This is the spark plug from my front cylinder which I pulled immediately after a ride. How does it look? To my eyes, it looks like the mixture is probably a little rich, but not terribly so. However, I get terrible gas mileage - not a huge concern since the bike overall runs very well - but the catalytic converter in my muffler glows red at temperature, and I'm trying to figure out if this is because of the AFR running too rich or because of the way the muffler is manufactured. I tried contacting the manufacturer (MF) several times, but they never respond to any of my inquiries. I'm probably going to remove the cat, either way, but I wonder if I should adjust the AFR to run a bit leaner. Thoughts?

 

Plug looks good to me. Get rid of the cat to cool the pipe down then re-tune the AFR and I wouldn't go any leaner than you are now.

 

Looks good to me. And I'm just thinking out loud here...... But I think if your pipes are overheating that would be from a lean mixture. Air gets hotter then fuel.

 

Put it back in and ride.

 

Very clean!

 

If your cat is glowing, its because of a rich mixture. And you do not want a cat that is getting red hot!! I would remove the cat in the first place, unless japan has inspections, but if you are going to keep it, you have to do something about the mixture. Its why you are getting bad mileage, and you may also be washing down the walls of the cylinders. Just because the plug looks fairly decent, does not make for a good A/F ratio. you have a problem there. No cat is supposed to glow under any condition, without damaging the cat. You could also have a cat plugged causing excessive backpressure, and it could do the same. Where do you see the red glow at? on the side of the pipe, or inside the end?

 

not a cat, they get hot from a rich mixture. I want to know where it is glowing. the side or from the inside

 

I noticed it when looking into the end of the muffler one day. I have the stock pipes which I put back on at inspection time. Those also have cats in them, which I've never seen glowing red like this. I've actually leaned it up quite a bit since I noticed this. I'm planning to cut the cat out of there, but to go any leaner and maintain good performance while getting better gas mileage, may require the help of someone with better knowledge of T-Max maps. The thing is, whenever I clear the learned offsets, and let it auto-tune from square one, then write the new offsets (which is in effect keeping the learned AFR offsets that the T-Max is telling me that the bike requires for my riding style), gas mileage worsens...

 

looks a tad rich to me, leaning it out may if fact make it run better along with getting better mileage.

 

You can get bad mileage from either too rich, or too lean of a mixture. I'm not familar with the thunder max, why don't you contact Zippers and see what they may recommend. they might be able to send you a file to download to start with all over again. but trust me those cats shouldn't glow, that means they are working so hard to convert the hydrocarbons to CO2. I've seen cars catch fire over this