New camshaft, new noise

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Dave F

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Jul 16, 2010
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I have just completed the re-build, new camshaft and followers. Bike starts and runs well (hooray). But of course there are noises. My question is about a primary side noise that I get on the overrun. It is definitely not knocking or chain hitting the cases but more of a "whine" that sounds rather like an old car reversing. The whine is related to engine speed. Is this just the upper run of the primary chain making noise while it is unloaded? If so should it be tighter or looser?
Advice and opinions appreciated!
 
Dave F said:
I have just completed the re-build, new camshaft and followers. Bike starts and runs well (hooray). But of course there are noises. My question is about a primary side noise that I get on the overrun. It is definitely not knocking or chain hitting the cases but more of a "whine" that sounds rather like an old car reversing. The whine is related to engine speed. Is this just the upper run of the primary chain making noise while it is unloaded? If so should it be tighter or looser?
Advice and opinions appreciated!
Click to expand...
Is your inner primary case shimmed properly?
Has the noise started since the rebuild?
 
baz said:
Is your inner primary case shimmed properly?
Has the noise started since the rebuild?
Click to expand...
Chaincase fitting is fine I believe - I have the Alton starter hence their inner chaincase. It took a while to get it aligned when I fitted that - but some time ago with no changes since
Is it a new noise? The million dollar question! I don't know about you but I am always super sensitive after making a change ... I am genuinely unsure. New? Old but louder? Old but different? I'll keep puzzling. Thanks
 
Either chain too tight?? you say engine speed can you determine if it engine speed (primary drive) or 1/2 engine speed (timing chain)
Do yo have an timing cover with inspection hole? taking this out and running the engine can be helpful, likewise with the primary cover upper inspection plugs removed this at least helps with narrowing the noise down
 
olympus said:
Either chain too tight?? you say engine speed can you determine if it engine speed (primary drive) or 1/2 engine speed (timing chain)
Do yo have an timing cover with inspection hole? taking this out and running the engine can be helpful, likewise with the primary cover upper inspection plugs removed this at least helps with narrowing the noise down
Click to expand...
Noise is clearly related to primary side, so I am confident that I am not looking at the timing side. Good point on running with the inspection plug out - hadn't thought of that! Something else to try. Thanks
 
The noise that you described sounds more like gearbox to me
Hence asking if it was a new noise
Has your layshaft bearing been changed? Any movement in the kickstart as you accelerate?
 
Dave F said:
Noise is clearly related to primary side, so I am confident that I am not looking at the timing side. Good point on running with the inspection plug out - hadn't thought of that! Something else to try. Thanks
Click to expand...
It's sometimes hard to pinpoint a noise
 
I just did a total rebuild on my 750 and now have what I would describe as a “whir” coming from the primary side. Changes include the lay shaft bearing upgrade to a roller bearing, two row primary chain from Jason, adjusted correctly, and a rubber backed timing chain adjuster, which if anything, made things quieter on the timing side. Never noticed the sound before the rebuild.
 
Dave F said:
I have just completed the re-build, new camshaft and followers. Bike starts and runs well (hooray). But of course there are noises. My question is about a primary side noise that I get on the overrun. It is definitely not knocking or chain hitting the cases but more of a "whine" that sounds rather like an old car reversing. The whine is related to engine speed. Is this just the upper run of the primary chain making noise while it is unloaded? If so should it be tighter or looser?
Advice and opinions appreciated!
Click to expand...
Can you tell if the whine is full or half engine speed? Is this a pre-72 750 - If so, it's possible that it's the breather disk or the drive side bushing (hope no in both cases!) If it's 73-73 then it could be the drive side cam bushing but I wouldn't think you could hear it.

I don't think the chain can whine if too loose, might if too tight.
 
It’s a ‘73, and I hear it at idle and on exceleration until wind noise drowns it out. I’m done worrying about it unless it gets worse, which it hasn’t in the past year since the rebuild.
 
marshg246 said:
Can you tell if the whine is full or half engine speed? Is this a pre-72 750 - If so, it's possible that it's the breather disk or the drive side bushing (hope no in both cases!) If it's 73-73 then it could be the drive side cam bushing but I wouldn't think you could hear it.

I don't think the chain can whine if too loose, might if too tight.
Click to expand...
Thanks Greg. Sorry I should have mentioned 74 Mk2a 850 which at least excludes the breather disk. I am working on the "chain too tight" theory since I did adjust it in the re-build. Currently adjusting it looser step by step, sounds better on the stand and hope to road test tomorrow
 
Loosened the primary right off (beyond any attempt to do it by the book). Good news on the road test - the whine is gone! I can now clearly hear the chain at slower road speeds presumably when it is "flapping" at certain rpm. Now to tighten it back up step by step .... Thanks for all the comments
 
To adjust the primary chain you should start with it on the tight side and loosen it until it's in spec. Tightening it step by step will cause the chain to tighten in use. Starting from tight will take all of the slack out of the adjusters so that it holds the correct tension.
 
triumph2 said:
To adjust the primary chain you should start with it on the tight side and loosen it until it's in spec. Tightening it step by step will cause the chain to tighten in use. Starting from tight will take all of the slack out of the adjusters so that it holds the correct tension.
Click to expand...
Yes indeed - I was meaning that I will "gan canny" with the adjustment and see how the current noise changes. Many happy hours of adjusting, road testing, adjusting etc. Hey! maybe I'll strike lucky and get it right first time... Thanks
 

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