Knocking engine sound.

KP100 · Aug 13, 2018

My bike is developing a knocking sound .

It is louder than the standard exhaust note.

It is only apparent when engine is under load. Like a slapping piston. Or the sound the engine makes when labouring from under reving. Except its everywhere in the rev range. Not as apparent with a cold engine.

It has developed over 6 months of daily commuting.

Is it the end? Someone at work suggested a small end or even a timing issue, other suggested ear plugs. :confused:

Santa-2512 · Aug 13, 2018

Start with some basics

What model

What year

Milage

Service history

When was the last service - very important

When were the valves & endgloat last set / checked ( this makes a big difference)

Then look at some detailed stuff

Doe it make the niose from cold ? or only when warm.

Is the bike started on the side stand ?

does the noise increase / decrease ? with increased RPM

Is it one side or the other?

Does the noise increase / decrease if you pull the clutch in?

If poss get a vid linked with the noise ..

There have been a few recently on here with knocking noises - high temps and suspect oil dont help

Deleted account 190920001 · Aug 13, 2018

Try tightening the exhaust port joint. Many an engine has been written off until they were tightened.

Pukmeister · Aug 13, 2018

Change the oil and filter, noisy when hot is usually when the oil is too thin from use. Fresh oil sorts it, ideally 20W50.

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Mac One · Aug 13, 2018

If it's a GSA, check the crash bars aren't loose and check the back of the auxiliary lights aren't knocking against the upper crash bars. :thumb2

GSGRIFF · Aug 13, 2018

Hey santa is it bad starting the bike on it's sidestand? This is what I normally do...

Santa-2512 · Aug 13, 2018

GSGRIFF said:
Hey santa is it bad starting the bike on it's sidestand? This is what I normally do...

No its ok to start on the side stand, but you may hear it knock a bit longer as it takes sometime for the RH cam chain tensioner to build pressure.

My bike was clattering and knocking quite badly on the RH side, with the help of a fellow member, we reset the valve timing and endfloat and drained the oil.

It looked quite thin & watery, and had more than expected colours in the oil. ( We think its been worked for some time and was breaking down)

We refilled with 10W/40 and are in the process of running for 1K and then are going to redrain the oil / filter & refill with 20W/50

There was a vast improvement in noise levels simply by putting fresh oil in & resetting valve & endfloat clearances

If you do a search under poor running, there is a video i posted, so you can hear the noises i had

KP100 · Aug 14, 2018

Thanks for the ideas. Its a 2004 1200 GS.

I have had it from 30k now at 50k service history from the previous owner not BMW but was backed up with receipts.

I use 10/40 in it. Every 7k With quality semi.

I start it while on it and drive off within the time it take to put my gloves on.

The loose exhaust bolt has me thinking. Thats exactly what it sounds like. Like a leak. But I could not see any evidence . I did have it off last year for cleaning but torqued them as listed in the book. Will recheck first thing. Do the gaskets require replacement?

The noise gets worse as the engine heats and is not clutch/gearbox related. They have a rattle all of their own that also needs addressed at some stage.

I did the valve clearances about 15k ago. They did not require much adjustment. I thinks its a little to loud to be a clearance issue.

I also have Aux lights. thanks. I will check and get back.

Mistacat · Aug 14, 2018

As you say that the noise is under load, have you considered checking the Knock sensors with a GS911.
If the Knock sensors are not working try high octane fuel to see if it improves.

Slipperyeel · Aug 14, 2018

KP100 said:
The loose exhaust bolt has me thinking. Thats exactly what it sounds like. Like a leak. But I could not see any evidence . I did have it off last year for cleaning but .....Do the gaskets require replacement?

I wouldn't imagine a leaking exhaust flange to sound like 'knocking'. Perhaps more of a ticking.

But ref changing the exhaust flange gaskets. I'd have said yes, 100% of the time...

Santa's comments ref balancing and oil change etc. sound like sensible starting points.

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Santa-2512 · Aug 14, 2018

I changed the oil again today.

from 10W/40 to 20W/50

Noticibly quieter once the tensioner had filled.

gearbox aside, it's almost comparible to a jap 4 noise wise now

Slipperyeel · Aug 14, 2018

Santa-2512 said:
I changed the oil again today.

from 10W/40 to 20W/50

Noticibly quieter once the tensioner had filled.

gearbox aside, it's almost comparible to a jap 4 noise wise now

I put in 20/50 fully synth before I left for this trip. Partly because of the heat I was anticipating. I agree, it's made it noticeably quieter! But to be honest, after the 1150, I thought it was already very quiet, so I was a little surprised!

It seemed to take a while to get into the tensioners, I mean almost a couple of minutes. Might change it if we have a cold winter...

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Santa-2512 · Aug 14, 2018

Slipperyeel said:
I put in 20/50 fully synth before I left for this trip. Partly because of the heat I was anticipating. I agree, it's made it noticeably quieter! But to be honest, after the 1150, I thought it was already very quiet, so I was a little surprised!

It seemed to take a while to get into the tensioners, I mean almost a couple of minutes. Might change it if we have a cold winter...

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Castrol do a 10W/50 best of both worlds

Could we use it??

Slipperyeel · Aug 14, 2018

Santa-2512 said:
Castrol do a 10W/50 best of both worlds

Could we use it??

Haven't seen that. But yes, sounds ideal!

Where do we get it? !

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Pukmeister · Aug 14, 2018

Last time I bought some Castrol Power 1 Racing 10W50 I got it from www.moto-oil.co.uk in Poole.

Their website may be down as they were recently victims of unwanted web links to gambling sites etc and they are trying to get it fixed and back up.

Opie oils probably sell it as well, plus other brands like Motul etc.

Santa-2512 · Aug 14, 2018

Opie oils only do it in 1L bottles

Its a synthetic oil - not mineral btw

You can get 4L quantitys in Motul or other brands - not cheap mind

They also do 10W/60 - which i believe Guzzi's use

KP100 · Aug 15, 2018

Its hard to describe a sound , but it does sound like a knocking. I tightened the bolts on the exhaust a little. Dam scarry . last thing want it a bike that was running going to the shop for a broken stud.

Also tightened one very lose Aux light on the crash bars.

Not got a chance to test it yet, but I still suspect its not that simple. It never is.

Next is oil and filter. Has to be ordered.

Mac One · Aug 19, 2018

KP100 said:
Its hard to describe a sound , but it does sound like a knocking. I tightened the bolts on the exhaust a little. Dam scarry . last thing want it a bike that was running going to the shop for a broken stud.

Also tightened one very lose Aux light on the crash bars.

Not got a chance to test it yet, but I still suspect its not that simple. It never is.

Next is oil and filter. Has to be ordered.

Have you found the source of the knocking yet?

Mac One · Aug 23, 2018

Mac One said:
Have you found the source of the knocking yet?

Bin Ridin · Aug 24, 2018

You can get a good rattle from the windscreen if a bit loose on the pivot pins above the headlight. I put o-rings on them to take out the play due to wear.

Knocking engine sound.

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