Sparkplug Question

[AwfulSmokey]

I bought my bike about 1 1/2 weeks ago and have no idea what the guy before me did to it.

I took it out Saturday for my first all day ride. The bike ran nicely. On the way back i ran it out of gas(yeah i know <sigh> )I put it on reserve and went on my merry way.

The next day i went to go put around and the bike wouldn't open up. If i cracked it past 1/4 throttle it sounded like it was running out of gas. I thought maybe some crap got in the carb. Today i took it apart and cleaned the carb, took off the tank, emptied and cleaned it. I got it back together and would barely start up and then die. I took the plug off and it was oily. So i decided to replace the plug.

I looked up in my manual what plug it needed and went and bought one. I believe it was a NGK B9ES . I looked at the old one and it was a NGK B8ES . I put the new plug in and noticed right from first gear it had more snap. Now my question is.... does the 9 burn hotter than the 8? What would make the guy want an 8 in it? Either way my bike runs alot better now, i just wondered what the reasoning was. Thanks in advance for some info.

 

[Rotorranch]

NGKs 9 is colder than an 8.

A lot of folks will run a little hotter plug for slow, tight riding. It helps, but getting the jetting spot on would be a better choice.

I sure thought the KDX was supposed to use an 8. :whoa:

Rotor

 

[AwfulSmokey]

I forgot to point out that changing the spark plug fixed whatever was happening. I guess i will buy an 8 as well and see what a difference it makes.

 

[Rotorranch]

A new plug often cures the problem, but not the cause.

Jetting and heat range go hand in hand.

The KDX that stays here is on the same plug since this spring. :nod: No fouling. And it's a rookie rider.Lots of plonking around. Not haulin @$$.

We run 8ES here on the KDX. 50:1 Golden Spectro. Amoco 93. Can't recall the jet numbers offhand, but dropped the needle one notch, and one smaller on the pilot from stock.

Rotor

 

[Rotorranch]

A new plug often cures the problem, but not the cause.

Jetting and heat range go hand in hand.

The KDX that stays here is on the same plug since this spring. :nod: No fouling. And it's a rookie rider Lots of plonking around. Not haulin @$$.

We run 8ES here on the KDX. 50:1 Golden Spectro. Amoco 93. Can't recall the jet numbers offhand, but dropped the needle one notch, and one smaller on the pilot from stock.

Rotor

 

[John Harris]

Just what rotorranch said: New plug cured the problem not the cause. Run an 8 plug, set needle clip in second ring from top, and jet for your conditions (usually much leaner than stock) and enjoy the rides and rides. Cheers John

 

[XMotoX]

The manual for my 2000 KDX says that the standard spark plug is an NGK BR8ES. And this is what I run in mine. It also says you can run a BR9ES or a BR7ES, but it never says anything about just a B8ES. I heard my dad say something like the "R" means resistor and it kinda confused him that this was the plug it told me to run in my bike.

What is the difference between the BR8ES and B8ES? Is one better to run that the other?

 

[BSWIFT]

Most CDI units need the "R" plug. It can cause unusual problems that are hard to diagnose. Better to use the "R" plug but the non"R" plug will work in a pinch.

 

[Rotorranch]

Most CDI units need the "R" plug. It can cause unusual problems that are hard to diagnose. Better to use the "R" plug but the non"R" plug will work in a pinch.

:nod:

 

[AwfulSmokey]

I'm looking at the service manual for 89-94. It says to use a NGK B9ES then it has the Canadian and UK symbol and says NGK BR9ES

 

[Rotorranch]

Use the BR8es, just to be safe. I've used non-res plugs alot, with no problems, but I've been told it can cause cdi problems. :whoa:

I just think a 9 is too cold for easy riding. :ride:

Rotor

 

[BSWIFT]

Rotorranch is right. If you do extended WOT use a 9 otherwise use the 8 and get your jetting nice and clean. You will be pleasantly surprised with the results.