So I've posted before, when I got my 600 last July it came with about 14,000 miles on it and a Jardine GP1 slip-on. CAT is present. When I revved the bike up at that time, even cold, the rpms went up quick and the exhaust had a nice crisp race exhaust sound. At the end of the summer I complained about a muffled sound, and lest pick-up off the line. Over the winter I replaced the plugs, and found that two were barely screwed in all the way and took no effort to unscrew by hand. (I checked the Gap and properly torqued the new plugs). Air filter was dirty and has been replaced with the stock Suzuki filter.
I have already determined that the bike gets better mileage on the highway than in town. I run mostly 93 octane gas. When I rev the bike up, the exhaust sounds muffled or restricted to me, and is not as crisp or higher pitched like it was in the beginning. I checked the rear screen of the CAT, and that still looks the same and not clogged. Today when I started the bike I waited a minute and sprayed water on the exhaust pipes. The two middle pipes evaporated the water a few seconds sooner than the outside, but the middle pipes also have that tuning? Bar running between them. After several more seconds all pipes seemed the same.
The other thing I can offer is that the power doesn't noticably kick in until 5-6,000 rpms, and if I'm in town in 3rd or fourth gear at 5,000 rpms the bike is a dog. I'm not sure what to check next. There is no stuttering, I can't say valves are tapping, but I'm not an expert in the I4 engines. no weird smell from exhaust, and no FI lights. (I have a switch hooked up to the dealer plug in case I get one, I can flip the switch to see the code) RV6John has helped with checking the exca or set valve, and that seems to go through it's rotation properly, (checked by turning on ignition, not starting the bike) I just don't know if it sits in the proper position when the bike is at idle. If it's wide open at idle I've read that can cause a loss of low rpm power, (it's partially designed to create back pressure at lower rpm's?) but should also throw a code?
Last edited by New2Street; 07-14-2019 at 02:15 PM.