thoughts on spark plug heat range

[dg400sm]

i live in a hot humid climate and most of my riding is done and three quarters to full throttle, is there any improvement or advantage of running a cooler plug in my drz400sm

i used to own a yz426 and most of my riding was very tight and technical trails in a cool environment,i ran a hotter plug and noticed starting became much easier and less fouling of the plug so got me thinking

[Qqqqqqqqqqqq]

Yeah ... Plug fouling should not be an issue on a well jetted bike with a healthy motor , if you are running the motor hard make sure the jetting is right . A colder plug would be OK for wide open use of the throttle .

[Noble]

is there any improvement or advantage of running a cooler plug in my drz400sm------Yes, if the current plug is being overheated.  How can you possibly run a DRZ400 at 3/4 to full throttle most of the time?

[150ron]

What is the stock plug's make and number?  how often should the stock plug be replaced?  at what milage?

[ptgarcia]

I think the stock plug is an NGK CR8E. On a well tuned bike one should last tens of thousands of miles.

[BillDirt1]

CR8E

[dg400sm]

is there any improvement or advantage of running a cooler plug in my drz400sm------Yes, if the current plug is being overheated.  How can you possibly run a DRZ400 at 3/4 to full throttle most of the time?

i road race with my friends on a mountain range here in thailand, the return journey is about 240klms at which 90 percent is done at about 3/4 throttle and above,of course there will be some corners that don't fall into that rev range but most do,there is no police along that mountain range so its just ride as fast as you like. now that you mention it PTGARCIA i pulled the original plug out at 18,000klms and there didn't seem to be much wrong with it so maybe i just answered my own question. lol

[BillDirt1]

What is the stock plug's make and number?  how often should the stock plug be replaced?  at what milage?

Not sure what the manual says Ron, I know it would last a long time.  Even though, I replace mine every time I have the tank off.

[Noble]

DG---- sounds like fun.  I suspect there is enough throttle on and off to cool the plug.  You say the heat range 8 looks OK, I'd just stay with that.

[150ron]

Not sure what the manual says Ron, I know it would last a long time.  Even though, I replace mine every time I have the tank off.

thanks,  mine has never been changed,  next time i have the tank off,  ill change it too.   ?

[Kx250FRiDeR651]

Seriously. Cheap insurance if you can't remember when it was ever changed and the bike is already apart. A standard NGK CR8E plug is like $4, or spend a lil more for the iridium (cr8eix) which will last a lot longer.

Just remember to unscrew and remove the terminal nut befor putting it in the bike if the new plug has one screwed on already.

Spark plug gap .7 - .8 mm (.028 - .031 in)

Edited November 26, 2015 by Kx250FRiDeR651