New Pipe...need advice

Get a 4 stroke...heck, you can even get one with fuel injection!

Tell huck to STFU and go buy some extra shims & valves for his rolling hand grenade.

What jets are in there now?

As for the main jet; how often are you truly going full throttle?

Yes, pilot & needle usually are the only adjustments I make. Woods racing doesnt allow me to be in the main very often.

Is it bogging/fouling with the new pipe on, or have you not installed it yet? If you don't even have it on yet, I would get it running correctly first.

It shouldn't be fouling plugs just from adding a pipe, there is probably something else wrong. Bogging can mean lean condition but if you are wet fouling plugs then you are rich. If everything else is in good condition with the bike (no clogged filter, air leaks, etc), then you can drop the needle one clip position at a time to see if that clears up the fouling situation, it should at least help since the needle affects a wide range of the throttle position. As far as a guide to show you were you "should" start, don't sweat that too much, there are too many factors in jetting that would probably make that pretty much useless, especially since your bike isn't running correctly to begin with.

Good luck!

Oh, it's a new bike? I might be worth locating someone with experience with this yes, it can be a frustrating and elusive problem. You aren't going to be having much fun fouling plugs, especially if you are riding out on trails.

The first bike I got (after a 20-year hiatus from minis) was a 2-stroke 250. It would foul plugs every single ride. Partly it wasn't jetted correctly, but I also wasn't riding it as it was designed, just putting around on the trails. I got it running better just by putting in a hotter range plug and changing the premix ratio.

A brand new bike shouldnt be fouling plugs unless you are just lugging it around with a clogged filter and a cold plug or something. If its only been out for 2 rides, I'd take it to the dealer and see if they can set it up properly for you.

I wouldnt change two variables at the same time.

Change the needle first and see what happens - its free and easy to do. If that doesnt help, go to the slow jet also.

An iKAT www.ikatusa.com works really well on the 2 strokes, helps with jetting issues.

Use FMF's 05 CR Jetting recommendations. Honda hasn't done changed anything on their 2T's since then.

i have seen bikes like yours with keihin carbs apparently these carbs are sold for 200 to 250 usd. its also a pretty popular husqvarna hop up. i think sudco.com was the supplier. i have also seen people try the jdjetting jet kits for the bike. with great results.

my 144 rm uses the same mikuni carb and its a pain in the ass to jet properly. also if you have a rich lowend on your bike check the float bowl leve.l on my bike it was way off. resulting in spooge running out of the silencer.

thats a good start..the plug should look like chocalate..not too dark..making small adjustments is a good way too go..i put a SST pipe on and it ran leaner..that was the best pipe by far..came on the pipe and screamed..you're doing the right thing..