GPZ 500s rattle/knocking?

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

Ok my GPZ500s 97 (ex500 d1) has got a rattle/knock coming from the top end, at tickover its not as noticable but still there, it gets louder/quicker up to around 3-4k rpm then seems to stay constant throughout the rest of the rev range, although its hard to tell as by around 5k rpm the exhaust noise covers it. I cant tell if theres any loss in performance as i bought it like this, but its fast and will just about squeeze 120mph indicated....Im almost certain theres no performance loss (other than the lack of backpressure due to hole in exhaust)

Its done 20k miles (apparently)

My first thought was the tappets, which il be re-setting this weekend, and then balancing the carbs. however i then started thinking it could be the cam chain, but at 20k id be surprised, even the tensioner, any thoughts on this by someone experianced in them?

Also, i noticed yesterday one of my exhaust headers has a hole in it, as does the exhaust balance pipe, so iv got a nexxus 2-1 hopefully arriving and being fitted tommorow, im just wondering if this could be anything to do with the noise, as occasionally it will backfire which cant be good for the clearances, if the valve clearances are well out how bad can it sound?

Im hopeing after all of that the noise will be gone, surely if the noise was something worse like a broken valve spring/piston ring there would be a loss in performance?

Absolutely anything youve got to say about all of the above would be very helpfull, cheers Thumbs Up

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''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Ok. It's an inherantly rattly engine to start with.

I never worked out where mine was coming from but I suspect it's primary drive noise.

Balancing the carbs usually quietens them down a lot.

Not having a hole in your exhaust will probably work wonders too.

With the hole, I bet it's doing a bit of popping and banging on the overrun too.

Shouldn't be the camchain at 20k miles.
Balance the carbs, fix the exhaust and see how it goes.

If you want to check the tappets, you will need two new o-rings for the coolant pipes that go through the rocker cover. If you attempt to re-use the old ones it WILL leak coolant into the sparkplug recess and pish it out through a small hole in the side of the cylinder head. They cost about a quid from kawasaki.

EDIT: Fix the exhaust first, then balance it.
____________________
“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.

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

Thanks very helpful, put my mind at rest a little. Hadnt thought about the o-rings either, just picked up a couple for 80p Thumbs Up

Il let you know how it sounds after the weekend. Karma

____________________
''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Oh yeah. If you're fitting a motad 2-1, you need to add a spacer in the form of 2 or 3 thickish washers between the bottom right belly pan bracket and the belly pan itself. Also an idea to bend both bottom brackets to the right slightly.

This makes the belly pan stand away from the exhaust a bit further. If you don't, it can melt a hole in the belly pan.

Some people also stick some metal tape/foil to the inside of the belly pan next to the pipe for the same reason..
____________________
“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.

flumpy7 · Could Be A Chat Bot Joined: 31 May 2008 Karma :

Im no mechanic but i've had a few of these and they all rattle from the top end. As already suggested gettin carbs balanced seems to make it less obvious but the engines generally sound pretty rough. They are truly bullet proof though and easily see off any other 500 twin on the market and even keep up with a few 600's. Twisted Evil

I recommend the motad, i notcied no performance loss but it would be worth doing the carbs after fitting it. Long live the GPZ!

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

Right slight problem, iv been doing the clearances this morning and when i line the t-mark on the rotor up with the timing slot on the casing, the left cylinder cam lobes arent pointing up, there pointing down, and when i spin it round to the t-mark the second time, the motor wont hold with the t-mark lined up, it almost lines up and then the motor spins itself so i lose it? is this normal? When the c-mark is lined up the right cylinder lobes point up as they should? shall i just do the clearances with the lobes as straight up as possible?

Also im not very confident on judging the drag from the feeler guage, should there be hardly any drag at all?

Cheers anyone
____________________
''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

OK when the left cylinder cam lobes are pointing up and the t-mark is lined up, i have to hold the engine in that position or it will spin round more, but it should stay in position shouldnt it?

EDIT: also, the slots on the right-hand side of each camshaft point the same way, rather than towards or away from each other?
____________________
''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

Right its all back together now, the exhaust didnt arrive so il have to do that and the carbs on monday (got the week off Dance!

)
Did the tappets though, some where a little loose, the engine noise has quietened down very slightly not that noticable though, the rattle's still there....have to wait till monday.

Edit: Oh and just so i know, iv lost one of the tubes off my carb balancer, do they both just have to be identical, and do they need the little valves on them? because as far as i remember they were just to adjust the sensitivity, and obviously i only now have 1 so cant use it?
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''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Sorry. I've been out working on bikes myself or I'd have replied.

It's turning itself because the compression is going over TDC. If you removed the plugs, it wouldn't do this.

Your initial problem was that you were 360 degrees out but you seem to have sorted this.

I just used to turn mine so the tappet I was adjusting wasn't being loaded by the cam lobe. Being bang on the timing point isn't all that critical.

If you're struggling to judge the grip on feeler guages in future, check that the maximum allowable one doesn't fit at all.

The balancer will probably bounce about all over the place without the little valve.

I have used simple rubber fuel line on my balancer before, I used a small jubilee clip to 'pinch' it in place of the valve. Bending the fuel line into a U-shape and sliding a circle of wire (round both legs of the U) towards the bottom of the U (gradually kinking the hose) also works in place of a damping valve.
____________________
“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.

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

https://i70.photobucket.com/albums/i92/shaunpearmain/28-07-08_2005.jpg
Got me exhaust today, quite chuffed with it really Thumbs Up

rides so much better with no holes Embarassed

the rattle is less noticable now, although i didnt get round to balancing the carbs il be on that tommorow morning, ordering a new CCT aswell for peace of mind.

You should have seen my face when i opened the box Laughing

i thought it had a massive dent in it, rang up motad gave them a right mouthfull they told me to ring gear4bikes (who i ordered it though) so i did and they told me its meant to be like that for clearance Embarassed

he then went on to say how many angry people give him a mouthfull Laughing

Oh and by the way, anyone know where you can get hold of a single seat cowl for one of these?
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''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''

Purplepill · Trackday Trickster Joined: 05 Jun 2007 Karma :

Balanced the carbs today, they were a little out but not much, and the rattle is still quite noticable Sad

If the new CCT doesnt quieten it down, il put it down to 'if it aint broke, dont fix it' every 4-stroke in my sig has made this noise or a variation of this noise Laughing

and the CBR is the only one that fecked up.

I tryed gettin you a vid of it running stinkwheel but my phone vid quality was so shocking you wouldnt of been able to tell anything from it Sad

____________________
''He had the confidence of a baby-goat dared to tickle a t-rex's nutsack''