I bought a compression tester so I'll give it a shot and report back with the results soon.

These bolts sure are a pain... I looked all over the bike and the exhaust bolts are the only ones in such terrible condition. I would've thought the front bolts holding the oil filter cover would be just as bad but they are pretty rust free.

I'll save drilling out for a last resort. I'm not even sure on how to do that but it seems way too easy to damage the head that way. I can't get access to a welder so can't go that route either. Once I get them off (IF I get them off) I'll definitely have to replace them with new bolts or studs.

I definitely was guilty of the imperial vs metric mistake. I just grabbed the one that looked the right size, saw that it fit, and started turning. It very well may have been the wrong size... I'll let that be a painful lesson learned =(

Nutmunk, I bought an easy-out but it's not any industrial strength kind and it looks like it's meant to take off screws and bolts that aren't rusted tight. Never used one before so I don't have much faith but I'm going to take off the front wheel and guard anyways and give it a shot. Going to give this Irwin bolt extractor a try too (http://www.amazon.com/Irwin-Industrial-Tools-394001-Bolt-Grip/dp/B0000CCXVZ/ref=sr_1_1?ie=UTF8&qid=1373329666&sr=8-1&keywords=irwin+bolt+extractor#productDetails). The reviews seem good and it seems like it may work.

Joolstacho, yep I'm going at it on my own! Two days in and I've already hit a big snag and I'm sure this is only the tip of the iceberg. Thanks for the encouragement and thanks to everyone for their replies, I'll be sure to keep this thread updated as I go along. Here's a photo for everyone. She just sits in my garage silently waiting for me to get this dang bolt off...

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It might help to soak it in some deep creep or penetrating oil before the next attempt.

Also, remember the 'heat-spanner' for those 'bastard' seized bolts/nuts!
Try using a MAPP gas torch or heat gun to heat up the area around the seized nut/bolt, you'd be surprised how often this works when other methods fail. And... cautionary note on 'Easy-outs', -yup they can work, BUT if one snaps inside the drilling you're done for... they're super-hard and impossible to drill out.
-Jools

Just a note for easy outs as well...I don't use then in a drill ever!!! Use an adjustable tap wrench...they offer a lot more control so you have less chance of snapping it off.

Touch wood, but I haven't broken one yet.

Normally what I do is q20 the shizness out of the bolt as well just to get some lube in as well.

Good luck bud.

Here are the compression test results... not quite sure what to make of it:

Left cylinder: just a tad under 150 psi (145? 147?). Seems to be good.
Right cylinder: barely any compression... about 13 psi

I put a spoonful of oil in the right cylinder, tested it again, and it bumped up to about 30 psi.

I wasn't able to do a test with the engine warm, I don't think it would make much of a difference, would it? I read that a noticeable psi  increase after putting oil in the cylinder would point to cylinder, piston, or piston ring damage... 17 psi doesn't quite count as noticeable I would think. So all should point towards the exhaust valve?

I've been spraying PB Blaster at the header bolts for a few days now to no avail. I'm waiting till tomorrow to pick up those Irwin bolt extractors and give those a shot. If they don't work, I'll be working my way down the list of suggestions that other people posted.

Looks like a confirmed valve problem.

Yeah, as robust as these engines are, they still need moving air to cool them.  the stop and go does heat em up really good and yes you can overheat these engines. while they may not be hurt in the bottom end (crank and counter bal shaft) the top end is what cooks,   here is most likely what happen and your compression test kinda confirms it.  the engine got hot enough to cook the oil off the exhaust valve and it started sticking, when this happens one of 2 things happens, exhaust sticks open and it meets MR piston  or it sticks open and MR's intake valve pushes his ass out the way.  it didnt have any power as you were running on 1 cyl.  once the bike cooled down the valve guide released its death grip and let the valve move again giving you your current tapping. the valve isnt closeing all the way which is why you have no compression in that cyl. the heads are pretty tough, alot of times you can get away with replaceing the damaged valve,  dress up the valve seat a touch, the guide might need replacement might not, it would need to be checked, and replace the valve stem seal. when doing this kind of work its a good idea to have all the valves freshend up with a lapping and stem seals. THEN you need to redo the valve lash.   I think kerry had a kit circling among the twiners here. you will have to redo the lash on all the valves once the valves have been done.  if you can get ahold of the tools, you can do all the work, its not hard.      easyer still is find a half decent head, relap the valves, change the valve stem seals and bolt it on with fresh gasket and O-rings

oh, as to your exhaust bolts, even if you snap em off,  dilling them out with the head on a bench is far easyer to deal with.

Hey guys, unfortunately, the DIY route isn't going so well. Those two bolts absolutely refuse to come off for me. I'm sure someone with more experience would have the tools and know-how to get them off. I even resorted to try drilling them out but when I went to take the front wheel off, I ended up rounding another bolt and partially rounding another nut  I made sure to have the correct fitting imperial sizes this time so the only reason left is that I have some pretty crap quality tools (which could be a possibility).

I decided to just rid myself of the headache and took it to another shop. I'm sure any mechanic would have dealt with their fair share of rusty bolts so I'll leave it to the experts. He was backed up this whole week (small shop) but he said to give him a call next week and he'll be able to do a leakdown test to tell me, money-wise, if it's worth saving or not.

I'd also hate to do this but at this point I'm considering selling for a loss as well. I have no clue about what my bike is worth anymore though so I'll make another post asking for people's opinions.

Quote from: Blueknyt on July 10, 2013, 08:40:37 PM
oh, as to your exhaust bolts, even if you snap em off,  dilling them out with the head on a bench is far easyer to deal with.

Blueknyt - you're back ... Blueknyt rises ...
Cool.
Buddha.

Yeah im back Budda, might need some of your carb magic as ive been outa the game for awhile.  some if its coming slowly back.  AlexT, the bike is paid for, its a good bike. get the bolts off, even if they break, you can deal with them later, or have the shop deal with them when you hand them the head and new parts to do the valves job for you, worse case if the head is shot, broken bolts will no longer matter, you turn your concern to another head.   here is one thats not bad according to pix
http://www.ebay.com/itm/Suzuki-1993-GS500-GS-500-GS500E-500E-E-Engine-Cylinder-Head-/380679876835?pt=Motorcycles_Parts_Accessories&hash=item58a249f0e3&vxp=mtr

price isnt too terrible and includes shipping. have a machine shop to a quick valve job on it and change the valve stem seals and you should be golden.

Awesome, thanks a lot Blueknyt. I'll be back to update by the weekend.

So I realize I never did update this thread... so in case anyone is still interested in how this is going, here's an update nearly a month later.

After my last post, I had to go back to the shop 2 times for him to have time to take a look at my bike. Unfortunately, after one of those visits, I dropped my bike for the first time (the shop is up a hill on a dead end street, tricky for a new rider). Definitely going to have to practice low speed maneuvering on hills once I get it all fixed up. When I went back to the shop a second time, he did a leakdown test and confirmed it was a valve problem and I left the bike there while I went online to round up some parts.

Here's a list of parts that I bought:
- used head off ebay
- head gasket
- o rings for head bolts
- exhaust gaskets
- R&G frame sliders (paranoid about dropping my bike again!)
- vortex clip ons (old handlebars bent with the drop)
- clutch lever (so did this)
- bar ends
- foam grips

The parts came in slowly over the past few weeks and I just brought them all to the shop today. If all goes well, I should be riding again by next weekend!

Take a look at the damage the overheated engine caused. The valves were fine surprisingly! But there's a chunk missing from the seat on the head. The first picture show light peeking out from behind the valve where the missing chunk is and the second picture shows the damage. I didn't snap a picture of this but those two stubborn exhaust bolts were seized beyond belief and the mechanic just cut them off at the head.

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Nevermind, didn't realize this was up to three pages already.

Quote from: Blueknyt on July 19, 2013, 10:34:14 PM
Yeah im back Budda, might need some of your carb magic as ive been outa the game for awhile.  some if its coming slowly back.  AlexT, the bike is paid for, its a good bike. get the bolts off, even if they break, you can deal with them later, or have the shop deal with them when you hand them the head and new parts to do the valves job for you, worse case if the head is shot, broken bolts will no longer matter, you turn your concern to another head.   here is one thats not bad according to pix
http://www.ebay.com/itm/Suzuki-1993-GS500-GS-500-GS500E-500E-E-Engine-Cylinder-Head-/380679876835?pt=Motorcycles_Parts_Accessories&hash=item58a249f0e3&vxp=mtr

price isnt too terrible and includes shipping. have a machine shop to a quick valve job on it and change the valve stem seals and you should be golden.

New custom title for you.

yep. you need a new head.

i gotta say, ive seen valve seats drop, and get chewed, ive never seen one bust apart still seated......... must have been REALLY REALLY hot.

or something hard was floating around in there also?

Attached is a photo of the new head (which should be getting installed as I'm writing this). Believe it or not, it actually is a head off of a 2004 engine but the previous owner had spray painted it black for some reason. The head was in good condition when I bought it but when I opened the package, I found that a cooling fin got cracked during shipping! Goddamn...

The mechanic said the same thing. This is probably the first time he's seen a seat break like that before. He said more than likely, my valves clearances were way tight to begin with and sitting in traffic was the tipping point. The chipped piece either disintegrated or got shot out of the exhaust because the pistons and cylinder walls were undamaged (thank goodness!  )

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yeah, the fin broken wont hurt you, if 50% of the fins were like that then it might be an issue.   tight valve would have made no difference, it just wouldnt seal very well and bleed hot gasses back into the cyl on the intake stroke kinda like spoiling the mix.  however, the valve seats are just rings of steal that are harder then aluminum, they dont expand and contract as much or as quickly when heated. they are held in place by interference fit.  ive seen the aluminum head expand enough to loosen the grip on a valve seat and have it drop (but there were signs of catastrophic heat levels elsewhere too)  BTW, its a good way to remove snaped bolts too. warm up the aluminum around the bolt with a small propane torch.  ive also seen the "Canned Air" turned upside down so as to super cool the bolt shocking the threads .  but NOS or R22/12 works better in that reguard