Valve Adjust - How cold is cold enough?

[PacWestGS]

I need to adjust my valves. Question - how cold does the engine (valves) need to be to get it right. I just got home two-hours ago and the engine is cool-to-touch. In the morning it will be garage temps of 45-50 degrees F.

Should I wait?

Doc

[Godfather]

I read the temp of the engine should be less than 90 degrees F.
I will try to find the article and post it.

[Mika]

If the engine is lay your hand on it and leave it there warm you are cold enough.

[PacWestGS]

Thanks, be in the garage working... :thumb

ciao

Doc

[PUDGYPAINTGUY]

Ambient is cold enough Russ, tough to be any cooler without parking in the fridge...lol.

[PacWestGS]

I'm done, top exhaust valves were a little tight on both sides. Now she's purring like a kitty. Valve adjust and throttle sync - ready to go for awhile again.

Thanks Guys

Russ

[The_Veg]

Late to the discussion as usual, but my understanding is that the 'cold' recommendation is really sort of pointless. If thermal expansion is enough to throw off your clearances, then it would also be enough to cause serious problems with the simple operation of the engine. I've heard old-school airhead mechanics say that as long as they could do the job without burning themselves, it was good and remained so for a reasonable service interval.

[wildwilly]

Who makes the crash bars on your GS? Thanks.

[PacWestGS]

Who makes the crash bars on your GS? Thanks.

They're OEM BMW Adventure bars and skid plate. I added them becuase the bike should have them and they make the best "Highway Pegs" for the long haul.

The Hepco-Baker bars probably protect better but I went for the comfort model insted.

Doc

[PUDGYPAINTGUY]

Late to the discussion as usual, but my understanding is that the 'cold' recommendation is really sort of pointless. If thermal expansion is enough to throw off your clearances, then it would also be enough to cause serious problems with the simple operation of the engine. I've heard old-school airhead mechanics say that as long as they could do the job without burning themselves, it was good and remained so for a reasonable service interval.


This makes sense as the ambient is 120F in places where BMW's are sold and I don't see any recommendations for adjusting valves in an air conditioned room LOL...

[PGlaves]

I've heard old-school airhead mechanics say that as long as they could do the job without burning themselves, it was good and remained so for a reasonable service interval.
Not to be too irreverent, but lots of airheads developed a "reasonable" valve adjustment interval of 600 to 1,500 miles, because any longer than that and the exhaust valves might close up completely.

[The_Veg]

Were those the receding ones or...?

[PGlaves]

Were those the receding ones or...?
Not actually valve recession usually. Valve recession technically results when seats wear and the head of the valve sinks ever deeper and deeper into the worn seat.

In the 1980-1984 models BMW installed new, hardened valve seats. And the valves often frequently closed up the gap on the exhaust valves. Shops would take the heads apart and find the heads of the valves deformed. Assuming the valves were bad (and they were by then) the shops replaced the valves. Since the seats looked pristine most shops replaced the valves and did nothing to the seats.

After a few years BMW figured out that the seats were the real culprit. They were hard. They didn't wear. But they also were very poor at transferring hear from the valve heads. This is why the valves were overheating and deforming.

When BMW introduced new seat metalurgy for the 1995 models they corrected the problem. And by then the shops knew they needed new seats as well as new valves to correct the problem on the earlier models.

[The_Veg]

Right on Paul; I kinda though we were on the same page but I just wanted to be sure.
My earlier point was merely about heat and metal rather than the hisotrical subtleties of airhead valves and seats. :)