Two Wheel Forums banner

Spark plug wire resistors.

6334 Views 4 Replies 3 Participants Last post by  No Worries
To get a hotter spark, I use non-resistor plugs in my CBR. I read about how Honda uses a resistor in the spark plug cap, right above the spark plug. I found a site that describes how to take out the resistor

The site describes how to do it to a two cylinder SuperHawk, but my old CBR had the same thing. It is actually easier than it sounds. All you need is a screwdriver having the right size head to fit in the sparkplug cap and still fit into the wide screw slot. The hardest part was finding 5mm screws. I did this modification over a year ago, and it runs great.
1 - 3 of 5 Posts
Good, ShanMan. I just assumed that a resistor in the cap and a resistor in the plug would cut down the spark voltage. And I wanted the hottest spark. I did a search on Yahoo and found this site about ultralights Basically, the resistors cut down the spark, but make it last longer. The problem is if any fuel or moisture gets on the plug. With the large resistance, there is not enough juice to jump the gap and there's no spark.

I've seen bikes that stopped running in heavy rain and thought that the wires or ignition got wet. Maybe it was moisture in the intake charge that got into the combustion chamber and prevented spark. My old Suzuki has high output (Dyna) coils and wires, and non-resistor plugs. It starts easier than my newer Honda.
See less See more
thirdgenlxi said:
So these resistors are in the coil-on-plug setup, right? Kinda hard to tell from the pics
Not sure about the coil-on-plug since I've never seen one. My 1990 CBR uses conventional coils and short spark plug wires. The spark plug wire has a long (about 8 inch) plastic/rubber extension that goes through the valve cover to get to the spark plug. The resistor is behind a screw (actually the metal snap for the spark plug) at the end of the plastic/rubber connection.

Even though yours has coil-on-plug, it has to have a similar plastic/rubber extension to get to the deeply-buried spark plug. If you look inside the p/r extension, at the metal connector that snaps onto the spark plug, and it has a slotted head that a screwdriver can fit into, you may have a resistor behind it.
1 - 3 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.