Knocking noise and Spedometer issue

[darkskies]

Hi Group, This is my first posting to the forum.
I recently purchased a year 2000 BMW F650GS with 35k miles on the clock.
The bike appears to run fine and is a pleasure to ride, however I do notice the engine does sound a bit noisy (knocking type sound) when the engine is idling at 1500rpm but quickly disappears at around 2500 rpm.
Secondly, I noticed that the speedometer rises to 15mph if I rev the engine whilst the bike is stationary.
Any suggestions or comments would be most welcome,
Rob

[PaulEngland]

Dos the knocking noise happen when you start it from cold then goes away when the bike has warmed up a bit also by increasing the revs?? this could mean cam chain tensioner is at fault, I need to change mine as it doing the same***8230; here is a link that might help Cam chain tensioner more info

Sorry cant help much on the speedo issue, I would want to plug the bike into diagnostics fault code reader to see if any fault codes come up first!

[darkskies]

Hi Paul,
The knocking noise is more noticeable when the engine has warmed up, but like I say disappears at around 2500rpm and onwards.
Regards the diagnostics fault code reader, can I buy this instrument or is it a visit to my nearest BMW service centre?
Thanks,
Rob

[The Wilbur]

The noise at 1500rpm that goes away at 2500rpm sounds like cam-chain to me. Tensioner needs looking at.

The speedometer is an electronic device. For any strange electrical effects, always start by checking that the Battery Terminals are clean & tight.

[darkskies]

Thanks, The Wilbur.
I will check the electrical connectors as well just in case there is any corrosion on the terminals.
Am I right to assume that the cam chain tensioner is a none serviceable item and would require a new replacement?
Regards,
Rob

[The Wilbur]

I've not had any dealings with the cam-chain tensioner on these bikes, but have freed the odd 'sticky' one out with a sharp tap with a hammer

Have a look through the Chain Gang FAQs, via the link at the top of the page. Loads of good reading in there.

[Ton]

If the noise goes when you rev it up it is more then likely not the cam chain teinsioner.
If you take the rocker cover off you can also see it when you look at the cam chain. If the tensioner is sticking the chain will be slack. And the chainguide will not be tight against the camchain.
If you turn over the engine by hand you will hear more noise too and the chain will not be tight around the cam sprockets or whatever you call them.

Ton

[PaulEngland]

Chain Gang FAQs (very strange noises)

Check out noise number 34 in the "Do you have a short list to guide me in the right direction?" that's listed in the link above...

[Ton]

Hi Paul

I checked this too. But there could be more causes for similar noises that is why I rather take the rocker cover off and look and feel the chain.
I have seen lots of engines with worn camchains or camchain tensioners and the noise does usually change when you rev it up and goes less but it is still there.
And when you take the rocker cover off you get the shock as you can just lift the chain of the sprockets or move the guide backwards and forwards.I was the one in the garage who always loved making the customer (not happy) as I loved chainging cam chains and gears on the Mercedes cars.
It was in fact the first thing I checked on my bike when I checked the valves. If the chain is not tight and it makes lots of noise when you turn it over by hand then usually your tensioner is seized up.
You will also find when tickover is to slow that you gets lots of noise but this is normal.

Ton

[darkskies]

Thanks guys for the helpful advice.
I will check the cam tensioner/guide and valve clearances and report my findings.
All the best
Rob