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Noisy Atlas engine

Submitted by chris_rogers1 on Tue, 22/03/2016
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Heavy Twins

I recently replaced the oil pump, idler gear and camchain on my 1964 ATLAS, i hoped this might quieten the engine a bit but not so. It starts fine, runs fine and still pulls like a train. Is the horrible 'tapping noise' just a feature or am i missing something ? Valve clearances all seem good, timing is good but engine incredibly noisy. Contemplating engine rebuild next winter any advice on good providers to get the core crank and bore work done ? Any ideas around typical rebuild costs ?

Thanks

Chris

Submitted by phil_hannam on Tue, 22/03/2016

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The Atlas engine is a bit of a rattler. This can be due to worn cam follower tunnels, piston slap and the valve gear if it is the early low pressure feed type.

This could be inviting the classic comment of 'if it aint broke' etc. I would suggest enjoying the easy starting and get up and go feature. If the vibes, at low engine speeds, get really bad then start thinking about a major overhaul.

Submitted by chris_rogers1 on Thu, 24/03/2016

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Phil thanks !

I guess i'm worried that something might 'let go' due to my ignorance of the various noises that it emits - if i recorded said clatters would you give me the benefit of your experience in what it might be ? No liability for consequences - just struggling with such a noisy engine to diagnose whether serious wear and tear or just typical noise.

Chris

Submitted by john_holmes on Thu, 24/03/2016

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I cured a noisy B40, the crank nut bottomed out and did not grip the crank pinion strongly so keyway opened up from the forward backwards of the valve gear. A new pinion and a proper washer cured the noise. Found it using a bid screwdriver held against my ear and various parts of the engine.

Submitted by phil_hannam on Fri, 25/03/2016

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John's message rings quite true. With the cause of a dodgy sounding engine noise not always coming from the same point as the sound. ie. imminent big end failures noises can be due to a loose alternator rotor. One inside the engine and the other outside. The engine metals can transmit and amplify sounds and sometimes hide their origin. The screwdriver and lughole method only generally works to some degree.

Likewise, Utube and Mobile recordings are often too distorted to give a true likeness. The best suggestion I can make is to try and get of someone with a lot of engine rebuilding experience and ask for an opinion. I would be the first to offer if it wasn't for my broken white stick and dodgy hearing aids.

Submitted by anthony_duffield on Fri, 25/03/2016

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Chris,

I run a 650SS not too dissimilar from your motor.

A noisy engine can be caused by numerous things but as a guide:

A warm engine ticking over; tapping noises probably valve train, cam followers, rocker gear, valve clearances. Rumbling could be the main bearings.

On the road; knocking when accelerating could be bottom ends.

On the road, rattily sound when de-accelerating could be little ends.

The above is a guide, if you are really worried check the oil pressure (you have just changed the oil pump) and make sure that you are getting plenty of oil up to the head.

You could just take it easy this summer enjoy the bike and pull it down in the winter for a good overhaul.

Good luck

Tony

 


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