[S2K_Driver]

Hello all. New to the forum. 08' XX, Lexx MX-E slip-on, all stock otherwise.

Anyway, I have an issue that occurred today that I cannot put my finger on.
I just installed a LEXX MXe slip-on. I ran it all day yesterday with the silencer installed, no issues. It seems to be running rich, not lean, as I get occasional flames out the tip if revving it, letting off, and going WOT with the silencer out. Rode it most of the day today with the open tip, no issues. So I started playing drift king on a circle section of my play track across the yard from my house, and as I was coming out of a high-G slide, it dies. Figured I was low on fuel in the ON position, so I switched it to reserve. Attempted to start it, backfires, blue flames. Crank again, it starts and idles for a sec, then dies again. I repeat this process for about 2 minutes until I decided not to kill the battery. Pulled it with another ATV to my house, put the silencer back in. Starts and idles, has hesitation on initial throttle input, and then revs fine. Reset the ECU, same issue. No CEL, nothing. The only other thing I can think of is putting a new plug in it, which doesn't seem likely. Or a clogged fuel filter. Or the fact that my dumb ass poured a half tank of 87 octane in because I didn't feel like going to the fuel station before going riding (it was half full of 93, so it was more like 89 octane afterward). Does anyone have any idea what will resolve this, other than me buying a power commander or installing the stock pipe?? Thanks a mil if anyone has an answer.

 

[jfdanie2]

Its from that crappy gas you put in it and I think that you are running lean not rich because of the popping and backfiring. If you want to go the programmer route I would suggest the power commander but that's just my opinion. I don't think you really need one with just a slipon.

 

[S2K_Driver]

I'm thinking you're right, I'm gonna drain the gas and refill with 93 and add octane booster to clean things up. The reason I said it was likely rich and not lean is due to the fact that the flames are from unburned fuel, not lack thereof, but its possible I guess. Thanks for the reply, hopefully its just gas... And can anyone else confirm whether or not I need a PC to tune this? I'm not planning on any other engine mods besides this pipe, as this is just my play quad.

 

[Red-N-BlackXX]

You probably just got some bad gas. Put some good gas in it and see how she does. You might be a little lean because of the slip on and a power commander will solve that. You should be ok without it though? If it keeps backfiring and popping after the new gas. Then i would get a power commander and give her some more to drink!

 

[xx700xx]

Agreed on the lean condition. Octane booster isn't necessary. I run 93 pump with no issues on a 11:1 piston. BP has really good gas, give them a try.

 

[S2K_Driver]

Well....Good news! Disconnected the feed line from the pump, drained the gas, poured new in: Runs fine. I'm guessin' it was bad gas. Now, I have a question: Should I get the PC or am I OK to run without the silencer on the Lexx? Anyone with experience with a slip-on open pipe, no PC?
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[Red-N-BlackXX]

I don't think anybody can tell for sure how your air/fuel ratio is? All these bikes will be slightly different. Only way to know for sure is to put it on the dyno. If it's running ok and it's not popping, stalling or backfiring. Then you'll probably be ok. Always good to be on the safe side though and add a little fuel via a programmer.(dobeck or PC) you'll gain a few more hp too. :tup:

 

[S2K_Driver]

Well, here we are again lol. It turned out NOT to be gas at all: I had the same problem starting again today, went through everything and decided to install a new plug after installing the stock exhaust failed to fix it. While I had the tank off, I decided to check for vacuum leaks between the jug and fuel injection assembly. Sure enough, the clamp on the inside of the boot connecting it to the head was loose, finger loose. Tightened up the clamp, reinstalled everything and, so far, the issue is GONE. No off-idle hesitation now at all, as I still had a dead spot off idle with the stock pipe installed. So, the issue ended up being unmetered air entering at the plenum that the ECU couldn't compensate for. Hopefully this is the last time I have to troubleshoot this thing.