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Nasty rattle - camchain?

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Mudskipper
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Joined: 22 Aug 2006
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PostPosted: 08:38 - 14 Jul 2009    Post subject: Nasty rattle - camchain? Reply with quote
Riding to work this morning and the slabby (GSXR750G) has a worrying rattle.

It's coming from the top of the engine, rattles on idle and increases with revs rather than speed.

I did the valve clearances on Friday. The engine has always been noisy but the actual rattle was never this bad.

I am thinking it's camchain related, and it's either more noticable because the rest of the engine is less noisy (wishful thinking? Laughing ) , it's simply got worse, or I've done something to it when I was in there.

Another thing is the power delivery - it is flat, right through the rev range. Before it had flat spots, as the carbs need a service, but now it's just utter pants. So there is definitely something amiss fuelling wise too.

Maybe it's a coincedence and I just pinched a hose putting the tank back on?

Is there any problem which would display both the rattle and the flat power as symptoms?

If it's the cam chain, can I solve it without buying any spares? What kind of tensioner do the oil boilers have?

Looks like I will be going to Rock & Bike Fest in a car this weekend. Sad
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CBR125|||GSXR400|||CBR400|||CBR400|||CB250RS|||GSXR750|||CB250RS Mr. Green
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Thom
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Joined: 24 Oct 2007
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PostPosted: 09:54 - 14 Jul 2009    Post subject: Reply with quote
my divvys valve shims rattle more now that theyre within spec if that helps. also could it be possible you have shifted the cam chain 1 tooth or similar? however this would probabaly make runnign quite poor.

If it is the cam chain have you adjusted it properly?
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)
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Blue_SV650S
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Joined: 27 Nov 2008
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PostPosted: 10:32 - 14 Jul 2009    Post subject: Reply with quote
Is it shims or tappets?

if it is tappets then perhaps one of the locknuts wasn't done up correctly/worked it way loose? If you are not getting full lift, it'll be flat as a phart!! Wink

if it is shims, you would have to have disturbed the cam chain tensioner when putting cams back in. It might be sticking (try winding it in and out a few times).

Also ... and I don't want to seem rude ... but are you sure you set the gaps correctly? ... its not unheard of for people to get measurements in metric and imperial mixed up (depending on gauge and book reference) ...
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Mudskipper
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Joined: 22 Aug 2006
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PostPosted: 10:41 - 14 Jul 2009    Post subject: Reply with quote
Blue_SV650S wrote:
Is it shims or tappets?

if it is tappets then perhaps one of the locknuts wasn't done up correctly/worked it way loose? If you are not getting full lift, it'll be flat as a phart!! Wink

if it is shims, you would have to have disturbed the cam chain tensioner when putting cams back in. It might be sticking (try winding it in and out a few times).

Also ... and I don't want to seem rude ... but are you sure you set the gaps correctly? ... its not unheard of for people to get measurements in metric and imperial mixed up (depending on gauge and book reference) ...


It is tappets, I did double check every gap before I put it all back together. Guess I'll need to whip to cover off and check again! Laughing

If an error doing the tappets would result in the flatness, then the evidence points to my handywork I guess. Ah Bollocks. Laughing

Cheers for replies Thumbs Up
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CBR125|||GSXR400|||CBR400|||CBR400|||CB250RS|||GSXR750|||CB250RS Mr. Green
"You're clumsy, you eat too much and you behave like a 12 year old boy. But you know what? Every once in a while, you find a thumb."
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Blue_SV650S
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Joined: 27 Nov 2008
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PostPosted: 14:34 - 14 Jul 2009    Post subject: Reply with quote
Mudskipper wrote:


It is tappets, I did double check every gap before I put it all back together. Guess I'll need to whip to cover off and check again! Laughing

If an error doing the tappets would result in the flatness, then the evidence points to my handywork I guess. Ah Bollocks. Laughing

Cheers for replies Thumbs Up


Yep, I'd point the finger at tappets over the camchain as the camcahin tends to quieten a bit when revved ... so yep, sadly you need to go back in and a: check the correct feeler is being used and b: nothing has come undone since you last went in there!! Thumbs Up

I am thinking you might have used the wrong feeler by mistake and got the gaps a mile out ... Shifty
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Mudskipper
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Joined: 22 Aug 2006
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PostPosted: 14:49 - 14 Jul 2009    Post subject: Reply with quote
Blue_SV650S wrote:
Mudskipper wrote:


It is tappets, I did double check every gap before I put it all back together. Guess I'll need to whip to cover off and check again! Laughing

If an error doing the tappets would result in the flatness, then the evidence points to my handywork I guess. Ah Bollocks. Laughing

Cheers for replies Thumbs Up


Yep, I'd point the finger at tappets over the camchain as the camcahin tends to quieten a bit when revved ... so yep, sadly you need to go back in and a: check the correct feeler is being used and b: nothing has come undone since you last went in there!! Thumbs Up

I am thinking you might have used the wrong feeler by mistake and got the gaps a mile out ... Shifty


Feeler was correct, the concern I do have is that I bodged them up the first time.

That is, I misread Haynes and tried to check ALL the valves with the cams in the same position. Embarassed You are supposed to check half and then turn the engine to line the cam notches the opposite way, then check the other 8.

I realised this and re-did them all properly again. Then double checked them all after.

It had been a long and stressful day actually GETTING to that point though, so error on my part is not only possible, but actually fairly likely, now I think about it. Sad

I'm not gonna drop a valve riding it 3 miles back home as it is, am I?
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CBR125|||GSXR400|||CBR400|||CBR400|||CB250RS|||GSXR750|||CB250RS Mr. Green
"You're clumsy, you eat too much and you behave like a 12 year old boy. But you know what? Every once in a while, you find a thumb."
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Barry_M2
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Joined: 09 Sep 2004
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PostPosted: 15:02 - 14 Jul 2009    Post subject: Reply with quote
Mudskipper wrote:
That is, I misread Haynes and tried to check ALL the valves with the cams in the same position. Embarassed You are supposed to check half and then turn the engine to line the cam notches the opposite way, then check the other 8.

I realised this and re-did them all properly again. Then double checked them all after.

It had been a long and stressful day actually GETTING to that point though, so error on my part is not only possible, but actually fairly likely, now I think about it. Sad

I'm not gonna drop a valve riding it 3 miles back home as it is, am I?


Shocked That is quite a big mistake to make! You're clearances would have been well out!!!

If they are ok now and you have set them correctly, then you should be fine. The valves wouldn't have opened fully before, so no real damage other than the rockers giving them a reall hammering!

It'll be fine! Thumbs Up Wink
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Blue_SV650S
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Joined: 27 Nov 2008
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PostPosted: 15:14 - 14 Jul 2009    Post subject: Reply with quote
Mudskipper wrote:

I'm not gonna drop a valve riding it 3 miles back home as it is, am I?


With huge clearances - you won't drop a valve no, so that isn't a worry. Keep the revs as low as possible though.

Does sound like human error I am afraid!! Embarassed
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