Need to Wake up 125

Now that we have our carb issues resolved, looking to wake this bike up a little bit especially on the bottom end. I know a new pipe is probably a fix as well as a new jetting; however, looking for advice on what pipe (we are a big FMF family) and what jet size. Any and all assistance is welcome. Thanks!

Im running a Pro Circuit pipe and stage 1 hot cam, It REALLY woke the bike up. Do the air box mod and bump your jets up to a 110 and 17, shim you needle a little too.

We've tried the Yosh and the Supertrapp on the DR-Z125 motor.

I think the supertrapp was the best, the Yosh was insanely loud for no good reason - you may as well save the money and just buy a piece of straight pipe. Actually, you may as well just cut it off at the head, I think it would have been quieter.

Supertrapp is nice, tunable, very reasonable volume.

Problem of course is finding a supertrapp, but they come up on eBay now and then. Paid $98 shipped just over a year ago.

What about modifying the stock exhaust? You could remove all the baffles and chambers from inside the can and make it like a straight through exhaust. It's free and I bet you see 90% of the gains you would with any top of the line exhaust for that bike. Just a thought if you want to save some $$$.

The only problem with hacking your stock pipe is your bike will sound like a bumble bee farting in a tin can...

The length,diameter, and shape of your header is tuned for performance. (This takes into account the amount of backpressure the silencer is producing). Does this really matter on a stock, 8 horse power motor? Probably not. But true gains will be seen with an aftermarket pipe. Remember noise does not always equal fast... if you could just remove the guts of a stock muffler and get good gains than everybody would do it. Most aftermarket pipes will be larger in diameter. Big gun makes a good setup. I have ran them on my drz for years. There are lots of aftermarket pipes to choose from. All of them will provide better performance than your stocker....some just do it better. Nasty noisey bikes suck


On my son's KLX125, I put in a Wiseco 61 mm, 11:1 piston and also a Hot Cams stage 1 cam. Jetted with 110 main and 20 pilot jets. I have a "modified" stock exhaust on it and it works well. Of course I haven't tried any other exhaust so have nothing to compare to. He wants to get a good exhaust but I can't see any specs on the sound levels. I don't want it to be too loud. What can he get that isn't too loud and how much performance will it add?

i have a t4 pro circuit slip on and it really turned the bike around,

and it not THAT loud it has a nice deep tone

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