maintenance correctly.
A Triumph will run no matter what ham fisted monkey fucks with it, but not Norton's.

LinkBelt
02-04-2011, 11:36 AM
Hey who you callen a ham fisted monkey? LOL NO shit Tony thats going in the greatest quotes in the Junk pile.

Torch
02-04-2011, 11:58 AM
Hey who you callen a ham fisted monkey? LOL NO shit Tony thats going in the greatest quotes in the Junk pile.

I'm pretty sure that is verbatim right from the Norton manual.

theroller1
02-04-2011, 12:49 PM
Thanks for your help. Ill be sure I take my time and use the manual.
Cheers!

chopped850
02-05-2011, 11:12 AM
Dylan I only told you what I was told about the bike! I have a clutch hub spring compressor for that bike to make the job easy! Just give me a call man plus I still have those other parts for her that I found.