Low rpm knock

[ME 109]

I didn't mean for you to ride it that way, just listen to it while revving it in neutral, with a rag lightly scrunched up over the hole.
A big end knock will remain audible over the cacophony of normal noises.
A breather induced knocking noise (if that's what you have) will disappear.

I wasn't riding it.
I'll try it with a rag today after work.

[ME 109]

Went for a squirt this arv with new oil, it's quieter but the jury is still out.
A knock is a knock.
It was harder to produce the knock after I got back today. There is also reasonable vale train ? clatter when revving and holding at 2500 in neutral.
Clearances are OK, End play OK,
The motor is noisier than it has been............

No sparklies in the oil is a good sign tho'

Am I a boxerchondriac?

[gspd]

There is also reasonable vale train ? clatter when revving and holding at 2500 in neutral.
The motor is noisier than it has been............

For test purposes close up the valve clearances to zero to eliminate valvetrain noises.
Tighten them up until you feel a slight resistance when spinning the pushrod and back off just a hair.

It won't do any harm just to try it that way for a few miles.

[chasbmw]

worm timing chains do produce strange noises from the centre of the engine!

[ME 109]

I put a new timing chain in the bike about 6 months ago. No improvement.

I've been running about .1mm for inlet and exhaust, but I'll try .0mm. (for a test)

Thanks.

[grant81rs]

Jeff a "boxerchondriac" not even slightly and certainly not a "hypochondrioxer", mate ya just a bloke keeping is pride & joy in order and cheers to you for being like that....

I love this sort of thread, following the progress of hunting for a mystery sound or problem and with GSPD onboard troubleshooting it will get sorted rather quickly, loving the options and suggestions in looking for the problem from GSPD and yet again all quite simple things to try "metalic oil colour when hot "etc, ya just have to know what and where to look...

Cheers to you both, Jeff for having the ears to pick up the slightest knock, normally his eyes can pick out the best knockers and GSPD for having years of Beemer knowledge to fix the problem.....

have a good day and keep smiling

[ME 109]

Done the zero clearance check, it quietened up the valve train a little as one would hope.
The knock is most noticeable on a cold engine at low idle. It fades as rpm picks up and is more difficult to produce a knock at operating temp.
Cold engine oil light test is >15 seconds.
The knock sounds to be timed with each revolution, and sounds to be in the lower front of the engine.
OK, it might be a half knock half rattle.
Other than the 'bit of a bogged down' feel to the bike, due ( I think) to the slide needle position, it's OK.

There is also the issue of pinging or knocking at higher revs wot. I've not noticed pinging before.
But, I put the slide needles in the second notch recently which doesn't appear to be doing any favors.
Can slide needle position cause pinging?

I worry when the RS is off colour, It looks kinda grey. Why just earlier tonight I found myself rocking it gently back and forwards on the centre stand until it cooled.

[ontic]

This thread has my interest.
I am keeping quiet about the details (until it is in my hot little hands) so as not to jinx the situation, but there is an airhead I am just about to buy with these very exact same symptoms.
Runs great however at very low idle (the idle needs to be adjusted as it is idling too low anyway- otherwise I might not have noticed it) there is an audible knock in the lower front of the engine. Sounds like one knock per revolution. Though of course it could be a rattle that is 'knockish', maybe a loose timing chain... I don't know.
Has me a bit worried but the price is good, so I will take the gamble (unless catastrophe strikes in this thread before the cash handover!)
Keep us informed Jeff, I hope you manage to solve it. I hope I manage to solve it. I wonder if it is the same problem?

[George Ryals]

Try idling on one cylinder at the time. If the knock goes away, the knock may be excessive crankshaft end float. A slightly bent (or twisted) rod can make the crank move end to end when that cylinder fires.

[ME 109]

End float crossed my mind as well George, but I was reluctant to mention it due to my recent forum guessing.
Engine bottom end rebuilt nearly two years ago with end play being a little tight if anything. Rods were checked for straight as well.
I'll screw the mixtures in to stall a cylinder.