Evening all, I have noticed that my bike is making a rattling noise it's hard to hear in this video but it does it a few times such as 24 seconds in. Any ideas what this could be? Cheers

http://youtu.be/yX_EYcqYkJg

That's hard to hear anything nasty in there mate.

Yeah, i can't hear anything either. Having said that it may well be cam chain shimmy.
One cylinder is probably running faster than the other at idle, causing the cam chain to slap against the chain guide in the head. You could try adjusting the fuel screws to equalize the two cylinders. I had this problem with my engine.

Quote from: crackin on January 28, 2016, 03:18:11 AM
One cylinder is probably running faster than the other at idle
I had this problem with my engine.

Hmmmm.... when you consider both cylinders share the same crank that's a pretty unusual fault condition but hey...........you live and learn all the time 

I think what you are trying to say is that it may be beneficial to sync the carbs 

Quote from: sledge on January 28, 2016, 07:01:48 AM

Quote from: crackin on January 28, 2016, 03:18:11 AM
One cylinder is probably running faster than the other at idle
I had this problem with my engine.

Hmmmm.... when you consider both cylinders share the same crank that's a pretty unusual fault condition but hey...........you live and learn all the time 

I think what you are trying to say is that it may be beneficial to sync the carbs 

No, it's not unusual at all it's quite common. Yes both pistons do share the same crank but if one cylinder isn't firing as hard as the other at idle the crank speeds up as one cylinder fires then it slows down because the opposing cylinder doesn't fire as hard causing the cam chain to loosen. Then when the good cylinder fires again the cam chain tightens causing it to slap on the cam chain guide. Pretty straight forward stuff i think.
  This may or may not be the OP's problem but i thought it was worth a mention.
Balancing the carbs is certainly beneficial but the symptoms of carb imbalance is vibration at higher revs, also caused by one cylinder firing harder than the other. Can you see a pattern here? Is this starting to make sense?
I see so many people trying to tune twins by setting both fuel screws exactly the same. Well that is not tuning at all. In-fact its a total waste of time. You need to balance the cylinders at idle using the fuel screws or you get all kinds of noises.
At the end of the day you can believe what ever you want to.

So what is the purpose of the flywheel?
Isn't it there to smooth out and damp any imbalances in crank speed between ignition strokes?

Can all that inertia contained in the rotating  masses, flywheel, balance shaft, cranks, cams clutch, transmission, wheels allow those parts to slow down in unison and then speed up again between strokes by an amount significant enough to be noticeable and have a detrimental effect in what amounts to 20 times a second at tickover  (and at about 180 times a second at redline?)

I can accept there could be an imbalance in force between cylinders on their respective combustion strokes, meaning one cylinder is doing far more work than the other, hence the suggestion to sync the carbs and balance that force out but I cant accept there will be enough of an imbalance in force between cylinders to alter the crank speed by a significant amount in the time involved......unless maybe the cylinders are not firing evenly and at 180deg apart or the bike is for whatever reason running like a total bag of shaZam!, which from the video...... obviously isn't

Come on......convince me otherwise 

I can't notice any unnatural noises.

Like i said Sledge, you can believe what you want.
I'm trying to help Jimbob, all you are doing is giving me shite.
If you are so full of knowledge, experience and skill, then please go ahead and help Jimbob with his problem.

Hey crackin, it's one thing to throw around theories.  It's another to get defensive of your theory when someone asks legitimate questions about it.

Your theory sounds neat in principle but seems unlikely to be quite common. I for one have never heard of cam chain shimmy.

To the original poster:
I can't hear anything out of the ordinary in your video, perhaps the camera wasn't capturing the noise?  Does the rattle sound only happen in neutral?  Does it increase in frequency/volume along with the engine revs?  Has the engine performance changed noticeably?

Try to isolate the sound, left side/right side, head/case/transmission.  Look for loose components.  Check your valve clearances.  Check your oil.  Start with the most likely things and work your way out to chain shimmy

Quote from: sledge on January 28, 2016, 03:22:54 PM
So what is the purpose of the flywheel?
Isn't it there to smooth out and damp any imbalances in crank speed between ignition strokes?

Can all that inertia contained in the rotating  masses, flywheel, balance shaft, cranks, cams clutch, transmission, wheels allow those parts to slow down in unison and then speed up again between strokes by an amount significant enough to be noticeable and have a detrimental effect in what amounts to 20 times a second at tickover  (and at about 180 times a second at redline?)

I can accept there could be an imbalance in force between cylinders on their respective combustion strokes, meaning one cylinder is doing far more work than the other, hence the suggestion to sync the carbs and balance that force out but I cant accept there will be enough of an imbalance in force between cylinders to alter the crank speed by a significant amount in the time involved......unless maybe the cylinders are not firing evenly and at 180deg apart or the bike is for whatever reason running like a total bag of shaZam!, which from the video...... obviously isn't

Come on......convince me otherwise 

Well lets look at it some more. The balance shaft, cams,clutch and transmission are all being driven by the cylinders actually putting load and on the engine. I'm pretty sure at idle with the bike in neutral the wheels aren't turning LOL.  All that load on the engine at idle, plus taking into account that when one cylinder fires it has to drive the opposing cylinder through its compression stroke while driving the load already on it is enough to slow it down.
The fly wheel is certainly there to help the crank maintain speed through inertia but, it does not keep it at a constant speed especially if the cylinders aren't balanced at idle.

Lucas, cam chain shimmy is real.

My VTR Use to do the Cam Chain Shimmy.With a pair of pistons double the size of the GS, That rattle didn't sound very inviting. A set of manual ape tensioners cured that woe.. Cam Chain Shimmy. 

I can't really tell if the noise happens when riding because the noise of the engine is to loud to hear the rattle. It happens when I'm in neutral and when in gear with clutch in. I noticed it a few days before the weekend, on the weekend I did a oil change - issue remains

The rattle sounds like a bolt or something is lose.
I'll try and get another recording of it.

Quote from: crackin on January 28, 2016, 04:00:26 PM
Like i said Sledge, you can believe what you want.
I'm trying to help Jimbob, all you are doing is giving me shite.
If you are so full of knowledge, experience and skill, then please go ahead and help Jimbob with his problem.

I do believe what I want thanks, and I also believe who I want

Like many other owners, including by admission yourself, I couldn't hear a thing in the video that suggested a problem and I doubted there was anything seriously wrong, consequently I wasn't going to start `inventing` possible fault theories that might be root cause, particularly when those theories question the very laws of physics!

At the time I thought If anything the carbs might, and I say MIGHT benefit from a sync`....but I thought I had made that's clear, apologies if not.

However, now that we have some further info I am going to suggest the starter clutch could be loose on the flywheel......quite a common problem with the GS5, far more so than camchain issues...but you already knew that didn't you 



This issue has been discussed many times in this forum, search for `loose starter clutch`

I never said there was anything seriously wrong. What i said was "it maybe cam chain shimmy." I did not "invent" cam chain shimmy, maybe the engineers farcked up.
All the OP has to do is tickle the fuel screws using his or her ears as the tuning tool, and see if that cured the problem. No big deal. If it doesn't work, well nothing lost hey.
I get "cam chain shimmy" on my GS and i can tune it in and out with the fuel screws.

Quote from: 97af on January 29, 2016, 12:27:54 AM
My VTR Use to do the Cam Chain Shimmy.With a pair of pistons double the size of the GS, That rattle didn't sound very inviting. A set of manual ape tensioners cured that woe.. Cam Chain Shimmy. 

 

Tsk tsk tsk.....some people eh?

 

Crackin, maybe you need to replace your cam chain adjuster.  Maybe you need a new attitude adjuster, too.

I've never heard of cam chain noise caused by imbalanced cylinders and despite a sincere effort in searching the internet and looking through published scientific research on engines I have come up with exactly zero references to cam chain shimmy or its equivalent.  Please provide evidence. 

Obviously cam chains can make noise, that's why chain guides and tensioners exist, but I find it hard to believe that cylinder imbalance can tighten and slacken the cam chain to the degree that it makes noise despite having guides and a functioning adjuster.

If cam chain shimmy from imbalanced tuning exists why don't single-cylinder motorcycle engines suffer from it continuously.  And would this previously unknown phenomena would be half as likely to occur on a 4-cylinder engine?

You imply that there is no harm in trying out your theory but I think there is potential harm in 1 messing with fuel screws without a clear idea of a goal or method of adjustment and 2 wasting time hunting ghosts when there are a dozen common causes of "rattle" sounds.

Quote from: crackin on January 29, 2016, 07:38:12 AM
I get "cam chain shimmy" on my GS and i can tune it in and out with the fuel screws.

Cant tune out busted valves, pistons and head work with air screws when the spring in tensioner goes south...at least with the interference VTR..YMMV

For the original poster... Check your exhaust manifold bolts for tightness....Just for giggles...

Cool I'll check the pipe bolts. I don't think it's the starter clutch because I had that issue a few months ago and replaced all 3 bolts which fixed the issue and this rattle is very different to the noise that makes.