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Help with carbs and coils

  • Thread starter Thread starter machine
  • Start date Start date
M

machine

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Whats up! After a hellacious quarter in school, i get to work on my ride. Unfortunately, its been sitting about 4-5 years so i had to rebuild the carbs - its a 79 GS550L BTW). My carb question is where does the vent hose go from the "uniquely vented" (right inner?) carb? The petcock? I know the other two just vent to the atmosphere. Now my coil question. Unplugging the two smaller wires, i took an ohm reading from both coils. The left coil pack read a few K ohms (checking each wire to a known ground) while the right side went right to 0 ohms right away on both wires indicating no resistance. This is with the plug wires connected and the coils mounted to the frame - checking each wire to a known ground (the block). I would think they would be the same. Niether side has spark, all fuses are good. Apparently, for umpteen years whatever hack that worked on it back in the day never bolted the coils back on the frame and just let them sit there. I was thinking they could fried from that. Thanks in advance for any advice!
 
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The center vacuum hose goes to the small fitting on your petcock
 
Coils should read approx 5 ohmn on the primary side (unplug the lead from the harness & check the resistance between the two wires feeding the coil)

The resistance on the secondary side should be approx 35K ohmns (measured from spark plug cap to cap).

If the primary resistance is not around 5 ohmn (OEM coil), then the coil is shot...

If your readings are screwy on the secondary side, unscrew the spark plug caps from each wire & snip off 1/4" or so to expose fresh, clean wire. Reattach the caps & check again.

It's a good idea to remove the caps & clean up the connection anyway - makes a big difference.

let us know how you make out

mike
 
resistance checks out good, where is the regulator at? the previous owner said he thought there might be a problem with it. Thanks!
 
How do you test a regulator? Where is it on the bike? Pardon my ignorance, I'm a FI guy. Pretty new to carbs and points ignitions.
 
Did you introduce yourself?

Did you introduce yourself?

Machine,

The best answer is that I think you never introduced yourself in the owners or GS forums. Not that there's anything wrong with that, but apparently you missed out on Cliffs mega welcome and website. Check it for a manual for your bike and the Stator Papers, your guide to the crappy GS charging system

Happy reading!

http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html

http://members.dslextreme.com/users/bikecliff
 
well, i am not sure if it has a stator or r/r problem, i can't get the POS started, There is no spark. I am trying to adjust the points, but as i said, i have no exp with them. what else do check after the coils?
 
I did, and again, I CAN'T GET THE THING STARTED. If I can't get it started, I can't do the tests the stator papers tell you to do at 5000 rpm and 2000 rpm, now can I? I don't know if it has a charging problem because it won't run. My question is on points, not the RR or stator. I imagine questions about the RR and stator will arise, but only after i get it running long enough to see if the RR and stators charging ability are questionable. After taking off the points cover, I found that one point contact gives ~12V (1-4 i think) while the contact for 2-3 gives nothing.
 
With the ignition key in the on position...

current goes to the coils. you should have at or near battery voltage showing. if you don't, you need to correct the low voltage condition before proceeding further. then current goes through the coil primary and on down to the connection where the points and condenser connect together.

when the point contacts are closed a magnetic field is formed in the ignition coil. when the point contacts open, the magnetic field collapses and induces the spark you see at the plug(s).

the path...
current goes... > to coil> through coil primary> to point set for 1-4 (or 2-3 depending on which coil you are measuring)> then "if" point is closed*> ground (earth).

point contact opens <BAM> spark is produced!

* you will only be able to measure voltage at the points, when the point contacts are open. otherwise, depending on the point condition, the voltage will be at or near Zero.
 
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ok. With the key in the on position, i have 10-11V to the Orange/white wires at the coils. I have about the same at the the point contacts at 1-4 when the contact is open. I don't get anything at 2-3 though, open or closed. the wire is good, i have continuity. Does this mean i have a bad coil? I am getting the same resistance at each coil primary and secondary sides though. This is getting frustrating!:mad:
 
machine said:
I don't get anything at 2-3 though, open or closed. the wire is good, i have continuity. Does this mean i have a bad coil? I am getting the same resistance at each coil primary and secondary sides though.
Click to expand...
A shorted to ground condenser would show zero volts. disconnect it and re-test.

machine said:
I am getting the same resistance at each coil primary and secondary sides though.
Click to expand...
The coils "should" be good...
 
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Ok, I disconnected the wires that from the coils to the points. Since power is constant to the O/W wires when the key is on, the wires at each coil that go to the points should have power, right? I only have power at one of them.
 
machine said:
Ok, I disconnected the wires that from the coils to the points. Since power is constant to the O/W wires when the key is on, the wires at each coil that go to the points should have power, right?
Click to expand...
Yes , if the wires are disconnected for the points you should have voltage on both wires. (or at the coils if you disconnected the wires from the coils.)
 
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with proper voltage going to the coil and nothing coming out of it, then yes the coil is suspect.

I thought you had the same resistance measurements on both coils?

(I'm leaving for home...)
 
i do which is wierd. i have about 10 ohms for each on the primary side
 
hikermikem said:
Coils should read approx 5 ohmn on the primary side (unplug the lead from the harness & check the resistance between the two wires feeding the coil)

If the primary resistance is not around 5 ohmn (OEM coil), then the coil is shot...
Click to expand...


machine said:
i do which is wierd. i have about 10 ohms for each on the primary side
Click to expand...

If you measure 10 ohms on the primary then the coil(s) shot...
 
actually, i take that back, i am getting 2.5-3.5 for each. (my ohmmeter was on the wrong setting).
 
what i did notice, was that the wires from the suspected bad coil were switched- the bullet connectors were spliced and flipped. when i try to hook up the orange/w from the coil to the incoming power (O/W), it blows a fuse. when the bike was running, it was hooked up with the switched wires.
 
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