Spark Plugs

[kzmille]

Fouling, really? I've never fouled a plug on any four stroke and not many in my two stroke days. With my relatively stock (no power commander here) 01 mille my original plugs went 17,000 miles.

[Bill in OKC]

My first shot at iridium plugs, I bought a set of 4 for my '00 Mille. So on my next big ride both plugs had fouled in one cylinder before I got to the end of the block and had to abort. Something odd because it never happened again and the only time in a 4 stroke.

[Micah / AF1 Racing]

I see a LOT of black plugs here at work, mainly on higher mileage street ridden bikes with not so aggressive owners. Futuras and Capos are often the models with the most fouling BUT, 9 heat range in a Capo motor wih low comp pistons and small TB'S and a very under stressed motor is asking for fouling issues. Another reason I like the 8 heat range on the street is that the E10 gasahol we get around here does not burn as hot as the "neat" gasoline available in Oklahoma for instance. The plug's insulator needs to run around 900F to "self clean" and you just have to adjust heat range until you clean plugs with a chemically close to correct mixture.

I think motorcycle OEM's are quick to use a colder plug than is really needed just like the WFO fueling on almost all bikes is universally rich stock, they have no intrest in paying extra warranty claim money. OEM's tend to make choices that insure the motor should survive its warranty period for 99% of owners WITH common mods like pipes and filters. The OEM has to do this ridiculous dance around sort of BS emissions targets AND rich enough under load not to heat the motor too much AND the motors still need to make enough power to keep customers happy. Hence shit like air injection that is only solenoid triggered in the emissions testing range of the motor...

[carlgustav]

Have been following this thread with interest. I ride my '02 Mille mostly on the track for the past couple of seasons and I have the DCPR8E plugs installed. I'd like to ask if I should switch to the 9Es for my track use? I get some 'popping' from the motor later in each day of track use, and she feels a little rougher (pysch maybe) ...

Thx,
ACE

[Micah / AF1 Racing]

On track bikes I would use a 9 heat range plug. Your motor generates an order of magnitude more heat on track than even during "fast" street riding if you're doing it right!

[carlgustav]

So would that be doing 'street' riding right, or track riding right :^)?

ACE

[Micah / AF1 Racing]

If the bike is on the track and ridden there frequently I would call it a track or trackday bike.

[planter87]

give it an "italian tune up" once a week and you'll be fine lol

[carlgustav]

Just a quick follow-up. I ran the 9s last weekend at Barber. Air temp. 108 on Sat. and 106ish on Sun. (gnd temps around 138). No popping or back-firing down the front straight, the motor felt 'good' throughout both days in spite of heat ... same could not be said for me :^) ...

ACE