Honda Grom banner
1 - 20 of 20 Posts

·
Registered
Joined
·
143 Posts
The standard plug is CPR6EA-9, but if you plan on doing a lot of sustained, high-speed riding, Honda suggests you switch to the CPR7EA-9.
 

·
Registered
Joined
·
256 Posts
Tried the cpr7 ngk today and it ran lean. Put the 6 back in and burn great. I woukdnt reccomend the 7. If u try it make sureyou check it
 

·
Registered
Joined
·
281 Posts
A 7 is a colder plug then the 6. You should've been running richer not leaner. Hence why its recommended for high speed runs,
 

·
Registered
Joined
·
659 Posts
My 7 plug is working fine. I changed from the 6 to the 7 since most of my riding is wot. I try not to let it idle for more than a minute before setting out is all. I haven't checked the plug though. When I took out the 6 plug after a couple hundred miles, it was a little white but was working fine.
 

·
Registered
Joined
·
619 Posts
You can let it idle for hours ....it will not will not foul a plug .. Its fuel injected and idles at stoich...

Braap

Sent from my A100 using HondaGrom.net mobile app
 

·
Registered
Joined
·
456 Posts
BE SURE TO USE ANTI-SEIZE GREASE ON YOUR PLUG!!! If you don't and the plug gets too hot the threads will seize. A very bad thing. The heat range on a plug relates to it's ability to dissipate combustion heat. It has nothing to do with mixture. The reason Honda recommends a 7 range for extended high speeds is it can handle the higher temps better. It has nothing to do with the spark.
Then there is the projected tip vs standard. For extended WOT a colder standard tip might be better, slightly less power maybe, but lower tip temps. I am trying out an NGK-CR7E,
it is the plug used in my Yamaha Vino 125, (a standard tip) 7 heat range. With NGK a higher number is colder. Too hot a plug can cause pre-ignition (bad), too cold can't hurt anything. Bigger bore, more compression, more cam, more combustion heat. So, you go to a colder plug.
If you go to a from 6 to 7, the plug will be darker (lower operating temp), the mixture (AFR) has not changed.
As a rule projected tips are for high performance engines, standard tips for extended loads, like marine engines , scooters (CVT), towing vehicles and hot climates (Texas).
 

·
Registered
Joined
·
683 Posts
Rule of thumb when using anti-seize compound -- always torque to the low end of the torque range to avoid stripping the threads.


Sent from Docking Bay 327
 

·
Registered
Joined
·
456 Posts
I confirmed this today, from a guy that has been building racing engines for more than 35 years. He showed me his last build a 150cc double cam 4v desmo capable of 16000 rpm.
So he says running a NGK CR7E for extended high load (60mph cruising), is not a bad idea. This is a 1 step colder standard tip plug.
 

·
Registered
Joined
·
54 Posts
for sustained High speed riding Honda recommends alternative plug ...

NGK CPR7EA-9 also called NGK 3901 ..

the one that came on my 2014 stock is CPR6EA-9

{weak/puny performance from this stock plug}

I just threaded in the Honda Recommended NGK CPR7EA-9 3901....

Original stock plug with 122 total miles since bike was new 'CPR6EA-9' plug was burnt carbon black

FYI I think Ducati takes same NGK 3901 plug.

Spark plug Auto part Automotive ignition part Automotive engine part
OLD plug NGK CPR6EA-9 with 122 miles since bike was new ....

....next to new plug with Honda Recommended High speed plug empty box.

3901 plug in bike awaiting first start-up .
 

Attachments

·
Registered
Joined
·
332 Posts
for sustained High speed riding Honda recommends alternative plug ...

NGK CPR7EA-9 also called NGK 3901 ..

the one that came on my 2014 stock is CPR6EA-9

{weak/puny performance from this stock plug}

I just threaded in the Honda Recommended NGK CPR7EA-9 3901....

Original stock plug with 122 total miles since bike was new 'CPR6EA-9' plug was burnt carbon black

FYI I think Ducati takes same NGK 3901 plug.

View attachment 18599
OLD plug NGK CPR6EA-9 with 122 miles since bike was new ....

....next to new plug with Honda Recommended High speed plug empty box.

3901 plug in bike awaiting first start-up .

You lost me. From the picture you posted it appears that your stock plug has some "dry fouling". "Dry fouling" can be a condition of a "cold plug". You installed a plug that is even colder than the stock plug. The number on the plug doesn't suggest you will get any additional performance from it. The number only indicates the ability of the plug to resist heat. So I can see running a colder plug if you had burned up your stock plug, but a burnt plug isn't black.
 
1 - 20 of 20 Posts
Top