Need advice!!

[Guest]

Hi
I have a gs 750 from '78. The owner took the bike to pieces and renovated the mechanical part and the frame, fork, a.s.o. for about 5 years ago. Efter half year he bought another bike and the GS had been sitting since. I bought it last month and came home after a long drive, half while raining. The next day, I changed the spark plugs because it was driving a little sluggish, and took it for a ride. She was gliding smoothly but after 10 min I lost the blink on the left side. After another 10 min, I lost the right side too. After another 10 min, I was forced to stop at a light and put the bike in neutral. When I stopped and the bike reached idle rpm, it stopped. Tried to start the bike but nothing. I MEAN NOTHING. It was like i did not had any battery on. No sound from the motor starter, no nothing. The green light for gearcase and the red light for the oil pressure were on.

I tried to check the stator but it gives 0.000 all the way. No leakage of current. Ground ok.
I tried to check the rectifier/regulator. The difference is quit big, I think: 0.550/0.498/0.482
I changed some faulty cable shoes.
I recharged the battery.
I jumpstarted the bike.
I checked the plugs for spark(on the engine). Got spark from all of them.
I cleaned the spark plugs- they were a little black and 1 was actually a little wet.
Nothing. The best I got, was yesterday when I actually cleaned the spark plugs again, and with no choke, it actually started but as soon as i gave a little gas, the bike died. Tried again, started, waited to see what happens, after 10 seconds, the bike died.
I tried also with the kickstarter when the el-starter was making that grinding metal-ish sound and couldn't hear the sharp kick.
I am lost for words, and I honestly don't know what might be the problem.

Any thought on what might be the cause of it? My friend from whom I bought the bike said it was all original and never ever had any problems. And he actually said something about the ECU unit that times the spark plugs.
Any other thought before I get myself swamped in mc parts debt?

Thanks in advance for whomever might give a hand.
Regards
Silviu

[tom203]

You likely have charging issues, as in not charging!

"My friend from whom I bought the bike said it was all original and never ever had any problems. And he actually said something about the ECU unit "

If it's an original 78 gs750, it didn't have an ECU- just points and condensers: please check
Probably came with seperate rectifier and regulator, but maybe someone replaced it with a combo r/r: check

which spark plug was "wet" ? #1 is under the clutch lever,with #4 under the front brake lever

[azr]

I wonder if your points got wet from the ride? they should have dried out over night but it sounds like the bike needs a good going over. Check the points and do the timing. Test your charging system to make sure it's all working properly. Brakes, etc..etc..

[Silviu Andrei]

ECU was installed later on. rectifier is separate from the regulator(under the battery case). it was number 1 actually. I know it's not charging but I cant put my finger on if it or not the stator.

My friend said that he bets his pony tail on the rectifier. But as I read her on the forum, I came across a thread on a ignition problem that resembled mine, so I found out that there could also be the igniter...considering that it dies while accelerating(flooding of the chamber while the spark is not strong or missing =>wrong timing=>ECU??? )

You likely have charging issues, as in not charging!

"My friend from whom I bought the bike said it was all original and never ever had any problems. And he actually said something about the ECU unit "

If it's an original 78 gs750, it didn't have an ECU- just points and condensers: please check
Probably came with seperate rectifier and regulator, but maybe someone replaced it with a combo r/r: check

which spark plug was "wet" ? #1 is under the clutch lever,with #4 under the front brake lever

[Silviu Andrei]

The spark got wet while trying to start the bike...Not right after it stopped the first time. Because I cant start the bike, I can't check if it's starting.
I bought a battery charger and charged the battery over night. The moment I put the battery on the bike, it tries to start and after 1 min, it acts like it's empty.
I also tried the kickstarter. Nothing. Not one time that it worked. Even though sometimes it gave the impression that its gonna spin.
Can it be a mechanical problem that inhibits the electrical system?

[azr]

I wasn't referring too the spark plugs, I was talking about your points being wet. Check to make sure your points are in good condition and set properly. Test your charging, that will rule out a couple of things to begin with. As well check your connections, battery, harness plugs, etc.. a loose connection could cause some of these symptoms.