don't know what's wrong with my bike

[muskies666]

the other day i rode my 79 gs750 to work. it was cold and wet in the morning so it was a little hesitant to start up, but once it did it ran fine. once i got to the shop, i let it idle for about five minutes and it sounded fine, then i turned it off and went to work. when i came out to go home it took about six kicks to get it started(it usually starts first kick when its warm outside). then it wouldn't idle without the choke all the way out and i could feel/hear a knocking in the engine. then it backfired once so i killed it. another guy there said it was smoking out of the exhaust which it usually doesn't. after i killed it, the battery was completely dead. don't know much about bikes due to this being my first one. any suggestions on where to start to get it running again would be a big help. thanks.

i've been told it could just be the battery, or possibly a broken timing chain. no idea.

[bonanzadave]

Do the easy (cheap) stuff first. If it dont like to run in damp wet weather change the spark plug caps.

[spyug]

OK lets not jump the gun here. Its not a timing chain or there would be a hellacious grinding noise and no fire in the hole ( i.e. no idling or running at all).

We need to get the engine turning again to do some testing but it should be done by hand. Get the bike on a lift or its center stand. Remove the right hand circular cover plate. With the engine in neutral, get a wrench the size of the nut and turn it slowly clockwise. It should turn freely and with no clanking or grinding noises. If you hear noises try to isolate where they are coming from. Get an auto motive stethoscope or use a long shaft screw driver. Have an assistant slowly rotate the engine and place the screw driver on the engine and rest your ear against the handle.

If you detect any strange noises or the engine binds STOP

If you do suspect the timing chain, cams or valves, you will need to remove the tank and valve cover for deeper investigation. A busted chain will be self evident. A dropped valve might not be so readily noticeable and you will need to look at diagrams in the manual ( to familiarize yourself with the parts and their fitment) and perhaps remove the cams and valve buckets ( I think your engine has them).

Before attempting to start the engine again you will need to isolate that noise and determine if the engine turns freely or not.

I don't want to speculate on it so please do some testing and report in with finds so we can determine what to do next.

Don't panic at this point but lets investigate a bit more.

Thinking good thoughts for you.
Cheers,
Spyug.

[SqDancerLynn1]

Sounds like a dead battery!!!! Kick it over easy with the ign off. RE charge the battery & try again, check the electrical system

[chef1366]

Sounds like a dead battery!!!! Kick it over easy with the ign off. RE charge the battery & try again, check the electrical system

Ditto!!!!!!!!!

[muskies666]

would a dead battery cause the knocking in the engine? it wasnt knocking like valve knocking it was quite a bit heavier. anyways im going to get a gel battery for it today and see what happens. thanks.

[robertbarr]

You already know what 'normal' feels like when you kick start the bike. Leave the ignition off, and kick a few times. Feel normal? Sound normal? Kick it once slowly. If you feel compression, it's not the timing chain. You should hear wheezes, like an emphysemic trying to breathe.

Where's the oil level? Something changed while it sat; perhaps you experienced partial hydraulic lock. If the oil level is REALLY high, and stinks like fuel, you've found part of your problem. How much more is FUBAR'ed depends on luck.

[Dave8338]

Dead/dying battery won't have the juice to fire the coils correctly and will give you a very weak spark at best and eventually, none at all. This may explain the smoke (unburned fuel with a loaded cylinder) and sure would explain the eventual no-start condition. Once you get it running...do yourself a favor and check the voltage (see stator papers) and ensure that you're not going to cook your new gel battery.

[muskies666]

i just charged my old battery and cleaned the terminals and whatnot. she seems to be screaming again. i got the gel battery, but im trying to figure out how to mount it under my seat pan. been 2 days now and my battery is still charged, so i dont know why it went dead in the first place.

[skidMarkNZ]

i just charged my old battery and cleaned the terminals and whatnot. she seems to be screaming again. i got the gel battery, but im trying to figure out how to mount it under my seat pan. been 2 days now and my battery is still charged, so i dont know why it went dead in the first place.

Pixies, sneaky little buggers get everywhere.