hot or cold you tell me

[4real450r]

i am running the stock spark plug in my trx 450r . what im asking is every body running this plug or has everybody went to the hotter plug. i guss 8 being the stock and 7 being hotter and with the mods shoudent the hotter plug help. iam running a lot of fuel 192 main but i have to.

[400exrider707]

Why do you HAVE to run the 192? I dont ever see anyone running a main that big even with similar or MORE mods than you. Are you sure your jetting is on?

[440_Turtle]

agreed, thats a mighty big jet. who rejetted your bike? Have you checked the plug color?

[4real450r]

agreed, thats a mighty big jet. who rejetted your bike? Have you checked the plug color?


400exrider707 Why do you HAVE to run the 192? I dont ever see anyone running a main that big even with similar or MORE mods than you. Are you sure your jetting is on?

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withe air box on i was running a 185 main the plug looked perfect i like to drag race. well took the box off put a elimnator kit on (velocity intake). and got lean. keep messing around ended up at 192 plug looks cardboard color. dont know any help would be nice. just bought an elderbrock carb and waiting on it to come in and try it. if it helps i am running the air screw 2 1/4 turns out from bottom. will the hotter plug help .

[GPracer2500]

I think you've got it backwards. Pretty shure the standard 450R plug has a heat range rating of 8 while the optional plug is a 9. The optional plug is colder not hotter. AFAIK, optional plugs are always a colder heat range.

A colder plug operates at a lower temperature. It does this by transfering more of it's heat into the head/cooling system because of a shorter insulater (the ceramic part that extends up into the plug). Colder plugs are less prone to be a source of detonation (because of their cooler operating temperature) but they are more prone to building up carbon (especially if your running on the rich side).

Hot vs. cold plugs does not change your engine's overall running tempurature (unless the change elimintates a detontation problem). They only change the operating temperature of the plug itself.

[bwamos]

Domestic plugs (split fire, etc..) +hot / - cold
Japanese plugs (nkg, etc..) -hot / +cold

Generally if your running a modified engine, getting detonation, and you're jetted properly, you will want a cooler plug that transfers more heat to the head of the engine.

If you are jetted properly and are still getting too many carbon deposits, and fouling the plug, you will run a hotter plug to help burn off the deposits.

Generaly you will never need to go hotter than OEM spec unless you detune your engine or retard the timing for some reason.

If you run a highly modded engine with advanced timing and/or high compression you may need to run a cooler plug. A one size cooler plug will generaly drop your plug tip tempurature by 70-100deg.

In short, OEM spec is fine unless you are getting detonation with proper jetting, then you may look at a cooler plug, but a cooler plug will be more prone to fouling due to build-up if it's too cool.