So I just replaced my Supertrapp Ids2 slip-on muffler with a 2011 stock muffler. My KLR is a 2006. The bike was running fine with the Supertrapp but I didn't want to deal with the re-packing.

Anyways, I put the stock muffler on. It was running fine. I took it to my mom's house (15 mins away) visited for a bit then on my way back the bike lost power then died. Won't hold an idle for long. I had to keep it at high rpms to get it back to the house.

Gas was coming out of the carb overflow hose.

Spark plug - Oil Fouled

Main Jet - 140
So I replaced it with a 148, doesn't say "Kehin" but it fit.

I also discovered 5 holes in the top of the airbox.

The idle mixture screw plug hadn't been removed so I assume they hadn't touched it.

With this information, I'm wondering how I might be able to get my bike back running great with the Stock back on?? Do I use Gorilla Tape on the airbox holes, replace the spark plug and call it good? I'm also going to to check the float height tonight.

Thank you in advance. Please help.

Looks like you have a couple of threads going on the same problem. With the mods you are describing it looks like the Prev Owner knew what he was doing . The 140 jet goes along with the tapered KLX needle I suspect is there. Put it back in. The 148 will be too rich with the tapered KLX needle. The KLX needle has 5 grooves in the top end. The C clip should be in the second from the top groove.
The holes in the airbox are for more airflow and are commonly referred to as the "L mod" they are fine as is.
Regards.... justjeff

not a KLR expert and hopefully one will chime in but......

have you checked for gas in your airbox?
did you replace the jet just prior to this problem??
have you cleaned your carb?

sounds to me like you need to get back inside the carb and double check that your float and / or float valve isn't hung up. i would also confirm exactly what jet you have installed, different brands use different numbering systems.

HTH

Search out cleaning carb with pinesol threads there are many and it will explain how to and I'm sure what settings to use. It also depends where you live to what settings and jets you need.

Now wait for the pinesol jokes and abuse....doh!

I'm starting to think that the PO did know what he was doing. I want the stock muffler to be efficient as possible. If I put back the 140 jet, confirm the tapered needle and leave the "L Mod" should the bike run well with these mods and stock muffler? Because I've want to get the best mpgs possible.

Good advice, the air filter was clogged, cleaned it. The carb was clean as far as I could tell and checked the float height. I replaced the jet after the issue. The bike is running now but will only start with the choke closed and throttle open... Any ideas on that? Did I perhaps break the choke plunger thing?

Hi DV!
What main jet did you end up putting in? Did you put the 140 back in? Did the carb have the KLX needle in? Did You get the float needle to close?
Regards....justjeff

Pinesol is no joke Willys. It is a serious cleaning product and as such, demands your utmost respect.
jj

Haven't got back in there yet to put the jet back and check for the needle but I'll let you know. Should I just leave it as it was with the 140 main jet, holes, adjust the clip on the needle and call it good? If so, that'd be a relief. I wouldn't have to order anything that way...

That is how I would try it. The 140 was in when the aftermarket exhaust was on and it ran fine. You put the 148 in after taking off the exhaust. The 148 is much richer than the 140 if they are the same brand. Where did the 148 come from?

On my '11 I am running a 140 with my needle set to the second groove from the top, Uni filter stock exhaust at around 2000ft elevation. If the 140 was working good with the aftermarket exhaust it will be a little richer with the stock exhaust.
My '03 had a 148 from factory. When I put in the KLX kit and installed the Lexx exhaust ect. I put in a 145. It was too rich. I now have a 142 in.

The KLX needle has 5 grooves and a long taper. I understand the JD needle has 3 grooves. The stock needle is not adjustable and is stepped on the lower end, not tapered gradually like the KLX needle. The long tapered KLX needle allows more fuel to flow through the same size jet than the factory KLR needle does. That is why you need a smaller main jet with a KLX needle rather than a KLR needle.
Hope this doesn't confuse you too much! Long story short ...put the 140 back in and see how it runs. I believe the 148 is way rich.
Regards....justjeff