GPZ500S Problem

iCraig · World Chat Champion Joined: 05 Jun 2004 Karma :

Well as some of you may know I own a GPZ500S A6, and have done 3000 miles on it since I bought it.

It recently had a new downpipe after the old one split at the link pipe underneath.

Since then I have been hearing a tappetty noise coming from the engine, I assumed it was down to the new downpipe probably being clean and not having any sort of coke in it at all. But recently the tappetty noise has started too turn into a sort of clattering noise when I take the bike off the choke in the mornings, it stops as soon as the engine is warm?

So does anyone maybe have an inkling to what it may be?

TAI,

Craig.

Git · Brolly Dolly Joined: 17 Dec 2003 Karma :

At a guess valve clearances?
When the engine is cold the gaps are slightly larger causing the tapping noise.
When the engine is warm the clearance gets smaller thus reducing the amount of tapping that can be heard.

mr.z · World Chat Champion Joined: 04 Feb 2004 Karma :

Maybe the camchain needs attention? try reving the bike and leting off sharply (while its still) any clunky noises should be investigated...

Or it could be your tappets/valves Razz

Did you change the bush with the downpipe? refiting the old one will leave a tiny gap which could be doing strange things to your fueling.. however when its warm the pipe expands that ittle bit to close the gap... dunno just a thought...

Another thing, have you checked you oil recently? amazeing how much difference there is from min to max oil in terms of noise...
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Could be 101 things, and the suggestions above are both quite likely. Also worth checking if the carbs are balanced, as if they are out then they can make the engine sound very rattly. If they were balanced with a blowing exhaust then they will be out.

The GPZ engine is quite often rattly, both from the cam chain and from the primary drive chain.

All the best

Keith
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stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

I would suggest a tiny gas leak at the header pipe where it bolts onto the engine. You may be able to hear this if you squat down next to the bike and blip the throttle, or you may feel a jet of exhaust gas blowing out if you put your hand near (careful, hot!) although it can be a very small leak.

The compression gasket under the header needs tightening down after about 100miles post-fitting because, as the name suggests, it compresses. If you didn't fit a new gasket washer, it will almost certainly not seal properly. The copper in the gasket expands through heat and so seals better as it gets warm.

I would tighten up the nuts at the header (carefully, you DO NOT want to shear them) and if that doesn't work, replace the gasket.

Mine is doing exactly the same thing at the moment, a genuine Kawasaki copper compression washer costs three quid.
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iCraig · World Chat Champion Joined: 05 Jun 2004 Karma :

Well guys I have the bike booked in for a service, and they are going to do the valves for me at the same time too.

But I have just taken a video of the bike with sound and the engine is doing said sound the video too.

Tell me what you think you can hear.

https://homepage.mac.com/craiggiles2/GPZ.MOV

You'll need Quicktime installed to play it.

TheShaggyDA · Repost Police Joined: 14 Jun 2004 Karma :

The leaky header pipe gets my vote too. Same thing happened on my GPZ1000RX.
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iCraig · World Chat Champion Joined: 05 Jun 2004 Karma :

For those who can't play the MOV file above, I have created a 324k WAV file.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Try the stuff I PMed you about, but rereading your original post, a leaky header gasket is still your best bet. It is very suspicious that it is making this noise shortly after replacing the header pipe.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Guest · Brolly Dolly Joined: 22 Apr 2004 Karma :

Nice idea posting a movie Thumbs Up

Does sound like the down-pipe blowing, did whoever fitted it use new gaskets?

iCraig · World Chat Champion Joined: 05 Jun 2004 Karma :

Well I decided to abit of bolt tightening on the downpipe that was replaced.

Since tightening it up, its quietened down a tad, and sounds like a normal parallel twin should, though the engine is reletively warm still.

I am still going to have the valves checked out mid-week, anyone know of a ballpark figure of how much it will cost and how long it'd take as I know the coolant has to be dropped etc.

And I have no idea if the exhaust gaskets were changed when it had a new downpipe as it was done by Sale Yamaha the dealer who sold me the bike, I also think they may have fitted a pipe from the D Series GPZ, does anyone know if they differ at all?

Regards, Craig.