I went in Saturday morning, and haggled myself into an 06 S40 with a little over 12K miles. The bike has a dent and scratch on the side of tank, and missing the left triangle cover, so the price was down from some others I was looking at. I made it about half way home on the bike before it started coughing and sputtering and I limped back to the dealer and they reluctantly had the mechanic take a look, and then he rode it around a bit. They said the detail guy had mistakenly overfilled the fuel tank, and a hose from the tank vent to the carb was sucking fuel as a result. They drained some fuel, and sent me on my way. I made it most of the way home before it started acting up again, but opted to just get home and figure it out as the dealers mechanic didn't impress me at all. I located this forum and began reading for common issues and discovered the petcock test, which i promptly did and found the vacuum side had fuel in it. I plugged the carb port, and the vac line, switched to prime and rode around the yard, and it quickly cleaned up and stayed running then. I went down this morning and took my written test for my motorcycle endoresement, and took out a insurance policy on the bike and came home staring at it thinking, I just have to know how far that famed tensioner is extended. Got my drain pan and tools and proceded to drain some of the blackest oil I've seen in awhile. (Dealership services all bikes before sale). Pulled the clutch cover and I knew before measuring. It was right at 22mm, and starting to elongate the tensioner bore. I dont like leaving things in pieces, so I buttoned it back up, poured fresh rotella through till I got clean oil out the plug. Refilled & started and rechecked and topped off. I'm thinking the filter probably isn't new either. The bike looks great other than the tank scrape, runs quiet and rides excellent with more torque than anything I've ever ridden. At this point I'm planning on a new tensioner with a mod from machine shop for extra hole, clutch cover gasket, filter & oil,  and a 660 petcock, and check valve lash. I really like the way the bike handles, and the power is more than adequate for my needs. For now it will hang out in the garage while I save up for parts.

They said the detail guy had mistakenly overfilled the fuel tank, and a hose from the tank vent to the carb was sucking fuel as a result.



Horse CRAP

Ditto on all the above...and welcome to the group. Thankfully it seems you have some mechanical background,or at least some natural talent. Just think if someone totallly new to bikes and with no mechanical skills had ended up with with your scoot. Sounds like they would have been SOL with that Stealership!

JOG2 is right. I have crammed the tank to virtually overflowing on several occasions. No issues with the stock petcock yet.

gone fishing

I'm impressed. You realized that the dealer prolly knows less than you and promptly came home, figured out the problem(s) through research, logic and some common sense, and then fixed them.

Don't know what else to say other than nice work dude. I wouldn't say this is a rocky start though, you definitely got a handle on things. Sounds like you're gonna do just fine around here.

*edit* Wait, I gotta find fault in something though. I'm gonna say it was kinda hard to read your post without any paragraphs.

Welcome to our new member.....To get rid of the backfiring when you roll off the throttle and improve throttle response drill out the brass plug covering the idle mixture or pilot jet screw located on the right side of the carb body (see pic). Be careful and don't push too hard on the drill bit or it will drill into the brass screw..(and then you are truly screwed). There is a small gap between the brass plug and the brass screw so let the drill do the work...press gently and you will feel when it penetrates through the plug. I used a SHARP 1/16 drill bit and then put a sheet metal screw into the hole and pulled the plug out with a large pair of pliers. On some carbs it might be stuck good and hard but mine pulled out after I had a friend hold the bike from tipping over on me (I did have to pull quite hard to get it out). Now back the brass pilot jet (I call it idle mixture) screw out until your idle no longer increases then re-adjust your idle speed screw to lower the idle speed back down where it should be. I fine tuned mine after driving a few miles and ended up turning the pilot screw back in about a quarter turn. Here is a pick of the brass plug drilled out on my carb. You can also find this and more carb tuning tips in the tech section from Lancer...also check the marketplace for Lancer's Performance Parts at the top of the section....I bought two of his Big Bore Kits and they are quality stuff at reasonable prices...quick shipping too!

Cap the tap on the carb and leave the vent line open and you're good to go.