Calling all engine ears ...GPZ500S knocking :( FIXED :)

[DaveH]

Just got my self a wee GPZ500S at the weekend there.

Its standard apart from Nexxus exhaust and K&Ns, although it has not been rejetted.

Its increasingly starting to make a knocking noise is it

a) running lean and is 'knocking'
b) little end? Seriously hope not
c) A little spanish mouse is trapped and givung the castanets lalldy
d) Previously owned by Captian Hook, and nobody told the crocodile?

Recorded it and you can hear the light knocking above the engine quite well....

Anyone any idea?

Thanks in advance

Dave

[finpos]

That sounds towards the not good end of the spectrum

If by a) you mean pinking, pretty unlikely. It would be doing it mostly under load.

Before you panic about bearings etc, check out to see if the exhaust is blowing, it can sometimes make a mechanical sounding noise if it goes right where it connects onto the engine.

Sounds a bit like the bearings, though. Don't suppose you noticed if it was full of gearbox (as opposed to engine) oil when you got it??

finpos.

[DaveH]

Nope, only checked that there was oil in it, was down for changing it this weekend...

If it is the exhaust will it be noticbly louder at the front, or not too easy to distinquish if it is piston based, or will it be possible to feel the leak?

Thanks

Dave

[finpos]

Personally, I find it almost impossible to figure out exactly where engine noises come from. Best to try and feel for an exhaust leak, don't burn yourself

You can also try to quickly bung up the end of the exhaust with your boot. The engine will quickly bog down if there is no leak anywhere.

finpos.

[Retro-Man]

difficult from that sound clip, but my initial thoughts are if your lucky a very bad misfire (like HT leads on wrong way round) or a head/sump off annd inspect.

Assuming it's not a major misfire I'd start by removing the sump (presuming it has one) and removing the end caps, it does sound a little bit like big end shells.
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[DaveH]

Just been out to the bike; (ok several times trying to get a decentish recording)

Started it up and shoved my hand over the end of the exhaust to make sure I could get as gas tight a seal as possible.

Engine does change note a bit and there is a pronounced scuffling sort of noise from the front of the bike, but the engine didn't die. Tried reving slightly it and it did a bit, but nearly stalled when returning to idle.

The noise was not as obvious as before, but the engine had cooled down.

Also, during the longer recording, when gradually covering the exhaust, the noise seemed to transfer from the tapping to the scuffling type of noise, but was probably just the sound of hope sprining eternal!

Probably all pretty inconclusive until I can get time to take exhaust off and reattach.

On another note, why would someone put geerbox oil in? Was this a literal question and is it some sort of bodge to disguise this sirt if thing?

Cheers

[stinkwheel]

Right, you do get a certain amount of clattering off those engines as normal.

Yours sounds a fair bit more clattery than mine do though.

I'm not sure exactly what causes it, I suspect it is something to do with either the water pump or the primary chain.

First eliminate everything obvious such as (as mentioned) leaky headers/exhaust. (it would usually pop-pop-pop on the overrun if this was the case).

Have a listen to the engine using a sounding rod. A short length of broom handle or a screwdriver works for this. Press the rounded end firmly against your ear and press the other end against various parts of the engine. This can help to isolate where the noise is coming from. So eg, rocker cover = tappets/valve gear; barrel = Pistons/small ends/camchain; Left side = Alternator; Right side = clutch/transmission.

Listen for the camchain whirring and the tappets clicking (normal).

The noise on mine (which I now deem to be normal since it was present on all three 500 twin engined bikes I have owned, one of which only had 6k miles on) is loudest over the water pump cover on the right hand side.

This being the case, as a first off I would get the carbs balanced. This seems to quieten them right down.

EDIT: Also seems fairly sluggish off the throttle, which could again point to a balancing issue.

[DaveH]

It pops and bangs like a good un on the overrun, had put it down to the k&ns screwing up the carburation. Should get a standard airbox through the post tomorrow or the day after and will fit it and balance the carbs then...looks like a busy weekend.

[finpos]

Cynical me, but worn bearings + thick gearbox oil = sounds ok for 100 miles until the oil breaks down.

If the exhaust was properly sealed up, it wouldn't run for 30 secs, so definitely worth having a hunt around for a leak.

As Stinkwheel says, I think you can expect a certain amount of clatter with big singles/twins, so it's just the "getting worse quickly" aspect to worry about.

finpos.

[DaveH]

[stinkwheel]

Oh shit. You have it on K&N pod filters? Not a proper K&N filter in the airbox.

Get an airbox on the bugger. Kawasaki spend around 2/3 of their R&D budget on carburettion and employ accoustic engineers to design their airboxes.

As I have been finding on my KLE/GPZ hybrid, the airbox shape and size is utterly critical to the correct running of your bike. If it has pod filters on and no carburettion work done, it will undoubtedly run like a total bagowank. I'm surprised the engine revs at all above 7,000rpm.

EDIT: It will be running lean as hell.

[DaveH]

[DaveH]

[DaveH]

BTW, will the lean running damage it? Just filled it up today and its gettign 57mpg, hoping that's a good sign as for half the motorway/town distance travelled it is two up...

[hmmmnz]

you'll need the original main jets as well, get them from wemoto.
(i gather that he did change the jets when the pods were put on )
check the needle clip position and the slides while your at it.
good luck
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[stinkwheel]

[DaveH]

[finpos]

Interesting if the exhaust has been fitted recently. Remember the old adage:

"He who thinks pods are a good idea rarely bothers his arse to use new exhaust gasket"



finpos.

[DaveH]

[hmmmnz]

it would have been running like a dog with pods and no rejet, i would check just incase they have been changed out.
keep us updated
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[DaveH]

Will do, though it will be the weekend before I can get sometime to work on it

[Walloper]

Rule of thumbs:

Buy a new oil filter.

Remove existing oil filter.

Carefully cut the oil filter open.

Remove the paper and open ouit like an accordian bellows.

Look for shinny wee flakes of white-ish-grey-ish-maybe-blue-ish metal particals.

If you find them Panic a bit.

Remove sump check main and connecting rod bearings etc.

NOTE-
The hacksawing technique will introduce some metalic particals into the filter paper but they will gather near the top if you cut canny.

I will light a candle and say two/three hail Marys for you.

Good luck.
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[DaveH]

Just fitted the new exhaust gaskets....how tight do I put the exhaust nuts? Haynes doesn't give a torque for it, or a rule fo thumb either.

Can anyone tell me hpw to tighten them up correctly?

Thanks

[hmmmnz]

it should be 1.2 in the haynes manual 9-12 Nm
thats about the same resistance as an 8 year old holding the door handle from the other side and you trying to turn the handle, not a very good analogy but you get the idea,
tight but not any real weight on it just a bit more than hand tight
last thing you want to do is thread the inside of the engine,
good luck
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[DaveH]

Bike is fixed

Changed the exhaust gaskets, put in the coolant and fitted an orginal airbox. Decided to just use the petrol in the carbs to see if the noise had gone...glad I did!!

The noise was still there and was starting to despair, when I notice the right had spark plug bobbling along in time to the knocking...it was quite loose!

Killed the engine, took the plug out...dreading a stripped thread in the head, but everything seemed fine. Spark plug was in good nick, plug well was clear, so fitted it and it tightened properly, check the other one, likewise ok..so...fired her up.....

Was a sweet sounding little bike she is (even though she's two cylinders down )

Oil and filter then changed, and btw motad, gonny no obstruct the sump plug with the down pipes!!!!!! Had to slacken off the exhaust again, but luckily hadn't really put them that tight in the first place.

All that's left to do now is put the air filter back in, once cleaned, balance the carbs and put the rest of the bodywork back on...dying to take it for a blast but have got the kids this weekend, so will have to wait to Monday


Chuffed to bits that the bike isn't burst and is sounding very happy and even better than before, am guessing that's down to the airbox, gaskets and oil; makes the 4 hours it took doing this...including dodging rain....very, very worthwhile.

Thanks for all the help guys