500 Plugs

R

Rob7

Full member
Location
Perth, Oz
The idle problem with my 500S has now been resolved (rotor pick up was miles out and needed a redrill), and now idles around the 1000 mark. I am running D8EA plugs - but after100km from new they came out as per the attached picture. I am no plug expert - but do these look too hot/weak? Jetting is standard (115 main) but with K&N in and a free flow exhaust out.

Rob
 

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Looks like you have a clean burning motor there Rob  ;)

Plug chop done at wot needed !
Listen for pinking under load!
Won?t hurt to richen up on mixture, is good to have a play with settings then ride.

If your worried with your seat of pants tuning..... best to get it on a Dyno  8)
 
I was pretty shocked to see the plugs that came out of my 3C were similar last time. I have been riding more in the upper rev range. They are usually black and sooty in my bike on past experiance. Main thing to look for is tiny shiny speculated deposits, that's small bits of melted piston deposits and that's really bad.
 
Modern fuels can't give a proper reading with a plug chop, it has to be analysed with equipment these days, but as said, seat of the pants can give an idea if you have experience enough for that. If you have modified exhaust etc and are riding the bike really hard then get it on a dyno regardless. Remember that your main jet only affects the top 3/4 of your throttle opening, under that the other fuel holes are smaller, and the main jet could just as well be lying in the bottom of the float bowl (as I have seen numerous times when servicing Dellorto bikes). Otherwise if your bike is running sweet with plugs coming out looking like that, just enjoy it.
 
Absolutely right about modern unleaded fuels. Can't get a reading, which is a shame cos it used to be a breeze. But ... what exactly is the presumed prob with those plugs? Far preferable to pulling them out and they're black and sooty!
 
Stock plugs for the 500 were Champion RA6HC, which equates more to NGK9 than 8, in my experience.

Prolonged high speed running would require Champion RA4HC, somewhere between NGK9 and 10.

piet
 
You check plugs running the engine under load, ie up hill and cut the ignition without cutting the throttle.

Then you learn that reading plugs with unleaded fuel is worthless.

Paul
 
Paul Marx said:
You check plugs running the engine under load, ie up hill and cut the ignition without cutting the throttle.

Then you learn that reading plugs with unleaded fuel is worthless.

Paul
Click to expand...

Not entirely worthless, Paul.  Just nowhere as precise as with leaded fuels.

Staying on stock jetting with free-flowing exhaust and questionable pod filters is courting trouble imho...

piet
 
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