Tin can full of nails!

Went out on the Commando last summer, it was to a local bike gathering. The weather for once was warm, when i stopped after a 40 minute blast, well i was with BIG bikes, Rocket Three 2.3 etc.
Point is when i got to park up the engine sounded like a tin full of nails being shaken :!: Made me cringe as this machanical rattle sounded quite loud.

where doe's all this rattling come from? Pistons. valve gear?
My Velocette is like a sewing machine compared to the norton. i know when the oil is hot ,it's ability to keep parts apart is lessoned.

All proper heavy twin Nortons make unsettling ringing clinking clicking rattle sounds, they just get a bit louder as stuff wears till it just don't run no mo. I've investigated this since '99, and can tell ya those syncopated high pitched sounds drive bats nutz if ya idle along slow enough they can cluster dive bomb the bike and pilot. The head is ringing like a bell from the rocker clappers as the major source - with the bing/bang/clang of thin header pipes getting hit with exhaust pulse as next. The cam chain drive is a rather sublte sound compared. I found exhaust wrap and wide IS tank cover up most the mechanical noises on the fly. Getting the header pipes dulled down makes a nice pleasant difference to hear only the engine mechanical sounds at front of bike and the deep note out the back w/o feelling like riding a trash pile hauling and scattering stuff on road side. But not to worry The stuff that actually falls off don't make much if any noise.

:!: Hey Steveo, i knew if anyone had a idea it would be you, but your answer is a bit general...where is the clatter when hot comming from? surely metal-metal is not happing.. Or is it?
the cam rotates towards the engine ,so any would be lube from the crank is just chucked off...right? is the "dribble" down the cylinder tunnel good enough, yes i know i am on the "OLD" lube path again.
I had a vincent twin that was totaly worn out, clanking,knocking .tapping and slapping all at the same time, i poured in two cans of STP whilest running, suddenly the engine went nice and smooth.....3-4 minutes..back rattling.
Once the STP had got hot, it's viscosity was lost..and the "gap" "space filling was gone ...I think straight 50 oil is the answer. or 140 gear oil :lol:

John, mine makes a lot of noise and to the point that I had the head and barrels off this winter to try and ID any sources. I found only badly worn exhaust valve tips, the usual thing on Commandos. I replaced the valves and adjusters and it is nicer, more of a liquid rattle than a tap tap tap etc. While waiting for new valves I mocked up an old valve shortened by 3mm to try and improve the geometry. When I realised I needed a minimum 4,5mm off the stem with lash caps and special longer pushrods I went no further. I think valve gear is the most likely followed by piston slap if your bores are worn/or clearances just simply on the generous side. I have a PW3 cam which runs 11 thou clearances but its not that bad (I have a video of a Norman White fire-up on a brand new PR for the museum and it sounds like the proverbial bag o' nails!) Tappets can get quite loose in the barrels and kick up a row. Has yours got a big mileage on it? Rebuild history etc?
Of course after a run at speed with the effects from wind and induction the ears seem to be more sensitive........everything sounds louder. I've gone back to earplugs, makes the whole experience more pleasant. You should try it with a fairing, now that really does amplify the clattering, rattling and knocking quite a bit. My gearbox sounds like its about to give up with its chattering and shunting in the lower gears, that too was stripped over winter and all ok, no excessive wear, all bearings good.
BTW, inserts are installed, engine back together and will be giving it a go when the rain desists.

Mine is so mechanically quiet that I sometimes wonder if it is full of sawdust. But then, I ride a Vincent quite often and they are generally a "noisy when hot " machine.
The 650ss is in the middle, definitely makes more engine noise than the Commando even though it has all new everything and the Commando has about 25,000 miles on, maybe more, it came with a broken speedo.
The solution for the Vincent was to get a straight thru exhaust and earplugs :mrgreen:

Glen

Keith.
Firstly the bike as a geunine 6000 miles on the un-touched engine.is this excessive..i suppose so if "Billy the Kid" as owned it :lol:

Mayby i should check the valve condition, etc.
Thanks for your responce.

Keith1069 said:

John, mine makes a lot of noise and to the point that I had the head and barrels off this winter to try and ID any sources. I found only badly worn exhaust valve tips, the usual thing on Commandos. I replaced the valves and adjusters and it is nicer, more of a liquid rattle than a tap tap tap etc. While waiting for new valves I mocked up an old valve shortened by 3mm to try and improve the geometry. When I realised I needed a minimum 4,5mm off the stem with lash caps and special longer pushrods I went no further. I think valve gear is the most likely followed by piston slap if your bores are worn/or clearances just simply on the generous side. I have a PW3 cam which runs 11 thou clearances but its not that bad (I have a video of a Norman White fire-up on a brand new PR for the museum and it sounds like the proverbial bag o' nails!) Tappets can get quite loose in the barrels and kick up a row. Has yours got a big mileage on it? Rebuild history etc?
Of course after a run at speed with the effects from wind and induction the ears seem to be more sensitive........everything sounds louder. I've gone back to earplugs, makes the whole experience more pleasant. You should try it with a fairing, now that really does amplify the clattering, rattling and knocking quite a bit. My gearbox sounds like its about to give up with its chattering and shunting in the lower gears, that too was stripped over winter and all ok, no excessive wear, all bearings good.
BTW, inserts are installed, engine back together and will be giving it a go when the rain desists.

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Oh I hadn't forgotten about the temps and oil thickness dampening metal-metal contact, but didn't mention as its not the source of the sounds and not effective to silence for long but for sense of how worn mal adjusted various clearances are. I put grease on my slide to help diagnosis how much that's messing with mixture, as washing out returns the symptoms in a less than a Roadster tank worth of gas.

My opinion is the primary ringing/dinging is the rocker adjusters tapping the valve stems which vibe though the guides to ring the dense-'hard' alloy of whole head. Next time doing a lash job open gap and flip at the rockers, next time head totally bare of anything but the valve seats, tap a screw driver on it, any where, and let that tone sink in forever more. Combustion also rings the head but softern than the rocker or push rod on lifter taps. Valves seating would also ring the head too. The exhaust pops into the thin pipes banging like tin cups clapped together rings back into head too - until they are wrapped up.

Ms Peel is a real odd ball to me, only similar sense of flying capet w/o fringe flapping was felt in Lexus LS 400 and a soar plane lack of engine sense for pure road texture or wind gusts and rush plus control forces got through. Nothing rattles shook or vibrated detectablly on Peel partly d/t most her attachment points had rubber under then and headers wrapped, IS tank with knees hugging it, I only heard the dulled deep bark of the long dong megaphone, up to 100+ then just wind.

I don't usually dally anymore on THE Gravel investing sounds to point bats dive in under helmet and get tangle in the headlight area wires and cables I have to help extract [old caver so bats are fine up close] so I've learned best to ignore, as sounds so very very similar to the sounds I've had as rod bolt let go, or slotted piston let go, or clutch nut or crank nuts came off or header ring nut loose or gasket blowing out, oil pump snout fractured, cam lobe leveled off... so every reason in the world to worry over head ringing sounds but a totally usless pastime that just makes ya an wearier worn worry wart.

Oh yeah the head lamp and forks can rattle head like as well as loose muffler on header fit.

At some point I'll have a digital sampler spectrum analyzer to send around the world for samples with suspected bike condition or faults listed then wait to see what fails then see what pre-signature showed up in that case but not others. Just for fun of course as nothing for it but dig in to see what's really going on. I'm continually surprised by posts asking what this or that noise is and then all the guesting in the dark long lists of things, then some weeks/months/seasons later we get surprise by a biggie found that none of us guessed.

[video]http://www.youtube.com/watch?v=MLIaqwS0kmM&list=UUPYptSBefG8VVdgykSJuXxw&index=40[/video]

Keith.Firstly the bike as a geunine 6000 miles on the un-touched engine.is this excessive..i suppose so if "Billy the Kid" as owned it

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Blimey that is not a lot, hardly run in unless as you say it's been well thrashed!! Maybe it has generous clearances all round or that's just the way it is. Similar to WT experience I have seen and heard 'quiet' Commandos but they are rare IME.

Mines got 24K on it and only had new rings fitted, idles like a sewing machine and no load noises when revved on the stand except out the exhaust.

Mine with 5k on it is quiet as can be. Much more so than my Triumphs, and the one has similar miles. what exactly do you set your valves to?

lrutt said:

Mine with 5k on it is quiet as can be. Much more so than my Triumphs, and the one has similar miles. what exactly do you set your valves to?

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Well as stated i have not opened up the "factory sealed" engine...note i said engine, we Brit's say British Bikes have engines..jap bikes have motors!

"Engines" use internal combustion to power them around, while "Motors" use external combustion or electric current developed outside the copper torque producing elements. A jet engine or an electric motor. Steam engines are odd exception to the rule in common parlance.

When I polished my rockers I noticed a definite increase in the ringing from the head.
You would be wringing the old gal out pretty hard to keep up with a Triumph Rocket III.

"Factory sealed engine" is not supposed to go to the extent of never setting the valve clearances !
Or setting the ignition timing.
Or changing the oil ??

Hmmm, has the engine got any oil ??

Do those, and see where that takes you.
Also check that the advance/retard function is advance/retarding.
Be worth checking too that your primary triplex chain is correctly adjusted - if its loose or bow-string tight, then not good...

Is it quiet when you start it up again from cold ?

Mine sounded like a coffee can full of bolts when the crank broke, but stayed together with interference fit till I got home. :shock:

triumph2 said:

When I polished my rockers I noticed a definite increase in the ringing from the head.
You would be wringing the old gal out pretty hard to keep up with a Triumph Rocket III.

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The guy on the Rocket III is a mate, i was using 3/4 throttle to keep up with his 1/4 , what made me smile was the Rockets rear tyre..OMG! Makes the 410 on the commando look "Peddle bike" .
i was the only geesa with a Commando in 1000 bikes , on the run a lad two up on a old GL1100 wing passed me, ..but not for long

john robert bould said:

like a tin full of nails being shaken :!: Made me cringe as this machanical rattle sounded quite loud.

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My Mk5 750 was rebuilt by the previous owner (a kiwi) with "the knowledge". It has 7000 miles since rebuilt and if you put your hands over the pipes, its quieter than a sewing machine. Barely a tick to be heard. If you have noise, you have a problem.

It has hi comp, goes like rocket and has solid idle at 600. Runs Mobil 1 Vtwin which may or may not contribute.

john robert bould said:

Once the STP had got hot, it's viscosity was lost..and the "gap" "space filling was gone ...I think straight 50 oil is the answer. or 140 gear oil :lol:

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If you are thinking about a straight weight 50 oil does that mean you are using a multi-weight dino oil? The viscosity index enhancers they use don't last very long. It can leave you with the lower winter rating after less than 1000mi, especially in an air cooled engine. 20w50 becomes 20wt. Try a quality synthetic like Redline 20w50.

You may have some serious wear on the valves where the tappet adjuster has worn a dimple or trough in it. When you set the clearance with a feeler gauge it can give you a much smaller clearance reading than if you measured the clearance with a dial indicator, which gives you the actual effective clearance taking into account the depth of the trough.

So you're saying it sounded like a CB 750.