Project bike is a 1990 CBR1000F, Honda manual says it takes a
DPR9EA which is a resistor plug. While checking out the coils and
plug wires found a resistor in each spark plug boot also. Its my
understanding it should have one or the other. Or is there some
reason this model should have both?? Over 10k ohm for each
of the four wires and plugs seems a bit much.

 

It's a DPR9EA9. It has been said that DPR8EA is also OK depending on climatic conditions.
I don't know the reason., but I wouldn't change it.
Yes it seems like overkill dunnit...........
But why mess with what the book says is right ?
Make an error with heat range and you could burn a hole in something.
Or worse........
NOT a good thought...............

 

Hey Shadow: Thanks for the reply, not wanting to change the heat range
just wondering if I can go with a non- resistive plug since it already
has a resistor in the spark plug boot. Any idea if it came from the factory
with resistive plugs and boots. Or if someone took the wires off another
bike with out resistive plugs and incorrectly installed wires with
resistors in spark plug boot on this bike?? Normally it's one or the other
not both.

 

Not sure - maybe on California models they may have both to reduce radio interference - not sure. I have a Cali model - would be a thought to check other models to check.....
Which do you have - a "normal" 1000F or the one with spaghetti piping (mine's all gone) on the cam cover.......
Would the extra (or lack of) resistance make the bike go any better ? I have no idea, but if so it's worth checking. More spark = more go for your Dollar =
Somewhere in the dim and distant past we posted up a comparative spark plug equivalent with heat ranges and alternative makes. May have been before the War of Independance - not sure......... I know it exists. I used to have it but after two/three blown hard drives I've prob lost it. Maybe Idodirt/kilgoretrout/chainstretcher can assist with this.
Hope this helps.

 

I got rid of both resistors. I use DP9EA9 instead of DPR9EA9 spark plugs. And I took out the resistor at the end of the spark plug cap. The inside metal cap that clips onto the spark plug end can be unscrewed from the cap using a large slotted screwdriver. Underneath is a little resistor and spring. The resistor is tiny. I think I used a 6 or 8mm metal screw, cut down to the same length as the resistor, to replace the resistor. Some say that without the resistor the spark is hotter, but shorter lasting. With the resistor, the spark is less hot, but lasts longer.

I also have a 79 Suzuki GS1000. It originally came with points and condenser ignition. In 1980 I installed a Dyna electronic ignition, Dyna coils, and solid-copper ignition wires. The thing starts instantly on the first jab of the button. If the CBR didn't have that long tunnel for the spark plugs, I would have changed the wires and coils years ago.

 

Slowpoke: I've done the same thing to my 76 and 80 goldwing. Plus I also
have a 1982 Suzuki GS1100L. I normally have pre 1990 projects. Wanted
to see if their was a problem with doing the same on this (newer?)
bike.

 

My project is a standard CBR1000F, I have noticed less resistance
hotter looking spark.