Freeing frozen valve cover bolt with heat

[Guest]

I’m working to replace a leaky valve cover gasket as well as check the valve clearance on my new-to-me 1982 GS1100GZ. One of the stainless steel bolts securing the cover was stuck, and I applied too much pressure such that I broke the top off half inch off of it. Fortunately I was able to get the valve cover off with the one bolt still in the cylinder head, such that I now have about 3/4th of an inch sticking up. I can get vice grips on the shaft, but with the hex head off can no longer use a socket set on it. When I try with the vice grips I still can’t get it loose.

Ive tried PB blaster and liquid wrench over the last couple of days, as well as hitting it with a hammer to shock it loose, all to no avail. I have a MAP gas torch, with the understanding that I should try to heat the aluminum head around the bolt to try and loosen it. My question is, with the valve cover off, the areas around the camshafts for the valves that are normally bathed in oil is less than an inch away. Do I need to be concerned about applying heat close to that? Should I cover that area with tin foil in case the flame inadvertently comes close to it?? I’m purely guessing here, this could be a big safety no-no, or I may be totally overthinking it...

Thanks,
Matt

[Grimly]

If it's a front bolt, you're laughing. A middle or rear bolt is slightly more awkward.
Just aim the flame at the root of the bolt, avoiding bathing the oil in flames. About 10 seconds will probably do it, if not, try successive shots of 10 seconds at a time. The repeated heating will encourage it to loosen off. If it still refuses, try a bit longer, like 20 seconds at a time.
There's no great risk of fire or explosion, but just be wary of inadvertently frying your wiring loom, etc.

[Fxvielander]

Great thanks, sounds goood. Yes it’s a middle bolt in near the centerline of the bike near the timing chain.

[Big T]

Just keep a wet hand towel at hand