k bike rattle

[REILLY]

I know that this has been covered. general thought is that the alternator rubber dampners are the cause. My 1995 bmw k75 rt has a rattle up to 2000 rpm thru the gears.. Has 65,000 kilometers.
I changed the rubbers although they looked good.
still get the rattle.. anything else that might be the cause.
Bike and me are new to the site. Cheers. :type

[BuddingGeezer]

A loose timing chain will cause a castanet type rattle at lower rpms. As the engine revs centrifugal force tightens the chain and the rattle goes away. Usually the tensioner spring gets weak. I don't know if this is a normal problem for brick engines, it is for many motorcycles. The tensioner guide can also wear.

Ralph Sims

[SugarHillCTD]

From what I have read (and experienced when I had the timing cover off to reseal a leak) the timing chain is tensioned by a spring AND by oil pressure.

The "rattle" goes away as the RPMs increase for 2 reasons:

1) as BuddingGeezer indicated- as the revs increase, so does the centrifugal force on the chain

2) but also- as the revs build, so does oil pressure which increases pressure on the tensioner.

This is my understanding- but Paul Glaves (he is here on the site) is THE wizard and I definitely bow to his correction if I am not accurate.

BTW Reilly, welcome.

John

[brewmeister]

:bar :banghead :banghead I had a number of rattle issues. 1. loose muffler heat shield. 2. A loose internal baffel in side of my muffler. I figured it out when I tok it off and shaked it back and forth. I was missing a screw that holds the radiator cowling on which rattled only at certain RPMs.

[Ridealot]

The shape of the K75 muffler is a triangle. I don't think they had the rattle problem like the K100's square muffler. It's easy to check though. Just ride at the RPM that causes the rattle and then put your boot against the heat shield. The rattle will go away if thats it.

I put over 130K miles on a K100RT and the heat shield rattle would definately drive you Bat **** Crazy. The cure was to unbolt the heat shield and then throw the thing as far as you could. Then cut off the tabs that held the heat shield nuts to make the muffler look a little bit better.

[tvguy]

Rattles what rattles!

This phenomenon should be called by it's correct term....character.



:hide

I feel much better now

[REILLY]

Thanks for the replies..its not the heat shield..I like the "character" response.
I have a lot of rattles too in my elder years so I guess you could say my bike and I are in perfect harmony.