Today I took a run out to a place where this a nice long hill I could use to do WOT plug chops and it's steep enough to keep the speed down. It's about a 30mile ride out. It's a beautiful day to ride but wayyyy hot to be sitting on the side of the road in full gear and working on a hot bike.
All the supplies I really needed: 8mm wrench, flat screwdriver, pliers (in case you can't get the bowl clip snapped back on), marker for marking which plug is from what, a little cup to pour the fuel into from the bowls, some rags, and 4 fresh D8EA plugs gapped to .024-.025".
I pulled one of my iridiums when I got there just to see what my cruising mixutre was like (3/4 throttle ish). I run Iridium plugs regularly.
Made a "practice" run on the Iridiums to see where to pull off and what my speeds would be like. With the hill I never got above 80mph or so.
Nice little spot to pull off.
The Iridium after a WOT run up the hill.
Then I rode to the bottom of the hill, switched the fresh D8EA into #1 and made another WOT run back up.
Looks sparkling clean and white.... uh oh!
I thought maybe I just hadn't held WOT long enough to get a reading so I threw the iridium back in and rode to the bottom of the hill to make another run on that same plug.
Didn't really change it at all.
Hmmmm ... so at this point I was a bit confused. I was thinking the bike was, if anything, a touch rich as I could hear it burble and bog near WOT. The engine sound really changes and if I let off and ease back into it, it actually accelerates better. I think that is an indication of rich. BUT I went with what the plugs were telling me. I threw in 108s instead of my 105s and made another pass up the hill. I didn't even do a plug chop, I could tell the bogging was much worse. I could feel it actually decelerating if I held it WOT and start to die off. If I eased off the throttle and slowly turned in it would accelerate better.
Soooo... at this point I kind of abandoned plug chops. Seems like they weren't giving me correct readings... or I was doing something wrong.
I changed back to 102 mains instead as my gut initially told me I should and the bogging is pretty much completely gone. I don't really want to lean it out anymore though without knowing what my mixture actually is. Running lean can be very damaging. However, my chrome pipes don't have any tinge of color change so I think that is a good indicator that the combustion temps aren't too crazy hot yet. I think I may have to book a dyno session later this summer to confirm my mixture but for right now the bike feels like it's pretty happy.
When I got home I cut the threads off the plug to reveal a clean white electrode.
Maybe an ever so slight tinge of coloring that goes about 2/3 of the way up the electrode but that's it. Maybe that faint line is what I'm looking for? I dunno.
The hill is about 1/2 a mile long and I thought that would be long enough to get a good reading. Any thoughts on that?
Ken at Cycle X did mention that he didn't really like using plug chops for tuning. He said you just need to *feel* how the bike is running. It will tell you when it's happiest. I think I have done that pretty well.
Anyway, the bike runs very well now. No fuel leaks if I don't leave the fuel on while its sitting and no oil leaks. The tach is a bit bouncy and the front caliper may have an ever so slight seep to it yet but overall it's great and very rideable. It seems to really love to cruise at about 75mph.
I'm up to 370miles on the rebuild now. Woot! I'll do another oil change at 500 miles total and then I think I might let it rev out! I'm itching to hear it scream!
IW
