so by the time you hear your valves knocking, are they ready for a shim? Mine seemed to knock when cold today, but after 5-10 minutes of riding (fully warmed up) they stopped. I measured recently and the clearance on exhaust 1 was pretty slim (>0.038mm, my smallest feeler).
time to get them simmed? yes? no?
peace.
Nope, you're fine. It seems that these bikes, when subjected to extreme cold, the valves tap because the clearances become so tight. Both 70Camguy and myself have experienced this.
oh, sweet... that's really good to hear... the only other sound that concerns me is a light clinkin' in the top of the engine during warmup as well... could that be the valve clearances as well?
peace
Yep.
MINE DOES EXACTLY THE SAME, 75.000 KM AND NO PROBLEM! :thumb:
wow... awesome... I guess those air-cooled engines just make noises a they age, huh?
I'm glad to hear that I'm not the only one dealing with 'mystery noises' during warmup.
thanks! :mrgreen:
Valves clatter because of being loose... not from being tight. Now as it gets colder they get tighter, hotter makes them looser... but that thermal expansion is so little you dont have to worry about it... Just for the academic interst I checked when hot... burned my fingers and found that its slightly looser. Now clatter doesn't make it too loose. As you begin to hear the clatter... My guess (from experience) is that you are right in the mid point of the range of clearance. As it gets towards the high end of the clearance it makes more of a racket. So You are about right where it should be.
Now (Juanfer) 75K wihtout a valve adjustment ... well in 45K miles I have done ~ 4 per valve. So I hope you are checking it to make sure you aren't burning something.
Cool.
Srinath.
QuoteValves clatter because of being loose
Correct, they will also make noise if guides are worn out
QuoteNow as it gets colder they get tighter, hotter makes them looser
Incorrect, Valve lash decreases when warm, the valves dont just expand round the stem, they expand length of stem too. this closes the gap.
the reason you think it felt More loose when hot, (couple reasons) fresh lube is now coating the parts, making them slip allittle easyer. valve guides can both loosen and titen with heatsoak.
If the valves got looser when hot, we would be adjusting them to the tight side of no clearence, and letting them loosen up as they get hot, this isnt the case. Most racers(that i personaly know) adjust their valves a touch on the loose side of the wide clearence specs to compensate for Higher heat of hard running.
ok, now im gonna put my brain back to bed, the light show is getting wicked again and its taken me 2x longer to write this then normal (fevers, got to love em)
Well valves expand with heat. So they do get longer. But the head also gets hot significantly... well agreed its a bit less than the valve face and the lower stem so the distance from the valve seat to the cam end cap also increases. That makes the valve looser. Agreed the valve will be hotter and hence will expand more, but the head in aluminum, and that expands a lot more under heat than steel. These 2 will nearly even out each other, but depending on some other factors they will either get loose or tight to a small degree. Yes hot lube is less resistance, but that doesn't mean a ticker feeler guage will fit. I have been able to shove in a thicker feeler guage under a cam when it was hot, and not been able to after it got cold on a GS. On a different model, for example water cooled bikes I can see how it will be significantly different cos the head temp is very very much lower than the valve temp but on a GS its looser when hotter.
Cool.
Srinath.