K1100 engine knock - finally cured it!

[gladstone]

Hi,

So I replaced the alternator rubber bushes, remounted the exhaust and tightened all the bolts, adjusted the valve clearances, and replaced the cam chain tensioner. All made small improvements (at least I've convinced myself they did) but the knock was still there at idle not only when cold but recently also when hot.

I thought I'd balance the injectors but couldn't get number 2 anywhere near the mark. So I thought I'd check the clamps on the inlet rubber but slipped and hit the rubber - which stopped the knock when I pressed it! Turned out number 2 inlet rubber was split halfway around, and the rest weren't far behind. I've now replaced all the rubbers, cleaned the injectors, and changed a split breather hose and all is well.

The bike runs beautifully and has lost a lot of the 'buzz' above 5000 revs. It also idles perfectly and now pulls from tick-over in 5th gear.

Thanks for the all the advice on this site - the photo thread covering the inlet rubber replacement was invaluable.

Useful things I learnt:

- you don't have to remove the cylinder head or crankshaft covers to take off the cam chain cover, just loosen them
- put the rubber parts in hot water before fitting (esp the injector o-rings)
- remove the airbox to get to back of the inlets; makes installation easier
- to have a go! I dreaded anything involving the cams and valves and it was quite straightforward (again, thanks to this site)

Cheers

[Scott_]

So with your cam chain, did you just replace the spring loaded/pressure piston assy, or did you replace the plastic rail guide, or both?
I've got mine apart at the moment, have a new chain, and all the plastic guide parts, but have been debating about the oil pressure driven piston assy.
The oil passages are clear and it doesn't show any wear(as compared to the plastic guide parts).

[The Mighty Gryphon]

Good to hear you found your problem.  May I ask, how was the idle when the engine had the knock?  Were there any running issues like stumbling, etc.?

I have a '94 K75RT that has a loud ticking that come from the area of the alternator and starter that only appears between about 1200 and 2000rpm.  I have done all the things you mentioned, the balance on the throttle bodies is fine, but the noise persists hot or cold, in gear or neutral, with or without load.  Outside of the noise, the engine runs great with smooth idle, good throttle response, and lots of acceleration. 

It's annoying to me because I think an engine as good as this shouldn't be making these noises.

 

[Scott_]

I have a '94 K75RT that has a loud ticking that come from the area of the alternator and starter that only appears between about 1200 and 2000rpm.

Read here:
http://forums.bmwmoa.org/showthread.php?44757-K75-Engine-output-shaft-noise

I think this will help

[The Mighty Gryphon]

That sounds like my noise.  Bike has 63,000miles.

So it's a spring that tensions the "anti-rattle" gear that let's the gear rattle at low rpm?  You gotta love German engineering.  Doesn't seem like it's going to hurt anything, just makes an otherwise great bike sound like it's got stuff rolling around inside of it.

Maybe next winter...

[Scott_]

As Johnny would say, keep the throttle whacked full open then no noise to worry about--- or hear....  :2thumbup:

[johnny]

not necessarily full open... butts on the red line for sure...

j o

[The Mighty Gryphon]

Sir, Yes Sir!  Redline it is.

[gladstone]

I just replaced the tensioner. The guide looked fine (not that I'm an expert in recognising 'fine' but it looked ok). It was a lot easier than I thought it would be once I'd tie wrapped the sprockets to the chain.

The idle has dropped slightly it now sits at around 1000 on the dial. If you remove one of the rubber covers on the balance vents the revs increase - I guess that's what was happening all the time with the leak.

With the buzz I used to get above 5000 rpm I never used to rev it that much over 4500 but I was hitting the redline yesterday.

[sj2000]

Wondering if the engine ticking noise like this?