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Random no spark/Weak spark!

  • Thread starter Thread starter Alekzandru221
  • Start date Start date
A

Alekzandru221

Guest
Hello! My name is Ruben.
I been a regular visitor on the forums! All this Threads have been super useful and helpful!
I finally decided to register and ask a question as I am stuck on this built.

I have a 77 gs750 that I'm building in to a cafe. Had it for about 8 months. Slow project and first bike build.
I bought this bike running but in really bad shape, Previous guy just got it running to sell it. Not mad, got it for $450 with clean tittle.
Started work on it.

So far I :

Re ringed pistons, new gaskets, new fluids, did frame work, did Seat, had to get pods (hate them) because previous owner lost air box, rebuild carbs, got re jetted (pain in the ...) Valve clearance adjusted, new ignition coils, new battery, rebuild petcock, fork seals, new brakes and rebuild calipers. Not in this order...

I got it running a few days ago, rode it and it would bug if opened to 1/2 throttle. Left it alone as I was waiting on bigger jets and didn't want to mess with the carbs. Jets came in, I re adjusted float height, changed to 117.5 mains and stock idle jets, lowed needle 2 notches. I got it back together, everything seemed ok. Tried cranking and it would not start. It would ignite but not catch. Removed spark plugs to check them and clear cylinders. No spark on coil for cylinder 1-4. So i checked ignition timing and it was a off, adjusted timing. Tested with light on point to make sure contact was breaking. Then...Random Weak intermittent spark on Coil for Cylinder 1-4...I checked the coil by changing the leads of coils 2-4 to it, and it worked! So both coils are good. Checked all connections, re did ignition timing, cleaned points. Everything good. but still weak spark on 1-4( Coil 2-4 have a beautiful thick blue spark)

Any ideas on what it could be? Points? Condensers? Ignitor?

This is my first motorcycle build. Have a lot of experience on bigger engines and decided to start expanding my knowledge and get into riding.
Thank in advance to everyone!
I will try and get some pics uploaded!
 
More then likely you have a bad connection on the 1-4 coil. Have you checked the voltage at the coil with the ignition on? Compare with voltage on the 2-3 coil. Should be within a volt of the batter voltage with the ignition on. Make those measurements and report back what you find. Could also be a week condenser. Personally I'd switch to electronic ignition and do away with the points and condenser altogether.
 
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I vote for bad condenser, just get new ones or test by switching them around now. Make sure wires down there aren't grounding out on plate ,etc.
 
Im going to test out condensers tonight and report back. As for the Self contained condensers, Would they work with stock coils/ignition, or will i have to get the dyna ignition coils and ignitor as well?
 
So got in new condensers and points! sparks like a brand new bike! Got it all put back together and tested it out, Turned on on first try!
Now I have a new issue, i can hear a loud noise coming from the engine, towards the center...I will check valve timing and make sure the chain tensioner is doing its job.
 
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