1980 GS1000G - Won't start

[free99]

Hello everyone,
I've been focusing on getting my new/old machine running. However, she won't start.

Following's done:

1. She holds clean T6 15w-40 oil
2. I took apart the carbs and cleaned each one separately, replacing O-rings per cycleorings
3. Set float depth, bench synced the carb butterflies
4. New Intake boots and O-rings, cinched to a clean engine surface
5. Checked vacuum ports are tightly sealed, as are intake hose clamps
6. Valve clearances on cold engine are in spec
7. Checked plugs are sparking by laying them against the engine while cranking
8. Timing marks and timing chain line up, 20 links between 2 & 3
9. Checked pickup resistance, 340 ohms
10. Checked coil inputs while disconnected, each was between 4-5 ohms

The airbox is way more damaged than I'd originally thought. Shouldn't the bike still be able to start if I leave the airbox off? I also noticed that the bike tries to pull about 2A from the battery even while idle. I suspect something's funny with the igniter, what do you think?

 

[Brendan W]

By idle do you mean ignition on motor stopped?
Are the coils wired up right and left.
The plug with the white trigger wire is for the left coil for 1&4
The plug with the black/yellow trigger is for 2&3.
Should start with the box off.

 

[Steve]

By idle do you mean ignition on motor stopped?

What we call "idle", you call "tickover". Engine is running at its lowest speed.


Comments inserted.

Following's done:

1. She holds clean T6 15w-40 oil
2. I took apart the carbs and cleaned each one separately, replacing O-rings per cycleorings
   How did you "clean"? Did you remove all jets, slide, etc. and soak the body for 24 hours?
3. Set float depth, bench synced the carb butterflies
   Did you check both sides of the floats?
4. New Intake boots and O-rings, cinched to a clean engine surface
5. Checked vacuum ports are tightly sealed, as are intake hose clamps
   There is only one "vacuum port", it runs from carb #2 to the petcock.
6. Valve clearances on cold engine are in spec
   Were the cams in the correct positions? Pictures are confusing, text gives good instruction.
7. Checked plugs are sparking by laying them against the engine while cranking
8. Timing marks and timing chain line up, 20 links between 2 & 3
   Count PINS, not LINKS. PIN #1 should be above mark #2, PIN #20 should be above mark #3. That puts 18 links BETWEEN #2 and #3.
9. Checked pickup resistance, 340 ohms
10. Checked coil inputs while disconnected, each was between 4-5 ohms

The airbox is way more damaged than I'd originally thought. Shouldn't the bike still be able to start if I leave the airbox off?
Yes, it will start and idle, but probably won't respond to any throttle input. If you stretch a shop rag over the carb openings, it helps a LOT.
I also noticed that the bike tries to pull about 2A from the battery even while idle. I suspect something's funny with the igniter, what do you think?
When you say "idle" here, do you mean with key ON or OFF? I ask because it's obviously not with engine running, because of the previous questions. If the key is ON, some current draw is normal, but 2 amps is a bit low. If the key is OFF, you have a short somewhere, it needs to be found.

.

 

[Brendan W]

What we call "idle", you call "tickover". Engine is running at its lowest speed.
.

Oh we call it idle as well, that's the problem

 

[free99]

I'm sorry fellas, I wrote the first post about 20 minutes before hitting the hay, wasn't careful with my terminology.

When I say idle, I meant the bike was powered ("key on"), but not running.
Steve, in order:

• Yes, all carb parts removed and ultrasonically cleaned+blasted with canned air
• No, not both sides. Easy enough to do though. To double-check, what float depth should an 80 GS1000G need?
• Vac port on master carb (#3) is completely plugged, petcock was replaced by PO to delete vacuum control of fuel
• Cam lobes were correctly positioned per the guide on bwringer's site for 8 valve GS'
• Hmm... I'll count again later today, it was 20 pins I believe. Both 2 & 3 imprints were perpendicular to the head.

It should be 18 pins, shouldn't it. I'm also curious about the 2A draw while not running. The original harness is destroyed, I made an extremely simple harness only powering coils, starter relay & igniter, plus the required signal cables between pickup, igniter and coils. No R/R, no lights, nada. Just the absolute basics, all with fresh wire. I disconnect, then recharge the battery at night using an external charger after I finish my attempts for the day.

Brendan, I checked that the coil order is correct, B/Y goes to plugs for 2 & 3.

Thank you for your help, both

 

[Nessism]

I wouldn't bother measuring the floats again. Instead, measure fuel level. It's easy to make a tool (info available in the carb rebuild tutorial linked in my signature.) Adjust fuel level with a clear tube gauge, this will have the added benefit of showing you have fuel in the bowls.

 

[Steve]

I'm sorry fellas, I wrote the first post about 20 minutes before hitting the hay, wasn't careful with my terminology.

When I say idle, I meant the bike was powered ("key on"), but not running.
That puts a different spin on things.

Steve, in order:

• Yes, all carb parts removed and ultrasonically cleaned+blasted with canned air
  I don't have enough experience with ultrasonic cleaning to know how effective it is. Many claim it's good, I don't know for sure.
  
  
• No, not both sides. Easy enough to do though. To double-check, what float depth should an 80 GS1000G need?
  22.4mm ?1.0mm. I like to keep the two sides within 0.5mm of each other. The one with the higher number will determine the fuel level.
  
  
• Vac port on master carb (#3) is completely plugged, petcock was replaced by PO to delete vacuum control of fuel
  Either you have non-standard carbs, have arranged them differently in the rack, or are simply numbering them incorrectly. The carbs (and everything else on the bike) are referenced left-to-right AS YOU ARE SITTING ON THE BIKE. #1 carb is under your clutch hand, #4 carb is under your throttle hand. The vacuum port is on #2 carb.
  
  
• Cam lobes were correctly positioned per the guide on bwringer's site for 8 valve GS'
  I have not looked at that guide recently enough to remember what it says, but the proper way is to get both cam lobes on that side of that cam pointing away from their valves at about a 45? angle, then measure BOTH clearances. Rotate the crank 180?, check the next pair, repeat as necessary. If you pointed the lobe away from each valve, you got some wrong clearance readings.
  
  
• Hmm... I'll count again later today, it was 20 pins I believe. Both 2 & 3 imprints were perpendicular to the head.
  This detail caught me a few times, it's easy to mess up. When you are counting pins, do NOT start with the pin that is NEXT TO the arrow for #2 mark on the cam. Start with the pin that is ON the arrow and call it PIN 1. The #20 pin will be directly over the #3 mark on the intake cam. In other words, do not call the pin over the #2 mark "ZERO", then start counting.

It should be 18 pins, shouldn't it. I'm also curious about the 2A draw while not running.
Is the key ON or OFF? As mentioned earlier, if the key is OFF, you have a problem. If the key is ON, there is current flowing through the coils and ignitor. I would expect more like 4 or 5 amps, though.

The original harness is destroyed, I made an extremely simple harness only powering coils, starter relay & igniter, plus the required signal cables between pickup, igniter and coils. No R/R, no lights, nada.
Lights aren't "basic"???

Just the absolute basics, all with fresh wire. I disconnect, then recharge the battery at night using an external charger after I finish my attempts for the day.
Hopefully your wiring will change by the time you decide to ride it farther than your garage door.

Brendan, I checked that the coil order is correct, B/Y goes to plugs for 2 & 3.

Thank you for your help, both

I wouldn't bother measuring the floats again. Instead, measure fuel level. It's easy to make a tool (info available in the carb rebuild tutorial linked in my signature.) Adjust fuel level with a clear tube gauge, this will have the added benefit of showing you have fuel in the bowls.

One of these days, I'm going to make one of these. Actually, I'll probably make four, so they can all be checked at the same time.

.

 

[salty_monk]

Don’t give up... have you checked voltage drop on your new wiring? The ignition switch and fuse box are too big sources of losing volts....

 

[free99]

Hey Salty_monk, thanks for the encouragement. Came here to tell Steve and Ed and Brendan thanks, that it looked like the problem was with fuel height.

Idles rougher than a sandy condom, and dies if I apply any gas at all, but she runs. Now I gotta get to work on getting the tune right with my colortune, and a DIY synch. Then rebuild brakes, suspension, etc etc.

But, she runs

 

[salty_monk]

The dying when you apply gas would suggest plugged up carbs or air leaks still... Did you replace the intake boot O rings? Usually once they start they will run reasonably well if they are anywhere near close. What are your air correctors set at?

Of course if you still have the airbox off... that would totally explain it