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Bike runs but no readings from coil

  • Thread starter Thread starter smarzinski
  • Start date Start date
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smarzinski

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I have what I can only describe as a "sputter". When cruising the bike spits and sputters and recently No.4 cylinder keeps fouling out. I have replaced the wires, plugs and caps. I took one of the coils out just to take a reading and according to the service manual, I am supposed to have a reading of 3-5 ohms on the primary and 30-50 ohms on the secondary. I put the multi tester in and got NOTHING. Am I missing something? Tried searching and couldnt seem to find anything about sputtering or anything on my bike. Anyone have any Ideas or suggestions? Need to get this thing running asap.
 
Do you have the wires disconnected from the primary terminals?

If you don't, you may not see the correct readings.



For the secondary side resistance, read the book again, you should be seeing 30-50k ohms. That's THIRTY TO FIFTY THOUSAND ohms. :eek:

Measure that from one spark plug cap to the other.

.
 
Yea sorry guys I just realized I didnt put what bike. It is an 83 GS750E. Also I forgot the put the "k" in the 30-50. I took the entire coil out and disconnected it. I get zero all the way around.
 
Do you have OEM plug caps? Aftermarket caps may have about 5K less ohms on each cap meaning your reading of 25K might be all right if you have the aftermarkets.
 
No, Im using NGK caps (5ohm) I believe they are VD05F's. Going to check the other coil to see what its at and go from there.
 
took the caps off and measured directly from the wires and got 15k. Looks like Im looking at new coils. Anyone out there have any good suggestions????
 
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smarzinski said:
No, Im using NGK caps (5ohm) I believe they are VD05F's. Going to check the other coil to see what its at and go from there.
Click to expand...
Again, you are missing the K. Those caps are 5k ohms.


smarzinski said:
took the caps off and measured directly from the wires and got 15k. Looks like Im looking at new coils. Anyone out there have any good suggestions????
Click to expand...
In stock form, it is measured from plug cap to plug cap. The plug caps have 5k resistance, so if you include both of them, you would be reading 25k.


smarzinski said:
also, still no reading form the primary side on either coil....
Click to expand...
When you say "no reading", are you reading Zero (as in 'direct short') or OL (as in 'out of range' or 'open')?

.
 
My stock plug caps measure 11K ohms each approximately. If you include 2 of those plus your 15K ohms wire to wire measurement you would come up with 37K ohms. I don't think your 25K ohm measurement cap to cap with the NGK's is a problem.

On my coils, to measure primary, I have to make sure to get a real good contact with my cheapo meter. Are you sure you have the meter set in the proper range to measure ohms instead of K ohms?
 
Steve said:
When you say "no reading", are you reading Zero (as in 'direct short') or OL (as in 'out of range' or 'open')?

.
Click to expand...

When the multimeter is not connected to anything and turned on it reads "1". When I connect the contacts to the primary side of the coil it still reads "1". Tried every ohm setting and get the same thing.
 
1948man said:
My stock plug caps measure 11K ohms each approximately. If you include 2 of those plus your 15K ohms wire to wire measurement you would come up with 37K ohms. I don't think your 25K ohm measurement cap to cap with the NGK's is a problem.

On my coils, to measure primary, I have to make sure to get a real good contact with my cheapo meter. Are you sure you have the meter set in the proper range to measure ohms instead of K ohms?
Click to expand...

Got some new leads for the meter, got a reading of 4 ohms on the primary side. My caps tested to 5k ohms each and the coils without the caps tested at 15k ohms. If im understanding this thats only 25k ohms.
 
Sounds like you have NO PROBLEMS. Put it back together and RIDE IT.
action-smiley-083.gif


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smarzinski said:
Got some new leads for the meter, got a reading of 4 ohms on the primary side. My caps tested to 5k ohms each and the coils without the caps tested at 15k ohms. If im understanding this thats only 25k ohms.
Click to expand...

As noted, the coil itself is only about 15k ohms of the secondary impedance. In stock form, the caps are ~10k each or 35k total. With 5k caps (which are no problem), you're only going to be at 25k. Listen to Steve and ride!
 
mike_of_bbg said:
As noted, the coil itself is only about 15k ohms of the secondary impedance. In stock form, the caps are ~10k each or 35k total. With 5k caps (which are no problem), you're only going to be at 25k. Listen to Steve and ride!
Click to expand...

Ok, coils are going back on. Still have the sputtering though....Carb related? Also, just realized my whole train of thought was bass acwards. Sorry for the stupid questions.
 
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smarzinski said:
Ok, coils are going back on. Still have the sputtering though....Carb related?
Click to expand...

Might be; that would be my guess. While you're checking out the ignition though - have you checked your voltage at the coils? Checked your charging system health? It's sputtering at speed or only at idle? Are you stock and leak-free at the airbox and exhaust?
 
mike_of_bbg said:
Might be; that would be my guess. While you're checking out the ignition though - have you checked your voltage at the coils? Checked your charging system health? It's sputtering at speed or only at idle? Are you stock and leak-free at the airbox and exhaust?
Click to expand...

Checked the charging system when I replaced the R/R a couple months ago. Adjusted the valves, carbs were cleaned and synced, airbox was sealed. It sputters when I hold a steady speed, doesnt matter what speed. If I open up the throttle everything seems fine, but when I get back to speed it starts sputtering again. gotta run out and check the voltage at the coils this afternoon...
 
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