750 won't start (sorry, sort of long)

[donasmello]

I have a 78' 750GS and am having problems getting it to start. I have been working on it a lot and when i first got it, the bike would only start when it was cold..then stopped starting all together. Also the lights would stay on all the time without key in ignition. So here's everything I replaced in guessing what was wrong from research so far:
-wiring harness (used)
-starter relay
-starter (used)
-battery
-coils (3 ohm green)
-spark plug wires
-only fuse
-bike had dyna ignition from PO
I let it sit for a week after putting wiring harness in, reattached gas tank, wouldn't start. Sprayed starter fluid in carbs, and started right up and drove it around for about 2 seconds and seemed alright. The carbs are definitely not synched though. Then I shut off, fixed all the wiring so it was covered and wasn't hanging, and of course it doesn't start after that. It seems to be getting spark, although yesterday it was kind of intermittent. Battery was fully charged when trying, but the starter seemed kind of weak, but I also have a kick starter that I have been using and still nothing. The electric starter would seem to catch sometimes, but I would have to pull the throttle all the way open to get 2K rpms. Petcock seems to be flowing well when gas tank is not attached also. The PO said he had rebuilt the top end, rebuilt carbs, and advanced timing. I have had this bike for a month and have rode it two times and have been trying to fix it the rest of the time. PLEASE HELP!!!

[rgierer]

First...let me say...I know that pain.

The tough part here is that you have a lot of stuff on the table at one time.

The early 750 is an amazing bike that will bring you lots of good times. the effort is worth it. Once you get it dialed in it is a remarkably dependable horse.

I am of the inclination to reccomend a couple of things.

1 check your main fuse connections. I have a 78 550 which will often had problems with the electric starter only to find the main fuse had a weak connection.

Now for something more basic. check your spark. How is it at the plugs? You should get plenty of spark there.

If thespark is less than really strong I am going to send you back to check connections on the wiring harness. IMHO, these wiring harnesses were not great when new and call for extra care in there dotage.

After you go through the wiring check the plug again and see what you find.

[nabrams]

You said the lights were staying on even with the key out? Well, you've definitely got a short there, at least. Now, even if that problem has been resolved, you need to verify there are no shorts anywhere else. Your intermittent spark sounds like an igntion component on the way out. To eliminate a possible weak battery from the equation, jump from your car battery (car NOT running). All of these topics have been discussed in-depth in other posts - do a search. You will need to become VERY familiar with your bike's wiring diagram and the usage of a multi-meter. If you're not "electrics-savvy", now is the time to become savvy.

[donasmello]

sorry for not replying for so long, but I have not had internet for like the past week. I actually got it started though!!! It turned out to be the spark plugs. They had severe carbon fouling so I went and changed them out and voila! I hadn't checked those yet just because I took the PO's word for it that he had just replaced them. Just need to synch the carbs now and I'll be set I think. Thanks for the help!