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

[gsdox]

WHOOOOOOOOOOOOOOOOHHHHHOOOOOOOO!!!!!!!!!! :cookoo:YHEA!
The bike has the same problem again (see first posts for that, but in a few words, after a 20' of riding solo in a warm day -say around 28-30 celcius- it started stuttering in the highway, not being able to rev up. Thank god i managed to get her home-the final 500 meters pushing it) WITH THE SWAPPED ENGINE!!
So I am a proven dumb ass as i have swapped an engine that was already ok (well maybe i have trashed it a little bit by that valve adjustment thing, but anyway... )

Now back to the same with a big hint (that costs 320euro); it can't be the engine or the carbs, as both are swapped (and i can't believe i would be so unlucky to have got a set of faulty ones again from a crashed bike whose engine i saw working properly). So it's the electric, coils? ignition?
God (or allah) I hope i can get her to start, as the first time this thing happened, I was unable later to make her start as if keeping the engine running (to get back) on stutter (trying to rev up to move a little and then rolling on neutral) till she finally went out and didn't fire back on (which i then thought was due to the heat), somehow damaged the whole thing and wouldn't let it start up again. Anyway then I made a lot of mistakes the same time. Now (without needing to be in panic, as the bike is at my place) i will take it slowly, trying to avoid the crap i have been through the last time...

[Big Rich]

Make sure the battery is charged 100%. Then test for a big fat spark on the plugs you are using (not some plug you have laying around). Check the cold compression on both cylinders (will be lower than a hot compression test, but they should be within 10% of each other). Make sure gas is in the float bowls and try to start it again. If it still doesn't start pull both plugs and make sure they are wet with gas. If they are dry, then your carbs aren't clean. If they are wet, then your timing is off (not likely).

Anything else?

[Big Rich]

One more thing: I know that OLD coils begin to fail by missing at higher rpm's. As they get worse they will actually stop working when they heat up. But after the motor cools down (about 30 minutes) the bike will fire up and run again.

When I say old coils, I mean coils from the late 60's / early 70's. So they probably aren't your problem. There should be a test for checking the primary and secondary windings in the service manual though.

[The Buddha]

The crank trigger coils usually die when hot. In fact there have been cases where they continue to work when you keep the revs up but die when you close the throttle.
I also have had it fail in 1 cyl when hot only.
You could have that happen, unless you got a new crank trigger with the new motor.
Cool.
Buddha.

[gsdox]

Thank you all for your suggestions!

Budha could you show me exactly what and where the crank triggers are (if you have the haynes manual you could point me to a page-photo)? I would very very much appreciate it, as i don't have a clue...

[ben2go]

Thank you all for your suggestions!

Budha could you show me exactly what and where the crank triggers are (if you have the haynes manual you could point me to a page-photo)? I would very very much appreciate it, as i don't have a clue...

They are under the round cover on the right side engine case.Three bolts holds the cover on and there should be no oil in there so no gasket to worry with.

[ramennoodles]

I had issues too.  I went and cleaned all my electrical connections with wd-40 and it never had any more problems.  The ones I notice had the most corrosion was the ones under the seat by the fuse.

[gsdox]

unfortunately i got a whole "new" engine box, i mean with crank trigger and all. So i guess it shouldn't be that...
Now owning the bike for a year and the only kilometres i've ridden on it are those that have resulted in me pushing it 

[gsdox]

If anybody has faced a problem in the ELECTRICS section, a problem that would cause the bike to run poorly, stuttering, working only if you rev up, then more stuttering and finally going dead once and for good PLEASE GIVE A HINT!!

I can't think of anything other than changing the whole electric set of the bike. But that would be a huge pain in the ass.
The most  characteristic thing of the problem i'm facing is that with the new engine, the bike did work. Then i took it for a ride 2 up no prob. Then i took it for a ride myself and it got f@#$d up again.
AND NOW IT WON' T EVEN START!!

The previous owner had told me that someday there had been an attempt to steal the bike using a screwdriver in the locker-ignition-key slot (how is this thing called anyway?) and that any key would do to start it. Does that have sth to do with the prob?
(maybe a silly question but as i have faced completely similar problems with a kawasaki kle i owned with it's key slot also abused-don't ask me if that had been the issue, i didn't have enough nerves to fix it- i'm just wondering)
PLEASE HELP as i'm starting to believe i'm cursed

[gs500e]

The locker-ignition/key-slot dooooohickieee is called an ignition switch  (nope, it is not called that, because on some cars the ignition switch is on the steering column down by your feet) is called a lock cylinder (which on some cars is connected to ignition switch by a metal rod).

Anyway.... i am going to melt my bike down to metal bars also.  Weather gets good and it has been in the shed the entire time; well, except when i take it for a spin and it dies on me, or spits and sputters, or won't go above 3/4 throttle, or runs great for first five miles... then i'm sitting on the side of the road trying to do the whole 'i'm not emberrasssed my bike is broke down... i just think it is so bad ars that i pull over, get off and look at it for a while' thing.  Then get on it ten minutes later and it barely runs right long enough to get me home.
I sent my carbs out for a go-over, haven't heard back on them, ordered another set off ebay, same problems.... well slightly worse now, plus i forgot to hook up crank vent (i tucked it up under the frame in a kink to get it out of my way, forgot about it.... spewed oil out of engine seals..... fun stuff).
I think i will check the valves..... grrrr.

GRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR.

Good luck with yours.

Maybe your ignition box died?  (or a wire to/from it?)

[gsdox]

thanks gs500 for your answer. The thing is I just have an update; I changes the ignition box as you suggested and the bike did fire up. Hesitantly, you could hear it spin just like before, but once in a while there was this trying-to-start sound (as though on one cylinder, or just like before, when it was running and was going to die till it finally did). Then i swapped the coils too and it was the same. The final thing i did was to swap that fuse tin haynes manual p 8.17 pict 28.2a. By that time the engine was running normally (or in a way that it seemed normal). I warmed it up for good. Then I swapped back the ignition box and with the old one it was also running the same way. Then i swapped back the fuse and it was also running...

Even though the engine now starts and runs fine (or so i believe) I can't feel secure with this bike. I'm worried that i will make a few kilometers and then it will get screwed up again....

[xunedeinx]

I know with some cars i've hard, the plugs and connectors get corroded and loose contact. Unplugging and reseating them may have made enough contact to make a circuit, but in th future will do the same thing again, leaving you scratching your head..

-Justin

[gsdox]

there's this thing that i keep wondering about.The battery has lost liquids just where the ignition box is, and the metal part where the ignition box is held screwed onto, is corroded (you know, that white thing like mucus that corrodes metal when electrolyte is spilled over). So i scratched that part to get some of that white thing out.
Now IF the ignition box IS GROUNDED to that metal part, that white thing might have prevented grounding...
That would be a good answer if the ignition box needs to be grounded, if not, i'm talking bullshit again

[bigfatcat]

there's this thing that i keep wondering about.The battery has lost liquids just where the ignition box is, and the metal part where the ignition box is held screwed onto, is corroded (you know, that white thing like mucus that corrodes metal when electrolyte is spilled over). So i scratched that part to get some of that white thing out.
Now IF the ignition box IS GROUNDED to that metal part, that white thing might have prevented grounding...
That would be a good answer if the ignition box needs to be grounded, if not, i'm talking bullshaZam! again

The ICU (ignition control unit) is not grounded that way.

Ground  for the ICU is black/white wire from the four pin connector, goes to battery neg terminal.

[bombjack]

Hi,

I hav had a problem like yours and it was the spark plug cables that would fail when they got hot. It was easy to fix though.
Take off each spark plug cap, and turn it one or two full turns clockwise and reinstall it.
It's worth a try. It won't cost you anything and takes less than a minute to do.

[gs500e]

FWIW: I was tinkering with mine doing the same thing as yours.
I set up the gas tank (hanging from a rafter above the bike, so i could work on it and run it at same time) directly to the carb... aka: i bypassed the frame mounted petcock.  It started up and idled on choke until warmed up, and then idled and revved fine without choke about a minute after initial startup.  (this doesn't make much sense, since i can turn of the fuel at the tank and the bike will run/idle low revs for a good minute or three... with no gas going to carb... so.... i guess the frame mounted petcock was just FUBAR and really restricting gas flow... unexpectedly).

Suspect your frame mounted petcock. 
I had previously tested it by applying vacuum to it, and then seeing that i could blow through all the ports... which i could. 
So i have to imagine my bike is not making good vacuum at idle... or at all.... for whatever reason.  I unplugged the hose going to the petcock vacuum, and the engine stumbled and stopped... like it had a vacuum leak, so it 'should' have worked.... but it didn't.  It's on it's way to a trash can.

I took the frame mounted petcock off, and took it apart.  I found nothing obvious wrong with it (vacuum side was dry and clean, fuel side was wet from fuel and clean... everything looked as i expected.  Did not see any holes or cracks or problems with diaphragm.... but i'll be danged if i am putting it back in).  crf250x petcock on order now. 

I know, i should have hooked it back up through the petcock and seen if that made the problem re-occur (but i didn't).

Note: i did take the carb apart before doing all that, but i made no changes, found no problems, put it back together.
Note 2: i am using 06' carb on an 01' bike, so i don't really expect it to work right... but will be pleased if it does.  Won't know until i get a new petcock.

You can bypass the petcock pretty quickly, just two allen bolts, and then plug 'main/on', and connect reserve to the one going to carb (but you'll be leaking gas while doing all that... caution tree huggers).  Or maybe just apply good vacuum to the vacuum port of petcock (ummm, use your mouth and suck ahhahahahah) and see if idle/rev improves.

Now i have backfiring through right side carb... off to the search function for me.

[gsdox]

all right again! It failed me once more!
I was out to test it and after 700-800 meters it started stumbling again. I turned around to take it home and after running on one cylinder, it completely died 100 meters from home. And guess what, now the engine won't start (with the newer ignition box, coils ad fuse installed) 

gs500e I don't think it's the petcock as I have swapped it (and the routing) with another one (from the crashed bike, so i guess I wouldn' t have the same problem with that one too).

The spark plug cables shouldn't be the thing as well, as i swapped the coils with the cables all together.

The fact that the bike did start when i messed around with its electronics, makes me think that it must be sth like xunedeinx said.
But does anyone have a clue where to look for at first? what connections are to blame for not starting, connections that have caused you trouble as well...
Thanks guys for all the input!

[xunedeinx]

Could the choke be stuck on? Choke cable lubed, throttle cable as well...

Is start going threw and cleaning all the connectors with a small wire brush, and checking them with a circuit tester to make sure their ok. Replace and solder/splice in new wireing where it appears damaged. Also replace all vac hoses and fittings and fuel hoses. Start with the cheap shaZam!.

[ben2go]

Just throwing this out there.The kill switch could be shorting out or possibly the side stand switch.My side stand is worn.Sometimes it can vibrate just right, let the switch release, and kill the engine.

[crzydood17]

do a oil change into a clean oil pan and run it through a coffee filter, MAKE SURE YOU REFILL IT, too many times i have seen someone start a engine without oil... If theres a large number of metal shavings filtered out, you might be SOL.

if thats good move on to the next step.

Can you turn the engine with the rear tire, does it feel very fluid and smooth or does it feel hard easy hard easy (turn it over in 4th or 5th if ya can)

pull the spark plugs and turn the engine again and see if it feels much different. also take pictures of the spark plugs.

it should be hard to turn then easy then hard that means its compressing something.

if theres no major issue yet then we need to start looking at fuel and spark.

pull out the ole DVOM (multi meter) and test your new coils (everything can fail never write something off in a diagnostic)

if the coils are good now the tricky part

unplug the coils from the ignition and unbolt your exhaust (don't fully take it off just undo the bolts that hold it in place to the head)
stick a peice of cardboard or something strong between the head and the exhaust and turn the engine over with the starter, the engine should not start if it even acts like its trying to fire you didn't unplug the ignition and can damage your valves.

after a few revolutions pull the divider out and there should be fuel on it. If not we have our general diagnosis and now you get to play with carbs...

This is just basic engine diagnosis from my mechanics background, if theres anything else more specific to GS's I don't know it yet.