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Discussion Starter #1 (Edited)
Hi Gents

Just a quick shout for some help if possible.

I know it's almost impossible over the net, but here it goes.

When my Babe is at running temp, she has a knock, a low dull thud, only on deceleration, is this what you guys would put as bearing knock? Or is there any other possible thing you could think of?

I'm on my 2nd engine now and before I pull this 1, I'd like some opinions.

I've read all over the web, that it isn't just a matter of replacing bearings as the rod bearings ect.. will be affected and then bolt and then rod journal "trueness" will also need to be checked :banghead. Is this true?

From experience, I would like to believe that at this point no damage would have been done to the crank, if it is a bearing, but again would like opinions.

Also, a mechi has told me that the 12 has crank counterbalance weights, that if sticky/loose, could also give the same indication.

The motor is sweet other than this, no chain noise, no rattle nothing, I've changed oil and it looked good with no metal pieces, but a slight silver shimmer in the sun. I'll cut the filter up in the morrow and look closer, but so far it looks clean, shon a torch in it, all that, so far and all good. any comments or opinions, would be most greatly appreciated.

Thanks in advance guys, Ride safe and keep the rubber on the tar.

Sorry forgot to mention, this is when the bike is in Neutral and standing still. Not riding so it cant be chain tension or sprockets. Only thing I have not checked, is pulling in the clutch and listening if there's a difference then.
 

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I can tell you what it isn't, wouldn't and shouldn't be related to; pre-ignition. It wouldn't be because closed throttle operation would reduce the air pressure to the cylinders. So unless your timing plate goes crazy and advances the timing 90 degrees during deceleration, that wouldn't be it.

Timing chains and counter-shaft balances may be at issue if their chains have stretched, which is probable given enough miles on the engine. The CCT chain could be checked to see which tooth it's on and reset to factory tension to give you an idea if it's the timing chain, but the best way to tell that is to actually measure the distance between the links, using the service manual's wear threshold.

How many miles are on this engine and do you know if it has been either run excessively under high load/low RPM/WOT or over-revved in its lifetime?
 

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Discussion Starter #4
Hi Guys, Thanks for the quick replies.

Motor has roughly 19000Km's which is roughly 12000Miles. It has been well looked after and regulary serviced and never abused.

The noise is a continual run down THUD THUD THUD as the rpm's decrease.

What did happen though is the A holes never set anything when replacing motor, and I had it overfill the oil with petrol. It never ran long like this, but it did run for a short while so am afraid this could've washed the bearings dry and hence now the knocking.

What are the possibilities of changing the bearings, both big ends and mains with out having to have the rods journals worked on and having to replace the rod bolts? Provided of course there's no damaged other than to the bearing shells.

Apologies for all the questions, but if I can get some other opinions things to try before ripping it apart, it may save me a small fortune as here in Sunny Old SA parts are defi not cheap.

Cheers again.
 

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Hi Guys, Thanks for the quick replies.

Motor has roughly 19000Km's which is roughly 12000Miles. It has been well looked after and regulary serviced and never abused.

The noise is a continual run down THUD THUD THUD as the rpm's decrease.

What did happen though is the A holes never set anything when replacing motor, and I had it overfill the oil with petrol. It never ran long like this, but it did run for a short while so am afraid this could've washed the bearings dry and hence now the knocking.

What are the possibilities of changing the bearings, both big ends and mains with out having to have the rods journals worked on and having to replace the rod bolts? Provided of course there's no damaged other than to the bearing shells.

Apologies for all the questions, but if I can get some other opinions things to try before ripping it apart, it may save me a small fortune as here in Sunny Old SA parts are defi not cheap.

Cheers again.
:headscratch:headscratch
clear this up .... what did you do??
 

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Discussion Starter #6
Slim

I drained the oilld and put new filter oil ect...

I also set the TPS voltage to correct as it was reading 0. some what DC volts. I set it to 1.16VDC this bringing it back into the correct range on the fueling for the ECU.

So far, it now aint over fueling and it made a huge improvement to the smoothness and response on the throttle.

Look I guess I'm chasing my own tail here, was keen just to get some other opinions as others may have had similar experiences and it wasn't as severe as I'm imagining. I Hope but doubt it :banghead.

Any further comments welcome. I'll see if I can get it warm and record the sound and place a clip on here. That may help :headscratch
 

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on decel a loose chain can thump, causing a surging feel and a weird thump sound.
also if sprockets and chain are worn past spec.

just looking for the easy fix here ......
Is your chain in spec and properly adjusted?
 

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Discussion Starter #8
Slim Cheers for the reply M8

Possibley thinking of adjusting the cam chain tensioner and seen if that makes a difference. Hope U got it there M8, haven't seen the actual chain or cam sprockets to check, but might just have to as thats easier than the bottom end.

The noise appears to be from the centre of the block.

Thanks again for the responses, will try and get some things done the weekend and see how it goes.


Cheers
 

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I was just going to say the same thing as Slim1100. Check the chain tension, check the links for a stiff one, and oil it.
 

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I think counterbalancer is the important part of bike having a specific type of correction i suggest you to take a tour to a garage and find out the problem.
 
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