Hello,

Bike is a '87 Softail, stock, with Dyna S single fire and mechanical advance unit.
Currently I run Champion spark plugs, but everybody tells me that Chanpion sparks are not good ....

1. What are the best spark plugs for my engine?
2. I have a pair of NGK iridium sparks, what about iridium?

Thanks
Marcel

 

Champion makes the HD plugs

 

Since you don`t mention any problems why not just ride it....

 

You are right, no problems so far, I anyway ride it of course, but I try also to prevent any problems...
that's why I ask about the best plugs, whether thay exists or not..

 

Plugs, tires, oil, there is no "best"
Plenty of personal preferences however

 

I like Autolite. I like them because I’m convinced they yield the best performance, you can still get them in metal grey, they are a great value, they offer several heat ranges, they are readily available.

I don’t like Champion because I have not had good luck with them. As you gap the electro wider and wider to create a fatter spark their point of not being able to go as wide is evident, especially with high compression motors. They also seem to foul out sooner.

I don’t like NGK because they don’t perform any better than the Autolite, cost twice as much, are harder to find, don’t offer as many heat ranges.

If you run NOS or other additives I do like Accel plugs (yellow center) They don’t gap as wide as Autolite, but the base melts faster than a piston when you experience detonation on big high compression motors.. sorta like cheap insurance to protect your motor.

If some poor gullible naïve guy goes dual plug, Bosch is useful for the second plug. They are a little shorter and I ran high compression and liked to create as much squish as possible and due to the shorter plug size they fit better and ran ok. Don’t dual plug your heads unless your in the dessert and can only get 83 octane gas or your running such a high dome (over 12.5:1) that you need the dual plug to ignite the mixture.

 

I have owned my 1989 Softail since new, never had an issue with a Champion RN12YC plug, or the OEM plug, 5R6A.

In fact, in over 50 years working on aircraft, cars, motorcycles, lawnmowers etc., I have never once had a problem with a Champ plug.

 

you have an 87 year old evo… much more to worry about than the brand of plugs.

 

Thank you

 

you my friend mr. dan is an rare exception
i will not buy them. they used to be good when owned here in the states and only had issues when they had labor issues. jump ahead, tired of the usa labor force and sell out the head ache, they are china shinola.
toooooo many bad experiences to relate, but:
7042 waukesha miss firing badly, went over to the platform and the plugs were wore out, figure since it is 24/7 runtime and 80>100% loading. pulled out a BRAND new set of champions, installed and the engine would not even start, just fart.
spent time troubleshooting everything else, nada!!! i cleaned and gapped the old plugs, whall-la, fired right up, hummmmmmm, went to stitts. i could go on but tooooo tiring!!!!