spark plug

what spark plug is in the 01 yz 426 my dealer gave me a cr9e and i think thats what i pulled out of bike but i threw it away and cannot check but the manual has it down as a cr8e

CR8E is standard. The CR9E will work but it is one step colder. Depending on your jetting it may be more prone to fouling.

[This message has been edited by enmerdeur (edited 03-10-2001).]

I'm in Houston Texas, sea level 70 degrees. I switch to a CR9E and it lasted about 3 hours, before it fouled.

I went back to the CR8E and its fine now. There is a platinum version of the CR8E. I think CR8EVX. I have not been able to find one though.

------------------

Rick

01 YZ426F #85 Vet C

Does Splitfire make an equivalent plug? Has anyone used it?

I guess one of the nice things about the YZF's is we don't have mess with plugs nearly as much as with the two smokes. You almost forget you even have a plug. My first plug went two years before I changed it and only changed it as a precaution during my winter overhaul.

Originally posted by enmerdeur:

Does Splitfire make an equivalent plug?

I’m sure I’ll be corrected if I’m wrong, but IMO the Splitfire is 90% hype.

As soon as one of the “split” portions has .00001% more resistance than the other (carbon buildup, wear, or mfg. tolerances making it unequal to begin with) the spark will ALL travel to one side, nullifying the whole “Splitfire” advantage. But I’m sure you can get an appropriate Splitfire model for the YZF.

That is how I see it. Can anybody poke some holes in this argument? I’m always willing to learn new things…

BTW I also fouled a BR9E, the only plug I ever fouled.

Good thinking, but that is not the entire story. The air gap makes up the bulk of the resistenace not metal in the plug. The spark is looking for the least amount resistance to ground.

------------------

Rick

01 YZ426F #85 Vet C

I run the CR8E and have had very bad luck with the CR9E (lasted only 1 ride)!

Remember guys, Electricity only takes the least path of resistance, and not 2 paths! The splitfires work great in 2 strokes but horribly in YZF's (im sure someone will disagree but think about it)! Just my $.02!

Garrett

------------------

I get my kicks on a 2001' YZ426!

Friendswood, TX

i might be wrong on this one but i thought that the heat range of a spark plug was referring to the combustion chamber temp meaning you use a colder plug for cooler temps in the combustion chamber such as in using race fuel, and that the colder plug actually runs hotter to compensate for the lower operating temp in the combustion due to race fuel or outher mods to pervent fouling . in outher words the heat range of a plug is not talking about how hot the plug actually runs at but at what combustion temps the plug works best in so a cold plug should actually run hotter so it will not foul in colder combustion temps and a hotter plug actually runs colder to prevent preignition if i am not correct please correct me i am pretty sure this is correct

Originally posted by forloop:

The air gap makes up the bulk of the resistance not metal in the plug. The spark is looking for the least amount resistance to ground.

I didn’t do a very good job there…

Carbon buildup, wear and mfg tolerances (and a buggered gapping job also) will change the distance and thus resistance.

So as soon as one ground becomes .00000001 mm further (or closer) to the electrode than the other all spark will go to one side and it will no longer be a Splitfire.

How’s that?

Originally posted by yzf:

…the heat range of a plug is not talking about how hot the plug actually runs at but at what combustion temps the plug works best in so a cold plug should actually run hotter so it will not foul in colder combustion temps and a hotter plug actually runs colder to prevent preignition…

You are exactly incorrect (you just flip-flopped one thing).

The heat range of a plug refers to how much heat energy it will remove from the combustion chamber. Plugs of all heat ranges have the same optimum operating temperature, but the heat range affects how hot it gets (this part you got exactly right).

So if you melt a plug that means it was absorbing too much heat energy, therefore you need a colder plug (this is where you flip-flopped).

Too cold and the plug absorbs too little, deposits build up (instead of burning off) and voila, you’ve fouled a plug.

As the hotrodders say, “The hotter (more compression) the motor, the colder the plug.” That’s how I remember which is which.

(my usual disclaimer follows)

I think :)

Hick:

You got it that time. :) I agree that a forked plug will not do you much good.

The goal it to get your plug to be self cleaning. Which means your plug must operate at the 500C to 850C range. Any hotter you blister the ceramic any colder and you will not burn off the carbon.

For more info on plugs, try this link in the tech section. http://www.ngksparkplugs.com

Like Hick said, you the plug temperture refers to how much heat it will remove. A colder plug has less surface area exposed to the combustion chamber. So it does not heat up as quick.

------------------

Rick

01 YZ426F #85 Vet C

[This message has been edited by forloop (edited 03-12-2001).]

Back to the original subject...I have used CR8EVX's in both my 400 and my new 426. I have never fouled one of them and they seem to add a (very) slight improvement in throttle response.

They are slightly more expensive than the CR8E but, IMO they are well worth the extra 1-2 dollars. I have never had a hard time finding one of them at my local shop either!!

yzernie

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now