i'm gonna melt this bike to iron bars and then eat them bit by bit in my salad

[tb0lt]

Then i put them back on but I missed a tooth on the chain, so when i cranked, it did a clong-noise

gsdox, that could have been a valve getting bent. If I were you and wanted to avoid some VERY costly and time consuming repairs, double, triple check the cam timing marks before trying to start the bike. I know this would sound stupid, but under the circumstances, you are sure you didn't swap the cams between IN and EX, right? . If that checks out, honestly, the next thing you need to do before screwing around and shooting in the dark is to get that compression tester like you've been planning.

Also, what do you mean the tensioner is pretty stiff? A properly working one should be smooth and pretty quick to spring back when unlocked. It shouldn't need to be manually tightened.

In case you are still shopping for compression testers....

http://www.harborfreight.com/compression-test-kit-66216.html (not sure if it includes the correct adapter... but it has a few)

http://www.harborfreight.com/quick-connect-compression-tester-95187.html (Includes a 12mm x 1.25 adapter to fit the GS plug threads)

[bombjack]

spray some easystart (ether) in the air filter. If it starts and then dies, you have a fuel problem.

If not, your bike has an intermittent electrical problem.
I've had this too and it was driving me nuts. The bike would die after running great for days. Then it would'nt start no matter what I did.
Then, after countless hours of wrenching it would start and run perfectly again and I had no idea why... a few days later it would stall again.

It turned out that a connector near the fuse was corroded.  

[the mole]

thanks again all of you guys for your interest and suggestions! You are truly very helpful (not only now but at my previous posts as well).

I'll try to see the earth-thing again. If i have understood correctly, I should Connect car+ to bike+ and car- to an earth point that is preferably a bolt on the bike's engine. If the bike's problem is only this faulty earth, the above connection will solve/bypass it right? And therefore it should work, right? Sorry for being a geek, but i want to be sure that i got everything clear...

Another thing: When i adjusted the valves, i did it without the special tool, just like mark on gstwin.com did it, by removing the camshafts (and necessarily by removing the chain tensioner too) . Then i put them back on but I missed a tooth on the chain, so when i cranked, it did a clong-noise. I fixed it by trying to get the notches on the camshafts face each other at the coil's p/t point. I put the chain tensioner back in (pretty stiff) and then all sounded fine. But couldn't work/start/fire up of course!!!
So with the noises facing each other, the valves with good clearance and a new gasket, is there sth i might have screwed up at this operation? Sth to look at?

Another thing: the compression meter i decribed earlier with specs: 10x1.0, 12x1.25, 14x1.25, 18x1.5 will fit the bike's spark plugs size (i just don't know what this sizes refer to / how to relate them to the ngk dp8ea-9 specs, which i don't have)??

And last but (perhaps) most important: When I say the bike gives spark, i mean i can feel it at my finger. I cannot actually see the spark with my eyes (I'm not blind though), if that's what you mean when you talk of spark. I just take the connected spark plug out  and crank the engine. I don't see anything (I have done this at night too) but i put my finger and feel a little shock. That goes for both spark plugs, and is the same if the bike is jumpstarted or normally ignited. If I should see a spark, and what i get is just a weak spark, please say so

Thanks again guys!

!. Yes, you've got the earth idea right.
2. It sounds like you're not confident about the valve timing situation, so I'd definitely double check that you've got the valve timing and the tensioner right. Its not hard to get everything looking good but 180 degrees out, because the camshaft revolves at half the speed of the crank. If you use the special tool you don't have to disturb the cam/timing which makes life easier.
3. The numbers refer to the diameter and thread pitch of the adapters that fit different plug threads. I'm not sure what the GS thread is, but likely one of those will fit, someone else should know and come in..Sledge?
4. If you can't see the spark you haven't got a spark. If you stick your finger in there you should get a belt that makes you jump. Sounds like you've found the problem.

[bigfatcat]

Another thing: the compression meter i decribed earlier with specs: 10x1.0, 12x1.25, 14x1.25, 18x1.5 will fit the bike's spark plugs size (i just don't know what this sizes refer to / how to relate them to the ngk dp8ea-9 specs, which i don't have)??

And last but (perhaps) most important: When I say the bike gives spark, i mean i can feel it at my finger. I cannot actually see the spark with my eyes (I'm not blind though), if that's what you mean when you talk of spark. I just take the connected spark plug out  and crank the engine. I don't see anything (I have done this at night too) but i put my finger and feel a little shock. That goes for both spark plugs, and is the same if the bike is jumpstarted or normally ignited. If I should see a spark, and what i get is just a weak spark, please say so

Thanks again guys!

Compression tester specs refer to thread sizes - the gs uses 18 mm spark plug iirc

Compression test without a tester : seal an open spark plug whole with your thumb and crank the motor - you should feel a buildup of air pressure. None would be bad.

Spark plug test : always provide a path to vehicle ground to prevent high voltage damage to electrical/electronic components. Go to Youtube and search 'spark plug test' for videos that'll show you how, and what to look for.

[tb0lt]

Compression tester specs refer to thread sizes - the gs uses 18 mm spark plug iirc

Compression test without a tester : seal an open spark plug whole with your thumb and crank the motor - you should feel a buildup of air pressure. None would be bad.

Spark plug test : always provide a path to vehicle ground to prevent high voltage damage to electrical/electronic components. Go to Youtube and search 'spark plug test' for videos that'll show you how, and what to look for.

I've posted the correct thread size earlier in this thread. The spark plug thread size for the GS500 is 12 mm x 1.25 and therefore you will need a 12x1.25 adapter in the compression tester kit.

I've used the method mentioned by bigfatcat before and it is a good enough technique to compare between cylinders. I've seen some geniuses literally stick their finger into the thread hole though.....  

Although a good spark in open atmospheric pressure doesn't necessarily mean a good enough spark under compression, my usual technique to test for spark is to pull the plug in question, attach it to the plug wire, hold the threaded part or the hex part firmly against the cylinder head and press the starter button. Wear thick rubber gloves or hold the plug with insulated pliers while you do this unless you like high voltage shocks

[gsdox]

all right guys, after a relatively big interval, i managed to learn how to perform spark test right, and the bike gives proper spark...
Then i bought a compression meter, and guess what? The left cylinder gives 25 psi (!!!) and the right one is even better, it gives NONE (the gauge won't move from zero)!
I thought i had had compression because air was getting sucked in and blown out, but my stupidity prevented me even from the basic comparison of the pressure of air between  the two cylinders (the right one gives significantly less).
Sooooo... what i'm i gonna do now? Is it better to just trash the old f///ing thing? Or is it something easily fixable (i guess it couldn't be the latter but i have to keep the faith till the bike speaks itself up and asks me to have her turned into water pipes and door handles)

[The Buddha]

25 and 0 psi compression, OK I'd say your guage if F*(*&ed up or your method is. Even the worst would make over 50, in fact under 100 is almost trash. To get 25 and 0 you need to have no rings and no pistons.

Throttle wide open, even better if carbs are off, then fit the guage on tight without leaks, and it should crank nice and hard a few times till the guage stabilises @ the number.

Cool.
Buddha.

[kml.krk]

very interesting thread!
I hope you get it fixed.
Do not give hope on that ol' GS, she'll love ya once you fix her

[gsdox]

thanks buddha, one thing is for sure, the throttle wasn't wide open, not open at all (and the carbs were on...). I'll try that again... tomorrow

[gsdox]

Oh and thank you kml.krk for your wishes. I have a vague idea that it wasnt meant to be< you know< between me and her! anyway if anything good arises< you will notice!

[aygee]

and if you get a low reading on one cylinder, put a teaspoon of 2T oil into the bore and retest - if reading improves significantly you're looking at rings, if not valves...

[the mole]

thanks buddha, one thing is for sure, the throttle wasn't wide open, not open at all (and the carbs were on...). I'll try that again... tomorrow

Yes, the compression tester is measuring the pressure of the air in the cylinder after it has been compressed by the rising piston. If the throttle is shut, you don't get much air in the cylinder=low reading.

The other thing that would give you a low reading is if you did bend the valve when you heard that loud 'clang', that would read zero for sure.
Another possibility is the cams are not correctly synched with the crank, which can happen if you've been messing with the camchain.

[scottychop]

This might sound newbie-ish but I just went through the same problem exactly.  Did  you check to see if the new plugs were wet after cranking?  I went through ever single step of your dilema and found the plugs were not getting fuel.

[scottychop]

Any progress??

[Vova]

I have to admit I only read bits and pieces, but a lot of what he describes sounds similar to what I feel when running out of gas. Is it possible it is as simple a problem as some clogged/warped fuel lines that are not allowing proper flow?

[Twisted]

I am still hoping the OP is going to melt this bike to iron bars and then eat them bit by bit in his salad. 

[gsdox]

guys, after getting fed up with the problems, i decided to swap the engine...
I guess I have caused a problem to the valves or something, but since i faced problems getting the engine to work before as well, I considered letting it go (the engine already had 87000km) and decided to find another one. Which i did. And it works, let's see how well...

[mass-hole]

You ever try pouring a little gas in the sparkplug hole, putting the plug in and seeing if it will start? If it doesnt then it seems like it might be an ignition issue.

[The Buddha]

You ever try pouring a little gas in the sparkplug hole, putting the plug in and seeing if it will start? If it doesnt then it seems like it might be an ignition issue.

Do not do this. You will end up with hydrolocked motor and can cause all sorts of fun. Like bent rods.
Cool.
Buddha.

[gsdox]

I had done that (gas in the sparkplug hole) more than once. So now I can't be sure about the extent of the destruction i have caused to the previous engine . Which is a shame, as it did have fired-up a couple of times (lets say 10-15 times to be fair) in it's now-almost-over-a-year period of my ownership of the bike. Poor engine, if it had been in better hands, it would have gotten some thousand kilometers more down the road...