In the interest of providing the group with what I hope to be clear information (AFR meter data) on the most common basic mods (while I wait for my DJ lit from ProCycle:), I put the bike back to pure stock for a baseline. Except for the header weld grind which I can’t reverse. In MX_Rob’s epic needle comparison thread, he at one point did back to back AFR runs with the un-ground pipe and then with the header weld ground down, and saw no impact on the AFR readings so I don’t think this should skew the data. So the baseline I started testing with today is a completely stock air box with the snorkel installed and stock main jet (MK 140), and NO shim. The bike is a 2008 DR650. Geared one tooth down on the CS Sprocket, and I am at 65’ ASL. (East side of Orlando FL). This was a new experience for me because I pulled the snorkel out and started playing with the jets the day I got it. Interesting! The Suzuki engineers knew what they were doing. They just didn’t have the same goals you and I may have. In almost all cruise conditions, the meter is showing at or near 14.7. Sometimes flickering a little higher and sometimes a little lower but averaging right on Stoicimetric. At WOT I was seeing low to mid 13’s. So for from a passing EPA regs and max MPG, they hit it right on the nose. But, if I snap open the throttle; I get the big bog I have heard so much about. The AFR jumps to the red and reads 17-18-19 for just a second or so. Very annoying. The front wheel is hard to lift even in first. If I bounce it and catch it just right it will come up a little but not very impressive. Cruise feels a little rough and “lumpy” but not too bad. If I pull on a little choke, it smooths out. So far this is about what I was expecting. But stand by! The next step was to pull out the snorkel and leave the jet and needle stock. I was expecting to see everything get leaner and the bog to get much worse. WRONG!! It got richer!! Bog all but disappeared!! This can’t be, I MUST have screwed up something, so back in with the snorkel. Same results as before. Back out with the snorkel, just 3 minutes to pull the seat and the snorkel so identical conditions. But again it got richer! *** is going on here?? :confused:I put the snorkel back in and went for a long ride, stopped pulled the snorkel and rode back home. Same results. There must be some vortex, or fluid flow kind of magic at play here with the snorkel that I have no idea about. Time warp, worm hole, alternate universe, I just don’t know. But the plane fact is that the jetting is wonderful, if a little on the rich side with stock jet and needle and no snorkel. WOT drops to the 12.5 – 13.1 range. Cruise at every speed I tried is around 13.5. Front wheel comes right up in first gear with just quick twist of the wrist. A very slight bog sometimes but nowhere near what it was with the snorkel in. Going up in the main or shimming the needle would seem to be the logical thing to do, but from what my meter is telling me it is exactly the wrong thing to do! Interesting that ProCycle said he had to go DOWN on the main when tuning on the dyno with just the snorkel removed to get max power. I didn’t understand that at the time but now it makes more sense. Rchill said he was running with snorkel pulled and stock jets and when he put the snorkel back in, it didn’t seem to run good. Now I think I know why, he was use to the much better running no snorkel and stock jets setup so putting the snorkel back in made it run worse. So if I haven’t missed anything or made any gross errors, the good news is that for stock air box and needle setups, just yank that snorkel out and you have a much a much stronger and better running bike. No need to change the jetting! But don’t throw away the snorkel. Save it for when you want to take a trip and get max mileage. Just snap it back in. No jetting change needed. I did experiment with the needle shimmed at both .030 and .040, and the snorkel out. As expected (for once!) they made the mixture just a little richer. Not much difference between .030 and .040 and both a bit too rich but ran well. They don’t seem to hurt anything but will reduce MPG a little. So I wondered if I could uncover one of my 1” holes to lean it out a little. NOT. It got way too lean. Cruise AFR went to 15-16. I didn’t even get off the block before turning around. I am going to run with the stock jets until I get the DJ kit and then start opening up those air holes again!! I want to see how big I can go on the air box with the DJ needle and jets. Need to get that front wheel up in second gear anytime I want!