No spark on any cylinder

[1983lux]

Hey all,

Working on Resurrecting at 79 GS1000E. After cleaning up the inside of the ignition switch and wiggling the fuses around, i managed to get the oil/neutral light to come on and the bike will turn over. However, it would not start. I removed a plug and when inserting the loose plug in each spark plug wire end, I see no spark at the gap for any of the 4 plug wires. What are some things to check?

Also, when I added fuel via an external fuel supply (tank will need work), it started dripping out the bottom of the carbs somewhere after a bit. I assume this is stuck floats/dirty needles not shutting off the supply of fuel so carbs are overflowing?

Thanks for any help.

 

[Big T]

Does it still have points?

 

[1983lux]

Hmm, haven't checked! I'll have to pop the cover off and have a look to see whether its original points or if someone put in a Dyna-type ignition.

 

[rphillips]

Just to be sure, you are grounding the base of the plugs against a medal surface while checking, plug wire just plugged to spark plug won't make a spark unless it's grounded.

 

[pdqford]

Hey all,

Working on Resurrecting at 79 GS1000E. After cleaning up the inside of the ignition switch and wiggling the fuses around, i managed to get the oil/neutral light to come on and the bike will turn over. However, it would not start. I removed a plug and when inserting the loose plug in each spark plug wire end, I see no spark at the gap for any of the 4 plug wires. What are some things to check?.

Plus one on rphillips.

And does the battery have enough voltage to run the starter AND the ignition?

(Easy stuff first.)

 

[Redman]

Check voltage at the coils (the org/wht circuit).

More specifically:
Check battery voltage with key off, and with key on.
Check voltage at coils with key on.
Check voltage at coils when cranking starter.
Report here.

 

[1983lux]

Hey guys,

Sorry it took me so long to check on things, haven't had much time for the bike lately.

Popped the cover and the bike still has the original points ignition.

I was grounding the plug, but maybe not the right way. The threads should be touching the outside of the engine block while I'm turning it over in order to see a spark I guess?

Here's the volt readings on the battery and orange/wht wire going to one of the coils:

Battery with key off - 12.98 volts (battery is only a few weeks old and is on tender when I'm not there)
Battery with key on - 12.47 volts
Org/wht coil wire with key on - 10.92 volts
Org/wht coil wire while turning the engine over - 8.67 volts

Do those readings look normal?

Thanks!

 

[Redman]

.
.
.
Org/wht coil wire with key on - 10.92 volts
Org/wht coil wire while turning the engine over - 8.67 volts

Do those readings look normal?
.

Nope.

Too low of voltage at coils for the ignition to operate.
If you want to conduct a test to prove it to yourself, run a temporary jumper wire from battery+ (or main, or aux) to the coils, and see if get spark then.
Note: THis is pretty much what the "Coil relay mod" does for you, but does it only when key is on.

The real fix is to find where are loosing the voltage, and fix that. Maybe the problem is at/in the ignition swtich, maybe in the fuse block, but probably in the wiring from the main fuse to the ignition switch, and probably some at all of the above and that all adds up to the about 2 volt drop from battery to the coils. THe additional one volt droop when cranking starter is related to strength of battery, and isnt too bad, but when already loosing two volts due to voltage drop.......

 

[Guest]

I'd say you are working on my 82 450a
I have the same issue so may jumper from the solonoid direct to the coils (orange / white) Though your voltage drop is quite a bit less than mine
13.08 at battery
Mid 10s at coils (no crank)
Mid 8's at coils cranking.
Though I don't have points.

Good luck on yours and let us know what you find out.

Alt

 

[1983lux]

Sorry to revive an old thread, but finally got around to working on the bike again. Bad voltage was fixed by some good cleaning of the wiring harness. However, the real culprit was that the points plate was cracked and grounding out! An amazon electric ignition fixed the issue and bike now runs! However, time to rebuild those badly leaking carbs. Drained oil and it was mixed with a lot of fuel, glad I didn't run the bike for long!

 

[rphillips]

Be sure to check the pet cock, From what I've seen from GS's, the vacuum petcock is more often the cause of gas in oil than the carbs... Just my opinion.

 

[1983lux]

Ah good to know, thanks for the tip! I noticed the gas tank on my bike is not from 1979, and someone has relocated the petcock further back on the tank. The existing one leaks, was put on with some kind of gasket goop. Amazon sells some pretty cheap replacements so I'll go ahead and get one.

 

[rphillips]

"80" GS1000's had CV carbs, their tops were much larger than the "79" VM's. Suzuki moved the petcock appx. 1 1/2 " back so it wouldn't hit the bigger carb tops. Also the "80" pet cock were totally different, I'm not sure if the bolt spacing is the same for both models or not. Surely somebody here knows for sure.

 

[Grimly]

"80" GS1000's had CV carbs, their tops were much larger than the "79" VM's. Suzuki moved the petcock appx. 1 1/2 " back so it wouldn't hit the bigger carb tops. Also the "80" pet cock were totally different, I'm not sure if the bolt spacing is the same for both models or not. Surely somebody here knows for sure.

Iirc, the oddball petcock (with the screw-slot selector) has a hole spacing of 50mm.

 

[1983lux]

​Here's a pic of what I've got going on with the tank that came with the bike. you can see the plate covering up where the petcock (originally?) went, and the one that's on it now further back.

 

[rphillips]

OOoohhh, not sure what's going on there. That tank sure looks like from an "80" or "81" either GS750 or 1100, certainly not a "79" GS1000 tank..

 

[Guest]

My crank filled with gas due to the vacuum petcock. I wrote a thread on this under fuel.
Although I replaced mine with another vacuum petcock, I really hate them all and would rather get one with RES OFF MAIN only which I prefer.
My issue is fixed... I think, but I don't trust it. If it ever comes back, Off with it's head and a non-vacuum one to be installed.

I put on this one
https://www.amazon.com/gp/product/B09NZVQTC9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


Alt.