Weak spark no start on 81' Gs850G

[mrhedges]

I bought a running gs80g that had a leaky Carb. Had the Carbs rebuilt by someone on this forum that was recommended. Put them back in. It was hard to start the bike but it started then ran up to 6k rpms then back down. I was confused, then I slowly realized I hadn't seated the new airbox boots in right. I fixed that. Had trouble starting the bike again. Had some money issues so I didn't work on the bike for about a month. Now I can't get the bike to start. This is what I have done so far:

1. Tested compression. Got 120 PSI on each of the 4 cylinders

2. Tested the battery. It holds a charge of 12.56 V

3. Tested spark. I tested twice 1st time very weak yellow spark 2nd time very very faint yellow spark,

Gas flows from the the tank and the carb bowls are full and the sparks plugs aren't wet but smell like gas.

I figure that this is a electrical issue. The previous owner had the stator, battery and coils replaced. I figure the next step should be testing the spark plug wires, then the coils, then the CDI box. But how do I do that? What's the best way? Is there anything I am missing?

[fastbysuzuki]

The compression should be ok for it to run but your battery may be suspect have you run some tests to see how it holds up under load? If not look here it's post #1. http://www.thegsresources.com/_forum...tem-QUICK-TEST.

Also measure the voltage at the coils and post the results.

[tom203]

Test the ignition like this link....

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A17

remember apply full "choke" , but NO throttle when you crank it over. Make sure plug wires are on correct spark plugs.

[mrhedges]

thanks this is what I was looking for. If I have time tomorrow I will start to work through this list and report back

[Brendan W]

In the long run, methodical and thorough is best however in the case of ignition there is one short cut that is imho worth taking. Check the supply plugs to the coils. If the coils aren't getting proper supply all bets are off and many other tests will not yield meaningful results. The plugs might look good but hide corrosion of the wires just at the pins.

[mrhedges]

The plugs are new. I suspect that the previous owner had the coils replaced and I suspect the issue is old wiring or a bad igniter. I don't think I will have time to check these things until next week. I have to go to a wedding on Halloween and I need to make really good costume. Thinking Quint from Jaws.... kinda off topic. Thanks for your help!