Runs rough

[Medicoutdoor]

Hey all,
So I’m going to preface this with ‘I’m not very handy.’ I bought an 08 rs sm5 and it came with a two brothers exhaust, and a juice box already installed. I took it out yesterday and it was about 85 degrees. I had about 6 bars on the thermostat and I was in stop and go traffic, not going more than 35 mph. I was constantly switching gears. The bike seemed to hate 1, 2, and the low end of 3. It was backfiring and just didn’t sound right. Once i got up on the highway and let her rip it sounded totally fine. This is the first time I’ve experienced it backfiring and just generally sounding like crap. In my google searching the tuning of the juice box came up, and maybe the mixture is off. Am I on the right track? Is this something the dealer can adjust or can I do it myself? If anyone has any other basic suggestions I’m all for trying things myself first. Or if you think the juice box isn’t the issue I’m open to anything.

Thanks for the advice!
Alyss

 

[Bfromla]

Act as if it didn’t have the juicebox carefully checklugs, wires, & filters:dontknow: opcorn: Never got the hang of fine tuning needle valves to even attempt programming. :gaah:

 

[Peter Aawen]

Yeah, I'd leave the juice box alone, at least for now - there's lotsa other things it might be before you buy into that!! Check the vacuum hoses, they can look alright but if they are anything over a couple of years & not silicone, then when you bend them back on themselves you'll often find they have micro fractures that let air in.... and that (along with old plugs & leads, or partially blocked filters) can make them run rough & backfire a lot in the lower rev range & thru the lower gears, generally smoothing out once you get motoring along. :dontknow: But that'd probably be a good place to start! :thumbup:

 

[johnv50]

Your bike has a 998 engine, are you sure you are revving it high enough before shifting in the lower gears ?? could be an issue with shift points.

johnv

 

[ARtraveler]

5500 rpms is the "happy" spot for the 990 twin engine.

 

[Medicoutdoor]

Thanks for the tips so far! I did know the 998 engine had a sweet spot around 5500 rpms, so I won’t shift until I’m between 5-6. That was particularly problematic on the stretch of road I was on because I was right between gears, it was hot AF, and my bike has never really liked second gear. It tolerates it but it does much better in 3 or above.

I’ll start checking hoses!!