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Keith1069
Joined: 10 Jan 2005
Posts: 239
Location: Hampshire UK
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 Posted: Fri Oct 17, 2008 6:16 am Post subject: |
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| It does sound out of tune but the noise is typical at least to my mind. If anyone has a copy of the National Motorcycle Museum rebuild DVD try listening to Norman White's NEW Production Racer motor (with it's PW3 cam presumably) Not clanky but very 'tappetty and ringy' if that makes sense. Would try to upload it but it's a VOB file and is copyright. Don't want it getting on YT! |
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jsouthard
Joined: 26 Jul 2008
Posts: 42
Location: Detroit Michigan
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| Posted: Mon Oct 27, 2008 10:45 am Post subject: |
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An update.
I just got the head off. One bent push rod and the others where scratched dent and worn down. This was the noise issue.
thanks for all your advice and help!
joe |
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Ron L
Joined: 27 Feb 2004
Posts: 1147
Location: Ohio
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| Posted: Tue Oct 28, 2008 3:33 am Post subject: |
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Joe,
Any idea what caused the damage? Pushrods don't just bend on their own. A recent mishandled head removal? Missed shift?
There might be further damage. If it was from over-rev (missed shift) you might want to check the valves to make sure they aren't bent and are sealing properly. |
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Cookie
Joined: 05 Oct 2008
Posts: 161
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| Posted: Tue Oct 28, 2008 7:16 am Post subject: |
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| This was years ago but it seems like whan I missed a shift and bent a push rod I had marks on the piston from the contact. |
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jsouthard
Joined: 26 Jul 2008
Posts: 42
Location: Detroit Michigan
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| Posted: Tue Oct 28, 2008 2:12 pm Post subject: |
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I'm still VERY new to this and not a mechanic.
Because of early carb problems i can't remember if it sounded this way when i bought it this spring.
This is the first head removal since i got it. I don't have the tools to take the spindles out or the valves. I may have Norbsa rebuild the head since he's close to me and the seasons over.
I want to do the work myself but with a lack of tools and when i start reading about "regrinding valves" i start to get nervous.
I'll post some pictures of the pushrods and the pistons. You guys may be able to tell me which direction to go. |
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jsouthard
Joined: 26 Jul 2008
Posts: 42
Location: Detroit Michigan
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| Posted: Tue Oct 28, 2008 2:49 pm Post subject: |
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splatt
Joined: 14 Jul 2008
Posts: 21
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| Posted: Tue Oct 28, 2008 9:16 pm Post subject: |
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| The bent push rods will be extremely noisy,is there any sign of the valves hitting any thing,ie piston.Check for loose valve guides as well,also head gasket leaking through middle,goodluck,let the spending begin&don`t tell mum. |
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Keith1069
Joined: 10 Jan 2005
Posts: 239
Location: Hampshire UK
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| Posted: Wed Oct 29, 2008 2:19 am Post subject: |
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| I may be wrong (often am) but the head clearance for the timing side inlet rod looks a little smaller than the drive side. Somewhere I remember reading that some heads needed relieving for the pushrods. I guess there will be clear evidence where it's been touching the head or barrel. I've overrevved my Combat to 7500 a few times over the years but never bent a pushrod yet. I'm sure Norbsa will sort it for you. Good luck. |
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Cookie
Joined: 05 Oct 2008
Posts: 161
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| Posted: Wed Oct 29, 2008 8:27 am Post subject: |
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| Arggh. I think I recall once putting in a hot cam that would have caused pushrod interference if I had not done a bit of grinding. Contact marks should be evident if that was the case. |
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tuono
Joined: 07 Nov 2007
Posts: 22
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| Posted: Thu Oct 30, 2008 4:19 am Post subject: |
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Wear ear plugs, works a treat on mine and no it has never let me down in 27 years.  |
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cash
Joined: 10 Nov 2006
Posts: 445
Location: west cumbria
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| Posted: Thu Oct 30, 2008 9:24 am Post subject: |
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Joe,
A bloody mess but not too expensive.
Did the noise start shortly after you set the valve clearances? Were any of the clearances large?
Cash |
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Cookie
Joined: 05 Oct 2008
Posts: 161
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| Posted: Thu Oct 30, 2008 9:31 am Post subject: |
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Forgive my ignorance but it seems to me I read somewhere of valve train geometry problems with some Commandos.
I never realized how easy I had it working on the old Atlas and early Commandos. |
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jsouthard
Joined: 26 Jul 2008
Posts: 42
Location: Detroit Michigan
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| Posted: Thu Oct 30, 2008 6:49 pm Post subject: |
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Cash,
The noise was there before any adjustments to the tappets.
The only reason i got in there was to try to eliminate some of the clacking. It didn't change anything.
Norbsa has the head now. I should find out soon if the valves are ok. It looks like the head may have been put back together by the previous owner poorly (bent pushrods, bent gasket).
I'll keep ya updated! |
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Cookie
Joined: 05 Oct 2008
Posts: 161
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| Posted: Thu Oct 30, 2008 7:03 pm Post subject: |
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This is what I'd worry about. It is possible you have a cam with more than stock lift that causes interference with a stock gasket at high RPMS. I think I see intake push rod contact on the pix but it is hard to tell. It would also be possible to over rev the engine and cause the same problem.
The chances of somebody assembling it with rods that bent are quite poor.
It is also possible that a non stock gasket was used without enough clearance. It is easy to put them together looking nice and have them come apart looking bad.
I'd make sure I have good clearance on the reassembly. |
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norbsa48503
Joined: 07 Apr 2004
Posts: 1034
Location: Flint, Michigan
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| Posted: Fri Oct 31, 2008 5:15 am Post subject: |
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| By the markings on the tips of the valves the push rod geometry was way off. The bores were stock 850, 3.0385 through and through. but no sign of the hone marks of old though. Still have to pull the valves to check the guide wear. The tappet faces look like just normal wear good news all and all so far. |
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Norton Commando Forum by Corporate Pages Web hosting using phpbb
The Unapproachable Norton Commando
At the end of 1967 the Norton Commando was announced.
The Norton Commando was greeted with a certain amount of scepticism because on first sight the commando appeared to comprise of the old Norton Dominator twin cylinder engine mounted at an inclined angle in a set of new cylinder parts.
It was not realized that the new Norton Commando Isolastic method of engine suspension damped out all engine vibration and produced a machine which had uncanny smoothness for a vertical twin. In due course the critics were silenced and the Norton Commando had the distinction of being regarded as the first of todays so called superbikes. There can be little doubt that the original design concept of the Norton Commando has proved correct, since comparatively few modifications of any real consequence have been made since production commenced during 1968.
Now nearly 40 years later Norton Commando riders like us are a breed of our own, and as far as we are concerned its still more fun to go for a blat on the old Norton Commando, and fast. As a Norton Commando owner and enthusiast, my goal here is to promote and give credit to those who keep the Norton name going.
It is more deserving to give credit to the Commando itself, for after all these years it continues to be respected. The original Commando designers like John Favill are those who deserve the credit for developing this incredible motorcycle.
The Norton Commando Roadster and Interstate of the late seventies, never died. Although the Norton Villiers factory dispersed the tradition lived on. Today Kenny Dreer in the USA is developing the new 952 CC Norton. What a great looking bike this is, and its engineering is still based on the original layout. It will be interesting to see how the new 952CC Norton does in todays tough motorcycle market. One thing is for sure, I would own one if I could afford it.
