My son has an XB & I have an MT5 - both have CPI exhausts & High Flow Air Cleaners - we are running NGKR CR7HS Plugs - plugs are burning light brown but motors were stalling at idle last time to pits - both motors are making good power - are these the correct plugs ??
Correct spark plugs
- Thread starter Ronk
- Start date
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Have you adjusted the idle screw at all?
I've been using NGK CMR7H (3066).
Here is a good spark plug chart that gives you the meaning of the numbers (in case you care, I was interested, so I looked it up
)
http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf
Looks like the only differences between what you are using and what I've been using are the M and S. Compact (M) probably doesn't matter. I'm not certain what the differences are in a standard electrode.
C: 10mm thread diameter
R: Resistor Type
7: Heat rating number (2 Hot ---- 11 cold)
H: 12.7mm thread reach
S: Standard 2.5mm center electrode
C: 10mm thread diameter
M: Compact Type
R: Resistor Type
7: Heat rating number (2 Hot ---- 11 cold)
H: 12.7mm thread reach
I've been using NGK CMR7H (3066).
Here is a good spark plug chart that gives you the meaning of the numbers (in case you care, I was interested, so I looked it up
)http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf
Looks like the only differences between what you are using and what I've been using are the M and S. Compact (M) probably doesn't matter. I'm not certain what the differences are in a standard electrode.
C: 10mm thread diameter
R: Resistor Type
7: Heat rating number (2 Hot ---- 11 cold)
H: 12.7mm thread reach
S: Standard 2.5mm center electrode
C: 10mm thread diameter
M: Compact Type
R: Resistor Type
7: Heat rating number (2 Hot ---- 11 cold)
H: 12.7mm thread reach
Deluge1
Senior Member
From NGK:
Q: When should I use a resistor spark plug?
A: NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.
NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.
They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.
In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion.
-----------------------------------------
Anyway, if you need a spark plug and you have a Lowes nearby, stop by and look around their outdoor power equipment section. The last time I was there they had Champion RZ7C's for about 5 bucks.
Q: When should I use a resistor spark plug?
A: NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.
NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance. This is because resistor spark plugs reduce electromagnetic interference with on-board electronics.
They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, depth finders or whenever recommended by the manufacturer.
In fact, using a non-resistor plug in certain applications can actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels and abnormal combustion.
-----------------------------------------
Anyway, if you need a spark plug and you have a Lowes nearby, stop by and look around their outdoor power equipment section. The last time I was there they had Champion RZ7C's for about 5 bucks.
Last edited by a moderator:
foxys
Well-Known Member
