Best way to loosen tight hex bolts

I'm trying to get the cap off the side of my GPZ 550 engine to hand turn the crank and see how the pistons feel, but the Allen-type hex bolts are proving stubborn. Got them hosed down with some PB Blaster, but wondering what the best approach is to loosen them while minimising the risk of stripping/rounding the inside of the heads?

I suppose from worst to best would be Allen key - hex socket - impact wrench with impact hex socket? How would normal hex sockets versus the rounded-head ones compare?

Thanks!

I assume you're talking about Allen head bolts, in which case they are probably stainless, and they probably didn't have anti-seize applied to them before they were put in. PB Blaster and patience is what it going to take but a little heat never hurt anyone either.

I just use a regular Allen wrench to take off side covers on my Gpz550. You might tap lightly on the bolts with a hammer to break loose the corrosion that may keeping them tight. I was trying to take the Allen bolts loose on my forks this weekend and could not do it with my wrench, so I purchased an Allen socket.

When they are stuck, take a flat nosed punch that fits inside the Allen. Then give it some firm hits with a hammer. Instant impact wrench.

Awesome I wasn't looking forward to forking out green for a set of impact hex sockets Will probably just invest in some good quality allen keys or hex sockets ... don't want to screw up the bolts due to poor quality tools

In terms of anti-sieze compound ... can anyone recommend a good brand to use? Also, which bolts should it be applied to and which should have locking compound on them? I know in the service manual it specifically states that some should have locking compound ... all others anti-sieze?

Thanks

I LOVE PB Blaster! For two days I just went out and sprayed almost every bolts on the bike with a little. Today I took a wrench and hex socket and undid virtually everything with ease Awesome stuff!

Any advice on anti-sieze an locking compound brands?

I use a brand made by Permatex, it's silver type that I use on the first few threads of sparkplugs,axles of the wheels(a little goes a long way, so a thin film works best.) It comes in a 1 oz or 28 gram squeeze tube available at most auto parts stores.

It prevents seizing or galling,prevents corrosion and is good for high temperatures 1600 F (870 C).

I second the Permatex antisieze compound. We use it on F-15s all ove the place. But for penetrating oil, we use a brand called Kroil. And it is some amazing stuff, especially on stainless bolts in Aluminum castings and forgings, plus monel, titanium, berylium, you name it.

+1 on the Kroil! It really works! Ed

I personally like to use a torx-bit (which I hammer in first) and loosen it then with an impact driver.

The torx bit is a bit bigger, but has some sharp edges, ideal to create extra grip.
(BTW use penetrating oil before, and let it sit overnight before you even try..)
(this trick works on metric alan bolts, no idea how it works on others)

try mixing acetone with trany fluid 50/50 works great for stuborn bolts.