Clack Clack

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olChris

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My MK3 850 is the first Norton i've owned. I only did a few K's (haha K = .6ish of a mile) prior to stripping and was fairly confident (and still am) that the motor was/is in good shape..
I have "finished" refurbishment and debugging as i go with a few K's here and there (10-20) . I have also fitted a oil pressure gauge for piece of mind and runs at 60+psi cold and down to 40psi+ after 5 k's,.. (ambeant temp 30'c)

Cold start is ~20c and when initially firing up there is 3-5 clack clack's from the lower front of engine at idle rev's... i think lifters, put a few more rev's on it =1300rpm and the noise dissapears, let it go back to "idle" =8-900 rpm and a few moe clack clack's can happen.... this is all within the first few seconds from start up but once its been running for 5-10+ sec's and returned to idle <1000rpm it is sweet....

So question is ......... is it normal/common for 850's to clack clack at cold idle startup for a few seconds... ??????

Cheer

olChris
 
did you do any cylinder work during your refurbish?
new pistons, fresh Rings, Boring, honing, rods, wrist pins?
I guess my initial inclination would be piston slap.
 
+1 for piston slap.

What was your skirt to bore clearance? Cast or forged pistons?

Just to be through, what did you use for valve lash?

RS
 
Hi, I had owned an MK3 few years ago, and one day it makes a noise down under , but I found it was the primary chain tensionner which had not primed their oil (for whatever reason!! may be I had put ATF , I can't remenber it was 35 year ago......) but after priming the dash pot : problem solved.........hope this work for you, my two cents........!!
 
Best wishes trying to tell where a Commando noise is coming from just by listening. A sound bit here would help, maybe, but really only two ways to find out, run till it don't or open up and see what shows damage or misfitted. Loose nut in primary may be all it is, or lifter no seated.
 
marinatlas said:
Hi, I had owned an MK3 few years ago, and one day it makes a noise down under , but I found it was the primary chain tensionner which had not primed their oil (for whatever reason!! may be I had put ATF , I can't remenber it was 35 year ago......) but after priming the dash pot : problem solved.........hope this work for you, my two cents........!!
Click to expand...

I agree, hydraulic primary chain tensioner getting up to speed. Currently using 10/30 fork oil in the chaincase, seems to be working better than ATF. No problems with hydraulic tensioner, or clutch plates sticking after a few thousand miles, so far.
 
olChris said:
Cold start is ~20c and when initially firing up there is 3-5 clack clack's from the lower front of engine at idle rev's... i think lifters, put a few more rev's on it =1300rpm and the noise dissapears, let it go back to "idle" =8-900 rpm and a few moe clack clack's can happen.... this is all within the first few seconds from start up but once its been running for 5-10+ sec's and returned to idle <1000rpm it is sweet....

So question is ......... is it normal/common for 850's to clack clack at cold idle startup for a few seconds... ??????
Click to expand...

Yes, as it usually takes several seconds for the Mk3 hydraulic primary chain tensioner to re-prime itself, so the clanking noise you hear if the revs are allowed to drop is perfectly normal.
 
Just a posibility might it be if the primary chain adj. is fine: Tight valve guides from black gook caused by old man's disease is what it is. :wink: I have seen this so much on Norton's If you have big black flakes on your piston tops let the boy borrow the bike. :shock:
 
Don't let it worry you just ride it, if you take notice of all the little noise you will end up pulling your hair out, its a British bike they all make noises.

Just enjoy it.

Ashley
 
The anti kickback mechanizm makes a noise too ,,,,,, kind of a ratching clicking noise on my MK3. But only for a second or 2.....If you put your hand on the primary cover while someone else kicks it over you might be able to feel it....... :o



Tim_S
 
marinatlas said:
http://www.accessnorton.com/primary-noises-t10178.html#p113669
have a look.........
Click to expand...

That was an interesting read.......... I run ATF in the primary, cos the previous owner told me so and have seen it disscussed several times on this site..

I did start the bike this morning with camera in hand and, you guessed it , no noises/clack clack.... Saying no noises would be a lie :D :D :D ..

Reading through the above thread has highlighted "Primary Case" noise, and i must admit that this MK3 is a bit rumberly so the use of 20/50 oil in primary case, should quieten it down and maybe,maybe/should rid my clack clacks if it the tensioner !!!
 
L.A.B. said:
olChris said:
Cold start is ~20c and when initially firing up there is 3-5 clack clack's from the lower front of engine at idle rev's... i think lifters, put a few more rev's on it =1300rpm and the noise dissapears, let it go back to "idle" =8-900 rpm and a few moe clack clack's can happen.... this is all within the first few seconds from start up but once its been running for 5-10+ sec's and returned to idle <1000rpm it is sweet....

So question is ......... is it normal/common for 850's to clack clack at cold idle startup for a few seconds... ??????
Click to expand...

Yes, as it usually takes several seconds for the Mk3 hydraulic primary chain tensioner to re-prime itself, so the clanking noise you hear if the revs are allowed to drop is perfectly normal.
Click to expand...


Yes, and read your "quote" on another thread re 20/50 oil, Also Dynodave seems to be of the same opinion, as well as the "manual" so nothing to loose!!
 
OK so now have changed ATF to 20/50.. Maybe this is a dumb question and my observations incorrect :? :? , but, the primary chain tensioner get its feed oil/pressure from the oil pump (engine oil)... So how is putting thicker oil in the primary case going to assist the tensioner's workability apart from external surface wear ??.. :? :? I cant see how 20/50 will assist the performance of the tensioner :!: :!:
 
olChris said:
Maybe this is a dumb question and my observations incorrect :? :? , but, the primary chain tensioner get its feed oil/pressure from the oil pump (engine oil)...
Click to expand...

No, the tensioner doesn't get its oil supply from the pump, it uses the primary case oil, which is why it can take several seconds to re-prime after starting up.
 
OHHH Ok then will relook at it.. I'm now curious,to how it gets feed.... During my refurbishment i did not strip the primary case and internals down, consequently im very unfamiliar with it.. I did look at the manual "breifly" but show bugger all, tho i probably missed it (impatience when reading)...
Thanks LAB....
 
olChris said:
OHHH Ok then will relook at it.. I'm now curious,to how it gets feed.... During my refurbishment i did not strip the primary case and internals down, consequently im very unfamiliar with it.. I did look at the manual "breifly" but show bugger all, tho i probably missed it (impatience when reading)...
Thanks LAB....
Click to expand...

There's a 'trough' at the top of the tensioner partly formed by the steel plate. Oil drips/splashes into this from the chain whizzing round and gets sucked into the tensioner as the pistons move up and down due to chain movement/load. I found 20/50 too thick, good for the tensioner but tended to contaminate the plates causing sticking and slip.
 
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