Okay, so I got a 2009 S40, JUST rolled over 4000 miles. Has a Jardine muffler, Uni foam filter, and the following carb adjustments from Lancer's jet set: 3 washers in place of white spacer, 55 pilot and 155 main. I KNOW I went way too far jetting it that much. I could smell it, and the air mix screw was turned all the way in. Improved but still present backfire on hard decel. Now also some poofing from the exhaust on shut off. Runs great with half choke, but I gotta keep the idle turned (what seems like) way up to keep it from dying on downshifts when I'm not giving a little throttle to even it out. So I know I got that all jacked up, and I'm open to suggestions. Pretty much resigned to swapping things out unitl I find the right mix. Oh, and still trying to plug the leaks from the header/muffler connection. Argh.
   THIS IS THE BIG PROBLEM: Met up with two buddies to go riding in Hill Country today. Looking forward to this ride all week. Get twenty miles in, cruising a steady 70-80, suddenly feel like something "went". I honestly thought a hose had come off the carb or burst or something- very hard to explain. But I'm suddenly out of gear. Engine running, throttle works, but gas no go. Downshifted and upshifted, no joy, eventually coasted to the side. Two buddies with fuel injected bikes stand and stare at it with me for a few minutes (not very helpful). No leaks, no bust hoses, no fuel pouring out. Start it up (did not want to start) get on the road, everything is good then 15 minutes and Bam. All over again. I do this again, then limp home with no issues at under 50mph.
W. T. F?
  I have theorized this has something to do with heat???? Maybe I'm running hot and rich, oil heats up, something in the tranny/clutch screws up. Bike sits for a minute, cools down, works fine until I'm running fast and hot again then repeats? I'm fairly comfortable turning wrenches. This bike is not that complicated, but I don't know too much about the tranny and clutch. Anyone got any great ideas? Just tell me how I jacked this bike up so I can fix it and ride before it gets cold!

Engine kept running, but felt like I had the clutch pulled in. Out of gear. Would not go into gear from 5th all the way down to first.

Yep, checked the clutch cable. All looks good. I just don't know what the hell is going on... I feel like it is realted to my recent rejetting, just because of timing, but I'm stretching for a connection. The bike only has 4000 miles on it, so I've got a short list of things that could have worn out already.... Fluids all done at 2300 by previous owner.

Start by making sure the exhaust is air tight to eliminate that issue.
Replace the pilot and main jets with the 52.5 & 152.5 jets.
Set the pilot air screw @ 2.5 turns out.
Double check the float level to eliminate that as a possible issue.
Install new plug.

Test ride and report results.

versalgen1: I haven't checked it yet, but your theory syncs with my common sense answer- heat is the culprit. If rod is at the margin, do I order just the next size down? Or go all the way to the shortest length? And will there be a corresponding clutch cable adjustment?

Lancer: Thanks much. I know what I'm doing the next couple of days. I guess "If it's worth doing it's worth over doing" may not apply when jetting carbs...

oldNslow: Not my first time running the bike like that, but first time in this location (San Antonio). Previously in Birmingham, Al. Not sure of sea level changes, but hot and humid is hot and humid. Although today was a pretty nice day. Which is why I'm so upset to lose it to mechanical failure!!!

  Thanks all, at least I have a direction to head in. I appreciate the help and will report back when I fix it or break it some more.

versalgen1: I haven't checked it yet, but your theory syncs with my common sense answer- heat is the culprit. If rod is at the margin, do I order just the next size down? Or go all the way to the shortest length? And will there be a corresponding clutch cable adjustment?



Verslagen is leading you in the right direction -- follow his instructions and POST BACK WHEN YOU COMPLETE WHAT HE TELLS YOU TO DO.

Versy, when you get his clutch rod right find out what oil he is using -- he should not have "heat related" anything using the modern synthetic recommended oils.   And yet just this past week we see a guy cooking a piston due to varnished up stuck rings and a clutch rod misbehaving due to "heat" while running at full speed ?????

My opinion, go for the things that are easy and don't open up the engine first.

What JOG said about the cable.  Check it when the engine is hot.

What OldNSlow said about the oil.  Maybe the wrong stuff was put in there, maybe it has broken down from the heat.  Changing it out with the "right stuff"  (Does he need to do anything to clean the clutch plates?  Can he do it chemically without opening up?)

Then call me, and let's go ride them hills!!!  (I ride 'em every weekend, I know all the roads worth riding.  I live north central SA (1604/Buverde Rd))  

Oh, and youzguyz, I'm down in Southtown. This place is hopping on First Fridays if you haven't seen it!