lower resistance coils ok????

[Anonymous]

Hi guys , me again. I am going to try to use the coils from another bike on my GS550ES. with my meter (probably not quite correct), my stock coils measure about 4.5 ohms. the new coils measure 3.5, 1 ohm less.
I know that the DYNA coils recomended for this app. are 3 ohm coils, but like I said my meter is suspect and I do not know if 3.5 is the ACTUAL resistance. all I can tell is that the new 1s are 1 ohm less. is it safe to use coils with less resistance? I have heard horror stories of burned up ignitors and signal generators, but I can't remember the exact circumstance (higher or lower resistance). I am looking for reassurance that these are not in my future. if this works we will all have another weapon in the fight against hi-priced replacement parts. Thanks People. You are all truly a god send. :wink:

Pete

 

[Anonymous]

measure the primary and secondary resistance in each coil and maybe that will give one of us a clue--are the replacement coils stock coils or are the dyna coils---green brown--black?? get someone else to measure the resistance on a better meter maybe???

 

[Anonymous]

the coils are from a CBR600F3 and how do you measure the secondary resistance. Is that the Hi tension wire resistance? (plug lead) and is there a way to tell which primary wire lead is for the positive and which is negative. these coils are not marked like the GS. but they do have pigtails with wires. each have a black wire with a white tracer and then 1 has a yellow with blue tracer, and the other has a blue with a yellow tracer. About my meter. It seams to work properly to measure voltage and everything else but some1 told me that since I got the same figure for every GS coil in my garage including my brothers running bike that the reading must be off- (I am guessing due to 3 ohm coils being the norm with the GSs- acording to DYNA) I haven't been able to find out what resistance value any1 else has gotten from thier bikes. For all I know 4.5 is the actual resistance of the stockers and Dyna just recomends the 3 ohm ones. In which case I am fine to install these correct?

 

[Anonymous]

you have lost me on this one 8O

 

[earlfor]

Re: lower resistance coils ok????

Well lemme see, maybe this'll help...The basic way to check if you can use 3 ohm coils is to turn the key ignition to "on" and check for power to the coils. Do not hit the starter button during this
procedure. If there is power present then you can use the coils. Common power wire Make=colors/stripes. Honda=Black/White
Kawasaki=Yellow/Red Suzuki=Orange/White Yamaha= red/ white Conversly, if no power is present, you need to use the stock 5 ohm coils.

Earl

Hi guys , me again. I am going to try to use the coils from another bike on my GS550ES. with my meter (probably not quite correct), my stock coils measure about 4.5 ohms. the new coils measure 3.5, 1 ohm less.
I know that the DYNA coils recomended for this app. are 3 ohm coils, but like I said my meter is suspect and I do not know if 3.5 is the ACTUAL resistance. all I can tell is that the new 1s are 1 ohm less. is it safe to use coils with less resistance? I have heard horror stories of burned up ignitors and signal generators, but I can't remember the exact circumstance (higher or lower resistance). I am looking for reassurance that these are not in my future. if this works we will all have another weapon in the fight against hi-priced replacement parts. Thanks People. You are all truly a god send. :wink:

Pete

 

[Anonymous]

Earl
I honestly cant see what the resistance of the primary side of the coils has to do with whether or not you get a voltage reading to the coils--if you put a set of coils in the circut with a million ohms resistance on the primary side you should still get a voltage reading--i am surely missing something in your explanation --please help to clarify my understanding of your posting

 

[kz]

Hi Karsh,

Where are two kinds of resistance in a coil...

One is for DC-current i.e the bike is not running and the ignition is on, this is the value you are meassuring with your Ohm-meter.

This is what Earlfor probably want you to test.

The other "Omh" resistance (even called Z impedance at least in Swedish) is dependent of the frecency i.e engine revs and is related to the wire turns inside of the coil and not to the lead diameter/lenght.

This means that it is possible to use a coil that works fine during running, but if you leave the bike with the ignition on without running you can burn the coil.

The soulution in this case, is to mount a resistor in serie with the coil, beacuse the resistor only decrease the current when the bike is not running.

 

[kz]

Hi Slowpoke,

If the resistance is to "low", the Voltage-reading probably will drop, and if it is very low you will have almost a short-circuit and very low Voltage-reading (depending of the battery-size of course).

On the other hand if you have "a million ohms you will not have any voltage-drop.

 

[Anonymous]

8O Things are starting to get hazy now. How about this: could any of you running factory electronic ignition unplug a coil (the two little wire connectors at the front) and test the resistance between these two little metal tabs on the coil (that the little wires plug on to) and tell me what resistance figure you come up with??? Maybe I will post this as a new topic also.

Pete

 

[Anonymous]

Hi Slowpoke,

If the resistance is to "low", the Voltage-reading probably will drop, and if it is very low you will have almost a short-circuit and very low Voltage-reading (depending of the battery-size of course).

On the other hand if you have "a million ohms you will not have any voltage-drop.

the resistance has nothing to do ith the voltage drop unless there is resistance in series .once a lozd is placed in a circuit, the current will flow according to ohms law- if the resistances is too low the item will burn out--none of the things tou are talking about apply here any how-

 

[Anonymous]

kz is right, but testing coils (by the manual) means just measuring their DC-resistance.
If you get readings between 3 and 5 ohms, you're fine.
I see no reason why you should not use the Honda coils, if their resistance is between 3 and 5 ohms.

Jojo

 

[Anonymous]

kz is right, but testing coils (by the manual) means just measuring their DC-resistance.
If you get readings between 3 and 5 ohms, you're fine.
I see no reason why you should not use the Honda coils, if their resistance is between 3 and 5 ohms.

Jojo

ok JO JO
now i wil ask for your help. please explain to me how the voltage will drop if the resistance is too low and we are still talking about the primary side of an ignition coil i think??

 

[earlfor]

Well Scotty, my post is the common answer you will get if you call Dyna, your local dealer or most any supplier with this question:
"I want to change coils on my motorcycle and I want to know if I need to use 3 ohm coils or 5 Ohm coils" I make no claim to being an electrical engineer, so I can only say I suspect that using the wrong coil probably would result in burning out the coil. I have no idea how quickly it would burn out though. I believe Karl is correct in his accessment of the situation, but again ...I dont claim being an elec wizard. Also, to use a 3 ohm coil, the ignition on, power present means you may use a 3 ohm coil. Nothing is said about resistances, only that power is present. The method does work.
For those that wish to debate electrical theory, please DO, I find it interesting reading. REALLY

Earl

Earl
I honestly cant see what the resistance of the primary side of the coils has to do with whether or not you get a voltage reading to the coils--if you put a set of coils in the circut with a million ohms resistance on the primary side you should still get a voltage reading--i am surely missing something in your explanation --please help to clarify my understanding of your posting

 

[Anonymous]

Earl
Please tell me what you mean when you say power???

 

[earlfor]

Scotty

I meant that the circuit is hot, ....active. A coil may be powered up when the ignition is turned on, or it may be powered up only when the engine crankshaft is rotating.

Earl

Earl
Please tell me what you mean when you say power???

 

[Anonymous]

Here we go:

power = voltage times current

current = voltage devided by resistance

This means: if your coil resistance = 3 Ohms and your voltage is 12 volts, the current through your coils is 4 Amps. (12/3=4)

Now, if the current is 4 Amps, the power through your coils is 12 x 4 = 48 watts.

Now, suppose your coil resistance is 5 ohms: what would happen?
Voltage is still 12 volts, so the current through the coil would be 12/5=2.4 amps.

Are you still with me?

The power through the coil (actually called dissipation) is 2.4x12=28.8 Watts.

This means thet using a higher resistance coil results in less primary current, resulting in a weaker spark. If you use a coil with lower primary resistance, you'll get a stronger spark on the secondary side.
If the primary resistance gets too low, it will depend on the capacity of your ignition system, whether it survives or not. Better keep within specs.

Having said this, just a note on bad connections:
If your coil wires have corroded connections, with a resistance of, let's say, one Ohm (whitch is very low!), this means that with a current of 4 amps, you'll get a 4 volts voltage loss. This means, that there's only 8 volts left to feed the coil. Resulting in a 30 percent weaker spark....

Keep your connections clean!

Jojo

 

[Anonymous]

Scotty

I meant that the circuit is hot, ....active. A coil may be powered up when the ignition is turned on, or it may be powered up only when the engine crankshaft is rotating.

Earl

Earl
Please tell me what you mean when you say power???

OK Earl
I am wondering if you ever actually did the test that dyna recomendes and ill tell you my reason for asking-
If the ignition is on and the crank is not moving then the ignition mechanism under the side cover is not moving--if nothing is moving whether points or magnets then no signal is being sent to the ignitor box---if no signal is being sent to the ignitor box then the coils shoild not be firing----whenever there is voltage on the primary side of the coil, then current will flow and induce the secondary voltage--when the secondary voltage is induced then the plug will fire because it is always grounded---NOW--if the primary side of the coil is hot as soon as the ignition is turned on then the coil will fire continuously--and if the test is valid for both coils then all four plugs start to continuously fire as soon as the ignition switch is turned on---this is what didnt compute and i am wondering if the information is incorrect or i have something backwards in the manner that an ignition system operates???

 

[earlfor]

[quote="SLOWPOKE"
OK Earl
I am wondering if you ever actually did the test that dyna recomendes and ill tell you my reason for asking-

(yes, I have done that test and just to give you some numbers, my voltage at the battery terminals is 11.9. With the ignition on, the voltage to the coils is 11.8 No, the plugs are not firing continuously or otherwise....


If the ignition is on and the crank is not moving then the ignition mechanism under the side cover is not moving--if nothing is moving whether points or magnets then no signal is being sent to the ignitor box---if no signal is being sent to the ignitor box then the coils shoild not be firing

(I agree with the above)



----whenever there is voltage on the primary side of the coil, then current will flow and induce the secondary voltage--when the secondary voltage is induced then the plug will fire because it is always grounded---NOW--if the primary side of the coil is hot as soon as the ignition is turned on then the coil will fire continuously--and if the test is valid for both coils then all four plugs start to continuously fire as soon as the ignition switch is turned on---this is what didnt compute and i am wondering if the information is incorrect or i have something backwards in the manner that an ignition system operates???[/quote]

(nope, the coils will discharge and fire the plugs only when triggered by the ignition timing. In 360 deg of crankshaft rotation, there are only two points at which the circuit is complete and the plugs can fire)

Earl

 

[Anonymous]

thanks for replying Earl
do you know where the circuit is completed to make the plugs fire--is the ignitor box then completing the circuit on the secondary winding of the coil

 

[earlfor]

Yep Scotty, thats really all an ignition system does is control the point at which the coils discharge and fire the plugs. It doesnt really matter whether its a breaker point system or an electronic/optical system, its nothing more than a timer.

Earl

thanks for replying Earl
do you know where the circuit is completed to make the plugs fire--is the ignitor box then completing the circuit on the secondary winding of the coil