Strange Engine Knocking
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- Posts: 197
- Joined: Fri Jan 25, 2013 12:33 pm
- My Bike: CBR600RR, ZXR400 L-2
- Location: Waterlooville, Hampshire
Strange Engine Knocking
Hi guys,
My top end has inherited a strange rattle/knocking sound which behaves very strangely, i'll do my best to describe it here:
Basically, when the bike has been left for a few hours, upon starting up for the first 2 seconds the rattle will be present, the second I rev it a tiny bit it stops. The bike then has all the power it should, and rides lovely. After riding for around 5 minutes and the bike is warm, the rattle then returns, and is constantly present until the bike is stopped and left to sat for a while again. Whilst riding with the rattle, when opening the throttle, the bike feels like it has no power whatsoever, and struggles climbing through the revs. The rattle is far more noticeable at higher revs, but also idle.
The cam chain was replaced at the weekend as I thought it was this, but it is still present following this.
The rattle sounds like it is coming from the top left of the top end but I am not sure.
Any ideas would be appreciated,
Jamie
My top end has inherited a strange rattle/knocking sound which behaves very strangely, i'll do my best to describe it here:
Basically, when the bike has been left for a few hours, upon starting up for the first 2 seconds the rattle will be present, the second I rev it a tiny bit it stops. The bike then has all the power it should, and rides lovely. After riding for around 5 minutes and the bike is warm, the rattle then returns, and is constantly present until the bike is stopped and left to sat for a while again. Whilst riding with the rattle, when opening the throttle, the bike feels like it has no power whatsoever, and struggles climbing through the revs. The rattle is far more noticeable at higher revs, but also idle.
The cam chain was replaced at the weekend as I thought it was this, but it is still present following this.
The rattle sounds like it is coming from the top left of the top end but I am not sure.
Any ideas would be appreciated,
Jamie
- RedexRobB
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- Location: Ipswich, Suffolk
Re: Strange Engine Knocking
My first thought was the cam chain. Get the rocker cover off and have a good look round and check the clearances. Check the cam lobes for wear too.
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- Posts: 197
- Joined: Fri Jan 25, 2013 12:33 pm
- My Bike: CBR600RR, ZXR400 L-2
- Location: Waterlooville, Hampshire
Re: Strange Engine Knocking
I thought that too,
Interestingly, before replacing the cam chain I seem to remember the noise was always present, and with the new cam chain it is now doing the whole on/off thing.
Valve clearances were only done in June, but will give them a check over,
Thanks Rob
Interestingly, before replacing the cam chain I seem to remember the noise was always present, and with the new cam chain it is now doing the whole on/off thing.
Valve clearances were only done in June, but will give them a check over,
Thanks Rob
- banner001
- Track day God
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- My Bike: ZXR400 L4
- Location: Nuneaton
Re: Strange Engine Knocking
you might want to check your rocker arms for wear as well, this can cause a tapping sound.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said
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- zxr400 oc member
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- My Bike: ZXR400-M4, ZX4, ZX6R.
- Location: Herefordshire
Re: Strange Engine Knocking
Ht lead for #1 or #2 arcing to the head/cam cover.
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- zxr400 oc member
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Re: Strange Engine Knocking
Rocker arms is a very consistent knock.. In that its just there all the time
- noelb
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Re: Strange Engine Knocking
Does it sound Internal? Check all the daft other stuff too, loose exhaust, random brackets etc. A blown exhaust gasket can sound like a weird knock as well...
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- Posts: 197
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- My Bike: CBR600RR, ZXR400 L-2
- Location: Waterlooville, Hampshire
Re: Strange Engine Knocking
Interesting point to consider, will check on this too!zimm wrote:Ht lead for #1 or #2 arcing to the head/cam cover.
- banner001
- Track day God
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Re: Strange Engine Knocking
ive had this too, couldnt find the source of the sound but it sounded top-end, i had removed the engine to get to the cams, no wear/damage on them, replaced the exhaust gaskets at the time and the sound went away...noelb wrote:A blown exhaust gasket can sound like a weird knock as well...
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said
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- Posts: 197
- Joined: Fri Jan 25, 2013 12:33 pm
- My Bike: CBR600RR, ZXR400 L-2
- Location: Waterlooville, Hampshire
Re: Strange Engine Knocking
Didn't consider this either, would this cause a large lack of performance though? I know it messes with the back pressure etc. but wouldn't have thought it would cause such a large difference.banner001 wrote:ive had this too, couldnt find the source of the sound but it sounded top-end, i had removed the engine to get to the cams, no wear/damage on them, replaced the exhaust gaskets at the time and the sound went away...noelb wrote:A blown exhaust gasket can sound like a weird knock as well...
Will get some more exhaust gaskets on eBay tonight!
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- Posts: 197
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- My Bike: CBR600RR, ZXR400 L-2
- Location: Waterlooville, Hampshire
Re: Strange Engine Knocking
Just thought I'd update the post so people know what happened...
Turned out to be a blown exhaust gasket, thanks a bunch to cargo, noelb and Banner! So happy to have my bike back sounding great, and at the cost of £4 for the new gaskets!!!!
Cheers for the help everyone
Turned out to be a blown exhaust gasket, thanks a bunch to cargo, noelb and Banner! So happy to have my bike back sounding great, and at the cost of £4 for the new gaskets!!!!
Cheers for the help everyone
Last edited by JamieNeve on Tue Oct 28, 2014 8:10 am, edited 1 time in total.
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- zxr400 oc member
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Re: Strange Engine Knocking
Thanks for posting the result - great to know the outcome and that your sorted out )
We are we're we are..
- noelb
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Re: Strange Engine Knocking
Good to hear dude!