Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.

1996 PC26 nasty rattle sound

Share
avatar
marijn38
Newbie
Newbie

Posts : 3

1996 PC26 nasty rattle sound

Post by marijn38 on Wed 31 Oct 2018, 8:37 am

Good day to you all and thanks for having me!
I hope I'm posting this in the right category if not then I'm sorry.

I thought maybe someone on here could point me in the right direction.
Until recently my old cb500 was running just fine, but not too long ago it developed a nasty rattle inside of the engine block.
It sounds cyclic as in the rattle comes around with the revolutions of the engine block.
It doesn't matter if I engage the gear or clutch, that changes absolutely nothing.
It is a PC26 1996 with 40.4k miles on it. The camshaft chain and tensioner have been replaced (workshop/garage) last year and have since then performed fine for at least 6k miles.
Since the whole camshaft-chain operation cost me quite a bit of money i decided to have a look with my uncle who has been working on motorcycles for whole his life. 
So we started by rotating the engine by hand but it revolves perfectly no sounds to be heard. Then we removed the tank, cooling and engine head. revolved it on the starter and nothing to be heard.
Checked all valve clearances against haynes manual (twice). All perfect within margins and no damage to be seen. Same goes for oil, coolant and sparkplugs everything looks just fine.
Then we set to take of the clutch housing and clutch itself. Although I'm still not shure if the oilpump chain behind the clutch is supposed to be that loose (haynes says nothing about this).
But I do not think this is the cause of the sound. So what am I trying to achieve by this post one might ask. Maybe anyone recognizes the sound or might have a clue where it is originating from.
I'd like to have at least a general direction where to look before taking the whole bike apart. So if you have got anything for me please let me know! Or if you just want to laugh at me for having such
a shitty sounding bike that is fine by me as well. Wink I have put a small videoclip on YouTube with the engine sound (recorded with phone 1 meter from block in stationary) and the play on the oilpump-chain.



Anyways, I thank you for your time. Greetings from NL

Marijn V
avatar
ANDYC
the 900
the 900

Mechanic
Posts : 1025
Location : Windsor

Re: 1996 PC26 nasty rattle sound

Post by ANDYC on Wed 31 Oct 2018, 10:16 pm

Hi Marijn,
The oil pump chain is quite normal to be that loose.
I couldn't tell exactly by your video clip what the rattle was coming from.
Are your exhaust joints all tight?
It may have just been because it was running indoors that it sounded like a blowing exhaust.
avatar
eternally_troubled
Admin
Admin

Awesome!
Posts : 4001
Location : 'ere be fens. (near Cambridge)

Re: 1996 PC26 nasty rattle sound

Post by eternally_troubled on Wed 31 Oct 2018, 10:24 pm

I don't know what that noise is, but it is quite difficult to tell (in my experience) from recordings, however well they are made, unless the noise is really obvious.  Might be worth posting a clip that is a bit longer with some different engine speeds, just in case someone else can hear something I can't.

Are you absolutely sure there aren't any loose bits of exhaust (or things rubbing on the exhaust) that could make that noise?  It sounds a bit like something jangling around.

EDIT:  we both posted at the same time!  Doh...
avatar
marijn38
Newbie
Newbie

Posts : 3

Re: 1996 PC26 nasty rattle sound

Post by marijn38 on Sat 03 Nov 2018, 10:00 am

Hello,

@AndyC  Good to hear that the oil pump chain is normal like this. 
Well it doesn't have to be on time like a valve or anything so it wouldn't matter as much i suppose.
And I just realized how misleading my editing on the youtube video was. It was recorded on my phone outside and i edited the picture in later. So the sound is not recorded inside but it sure looks like it. My mistake!


@Eternally_troubled I totally agree that different engine speeds make the easier to place although that would be a pain in the ass right now since she's already taken apart quite far. This was what i had and i thought maybe a common problem or a familiar sound. Allways worth the shot right?


But I did however replace the exhaust to a stainless steel one in the spring. The old one had a leaky collector and apparently the standard pipes are quite known for being rusty. I recall the pipe was installed smooth and without a hitch (new gaskets/sealant). But I'll go double check and try to get some pressure in the pipe to see if if it is leaking anywhere. Next week i'll also be looking around with a little endoscope/borescope camera thing. Could borrow it of a friend of mine and having a little peak around on the inside sounded like a swell idea.

Sorry for the late reply it has been a hell of a week. I wish you all a very nice weekend.
Thank you, M
avatar
Oafski
Rossi
Rossi

Posts : 50
Location : Waltham Cross

Re: 1996 PC26 nasty rattle sound

Post by Oafski on Sun 11 Nov 2018, 1:00 pm

Only just spotted this but had a similar problem with my 97 model about 5 months after fitting a full Delkevic Stainless steel system. Bike sounded like a Dry Clutch Ducati and we eventually suspected the downpipes. Delkevic replaced the downpipes and that solved the problem but looking down the pipes from the silencer end there is a plate just to the rear of the "y" which on the new pipes was vertical so it looked as if the flow from the pipes passed either side of it while on the old pipes this plate would have been at 2 and 8 if viewed as at a clock face and would possibly have disturbed the flow and been rattled about by it. Might be worth a look.
avatar
marijn38
Newbie
Newbie

Posts : 3

Re: 1996 PC26 nasty rattle sound

Post by marijn38 on Sat 17 Nov 2018, 10:05 am

Yes!! It was the exhaust, you guys were right.
Went to check the bolts that hold in the down pipes and i could turn them by hand.  tongue
How very stupid that i didn't check that earlier.
Well I have learned a lot in the progress and I must say she looks brand new on the inside.
Parts are on the way and then i'll give here some maintenance and we should be good to go.
I'd love to buy you guys a beer but according to the flags next to your names neither of you are close.
Anyways I wish you all a great weekend and thanks again,

Best regards, Marijn
avatar
ANDYC
the 900
the 900

Mechanic
Posts : 1025
Location : Windsor

Re: 1996 PC26 nasty rattle sound

Post by ANDYC on Sat 17 Nov 2018, 11:20 am

Glad you managed to sort it Very Happy
avatar
eternally_troubled
Admin
Admin

Awesome!
Posts : 4001
Location : 'ere be fens. (near Cambridge)

Re: 1996 PC26 nasty rattle sound

Post by eternally_troubled on Sat 17 Nov 2018, 7:29 pm

@marijn38 wrote:
I'd love to buy you guys a beer but according to the flags next to your names neither of you are close.
Anyways I wish you all a great weekend and thanks again,

Best regards, Marijn

Glad to hear you got it fixed; have a beer 'for us' to celebrate! :)

Sponsored content

Re: 1996 PC26 nasty rattle sound

Post by Sponsored content


    Current date/time is Mon 21 Jan 2019, 9:48 am