Spark plug caps

[yambutt]

Not sure if this has been mentioned but i was installing my factory coils and noticed 1of my caps was reading over 12k and the other one was 1.1 meg so i figured id unscrew the internals and found the spring, flat washer and the back of the screw terminal corroded so i cleaned them off real good and got both to read right at 10k....very simple to do and i think it should be done everytime we change plugs or take the tank off

[yambutt]

I also cleaned the ends of the resistor and metered that to see what i had.....you want to get the final result very close to what the bare resistor reads

[Sparky84]

Yambutt Are you running resistor plugs also?

Do we need resistor plugs if we have resistor caps?

[yambutt]

Its the original caps so they have a 10k resistor in them so you don't need resistor plugs if your running with that,

[yambutt]

The resistor is there to prevent electromagnetic interference from other eletrical devices on the bike so i would say 10k is more than enough and i do believe the originak ngk plug didnt have a ceramic resistor built into it

[balky1]

The resistor is there to prevent electromagnetic interference from other eletrical devices on the bike so i would say 10k is more than enough and i do believe the originak ngk plug didnt have a ceramic resistor built into it

NGK still lists DP8EA-9 on their site, non-resistor type (for 1100 at least).

[Schurkey]

What is the NGK spark-plug cap replacement number?  (1986 FJ1200)

I've been all over the Internet, and it seems that most suppliers are suggesting the XD05F, but some are listing other numbers.

The caps on my bike may have been replaced.  They're Tokai Denso, marked TD T-131.  I see nothing comparable to them in the NGK catalog. These guys are more compact/smaller, and they seem closer to 120 degrees than 102 degrees.  They've apparently got 10K resistors in them, but they vary from 8.5K to 12.5K, with one at 70K.  No amount of cleaning the ends of the resistor will bring the 70K back to reality.

Thanks

[big r]

Check out RPM,s website they have oem. plug caps there

[balky1]

Is it needed to use resistor caps when nowadays NGK spark plugs have a resistor built in them?

[RPM - Robert]

Balky, the proper NGK plugs do not have resistors built into them, DP8EA-9. You need to use resistor caps with OEM ignition setup.

We only use the Yamaha boots now as we had used several sets of NGK boots that wore out very quickly at the internal brass connector to the spark plug top; causing the wire to fall off. We have yet to have a problem like this with the genuine Yamaha ends.

Here are both ends.

Yamaha Spark Plug Boot
NGK Spark Plug Boot

[balky1]

Balky, the proper NGK plugs do not have resistors built into them, DP8EA-9. You need to use resistor caps with OEM ignition setup.

We only use the Yamaha boots now as we had used several sets of NGK boots that wore out very quickly at the internal brass connector to the spark plug top; causing the wire to fall off. We have yet to have a problem like this with the genuine Yamaha ends.

Here are both ends.

Yamaha Spark Plug Boot
NGK Spark Plug Boot

I understand that for DP8, but almost everyone offers DPR8 nowadays.

[RPM - Robert]

Spark plug cap resistance is supposed to measure between 7.5-12 k ohms at 68* F. The DPR8 has only 5k resistance. I would still say the DPR8 is not the correct plug; regardless of who is offering it.

[balky1]

OK, great explanation with graphics for dummies also.