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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: BobR on February 25, 2012, 04:55:30 PM
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Doing routine maintenance on my bike (91 K100 RS) and started it up in my garage to warm it up for an oil change. Valve noise was particularly noticeable for some reason. so I am wondering if it is more than usual, etc. I usually drive with ear plugs so it has been a while since I started it up in an enclosed area like this to listen, so very possible this level is not anything new, just for some reason seems loud to me.
So, bottom line is, and I know this is hard to quantify, but how does one know if there is too much noise to the point where I might say that the valves need adjusting or something similar? Bike has been running great, no known issues that I am aware of. Just seeing if some of the experts can help me calibrate my ears on this, or maybe there is something else I can check to verify. Thanks...
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Are you sure it's valve noise and not timing gear? Timing gear noise at idle is fairly common on the 4V bikes.
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could also be fuel injectors. check the valve lash if you are worried.
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Are you sure it's valve noise and not timing gear? Timing gear noise at idle is fairly common on the 4V bikes.
Not sure I know how to tell the difference. It sounds like...tap tap tap tap tap....
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I can't say I recall much (any) valve noise on mine, and two were out of spec. Is it possible you have a slight exhaust leak?
The other option would be to use a stethoscope (or rubber hose or wooden dowel) to try to further pin point the source of the noise.
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I can't say I recall much (any) valve noise on mine, and two were out of spec. Is it possible you have a slight exhaust leak?
The other option would be to use a stethoscope (or rubber hose or wooden dowel) to try to further pin point the source of the noise.
Or a screwdriver. Press the handle against your ear, and plug the other one.
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If it's a steady tap, tap, tap then it's probably not timing gear. Timing gear has more of a "box of rocks" sound to it.
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My noisy valve gear drove me nuts until I put new alternator bearings in! I found some issues in the valve gear when I had it all apart but the step change in reduced rattling on my bike was new alternator bearings.
I'd convinced my self it was valave gear too as the rattle sounded just lik the cam chain tensioner rattle on old Hondas
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My noisy valve gear drove me nuts until I put new alternator bearings in! I found some issues in the valve gear when I had it all apart but the step change in reduced rattling on my bike was new alternator bearings.
I'd convinced my self it was valave gear too as the rattle sounded just like the cam chain tensioner rattle on old Hondas
Interesting, as my hi mileage K 75 has a weird "tap tap" noise during cold start ups. (10 degrees or lower)
Truthfully speaking, I NEVER thought about the alternator bearing, which does make perfect sense.
Did your noise go away once the engine warmed up some ? (2 - 3 minutes)
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It was horrible on start up and then went away but right when I pulled the alternator it started to sound like a bag of spanners was loose in the fuel tank.
Pulled the alternator apart and a collection of dust fell out of the rear bearing (or at least what should have been the rear bearing - put it all back together and no more bag of spanners.
My K still "knocks" a little on start up but goes within 2 or three seconds so I'm figuring that is more likely valve gear or specifically the tensioner.
Someone who's been around bikes for far longer than me and BMWs for specifically for 20 years suggested its not uncommon for the Cam chain tensioner on the K to slacken off a little when standing as it relies on its hydraulic element as well as the spring to fully tension. Apparently the heads are safe enough in design to do this which explains how my bike ran with the inlet and exhaust cam both out against tdc on the crank courtesy of the previous owners muppetry !