Coil data interpretation

[Roemy24]

Checking the coils I'm getting 4.7 on the primary, which I understand is in spec. The secondary however I'm getting around 17K testing from inside plug ends between 1 & 4 and then 2 & 3.

After searching around I see that 20-30K is spec however my Clymers is saying about 32K. The other stranger thing is that when I'm reading the primary I get a constant reading. The secondary will flash a number and then disappear. I can only assume that I'm not making a great connection but opinions on this would be helpful also.

Should I be looking for new coils?

Thanks!

[twiggy2cents]

couple things ive realized, you get a better reading with no caps on the wires but there is no spec so you should test off of a known good one like that. Also ngk caps have a different resistance than stock also it is a good chance your not making good connection

[Roemy24]

So the test with the caps off is 12,500. I tried to measure across the cap but couldn't get readings. Now what do I need? Are the coils shot? Do I just need new caps?

[rustybronco]

reach into the plug cap with a small screw driver, remove the brass nut, remove and check the condition/value of the resistor.
if the resistor is found to be bad, substitute a length of brass rod, install it in place of the resistor and order a new cap.

[Roemy24]

Pulled them out and all look white, a little burned/charred on the ends. Some had metal round ends that fell off. I would assume this means they are all crap. What part numbers do I need or more specifically what resistance do they need when I go look for new ones? Thanks

[rustybronco]

5k is the value of the caps/resistors.
measure the length of a good resistor, cut a piece of brass rod to match, insert in place of the bad resistors, ride it while getting new plug caps.

***edit*** did you measure the resistance of the resistors?

[twiggy2cents]

i dont know your part number because they are different diameter than mine but they are ngk and look around i think their website shows you how to match them up, if not google it. Also you want 5K ones and they are only like 2 bucks a piece or something. When you do it snip off some of the spark plug wire(just enough to get too fresh wire) to give the new cap maximum contact. I think mine were 13K ohms or something so it sounds like you are okay on the coils

[Roemy24]

Refreshing to here that the coil readings seem ok. I don't understand though why 20-30K is spec and you can run good on just 12-13K.

[rustybronco]

refreshing to here that the coil readings seem ok. I don't understand though why 20-30k is spec and you can run good on just 12-13k.

12-13k + 5k + 5k=
12-13K + infinity + infinity= no run
12-13K + 0K + 0K= runs with noise on AM radio

the resistors are for noise suppression

[Roemy24]

Thanks for the equation. That means I'm running on the low end but still good. Any reason why the book would say approx. 32K required?

If anyone can help on the cap conversion, very much appreciated. Either my mind is fried, I want to ride, it's Friday or a comibination but am not understanding the NGK conversion chart.

10, 12, 14mm? Resists isn't listed, just that there is resistance. The angle is about the only thing I can figure out!

[twiggy2cents]

32K is the middle of the range. Also you have BR9ES? if so the B is your diameter look up your plug code for that. For reference mine are D9EA's and they are a different diameter then for the rest of the choices just mimic the ones that are on it. As far as the last one being weather tight or something, mine didnt have an option for that i just chose t he regular and it comes with the rubber pieces

[rustybronco]

Any reason why the book would say approx. 32K required?

Different scenario, 12-13k + 5k(cap) + 5k(cap) +5k(br8es resistor plug) + 5k(br8es resistor plug) =32-33K

b8es= no resistor
br8es=5k resistor in plug!!

***edit*** different, different scenario... substitute resistors with brass rod, buy four resistor plugs for it and don't order plug caps...

[Roemy24]

The book calls for B8ES plugs. Would it be wise to switch to a BR? That would put me right at 32K. Also, the resistor in the cap is always 5K? I don't see any number for resistance in the cap when looking on NGK.

[twiggy2cents]

its not a big deal ultimatly the spark is fighting infinite resistance 5k more on each wont hurt it. I run resistor plugs in mine. Although if your shop has them in stock get the non resistor. If not its not a big deal.

[reddirtrider]

As was stated earlier, the resistance in the plug caps is for noise suppression related to AM radio. Nobody listens to AM anyway unless they've tuned in to the loud mouths who discuss politics. My suggestion is to leave the resistors out and enjoy the ride.