Picked up a KLX300 exhaust system (thanks, Chris). Head pipe had been painted prior to Chris acquiring it. I sanded it down and I'm planning to shoot it with wood stove paint. Looks pretty good how it is now, but I'm sure it would corrode if left untreated. OEM 250 heat shield bolts right up.

 

its not stainless like the 250 header ?

 

Stove paint will most likely end up flaking off. I've had headers ceramic coated before, its really not too expensive and there are usually a few different colors you can do. I was thinking about having the head pipe on mine done.

 

I'm thinking it is stainless. I'm going to try sanding it a little more and putting it on. If it starts to corrode I may look into ceramic coating it or painting it with the high-temp paint. It's really just a cheap intermediate step before I invest in the FMF Q4 and Powerbomb header.

 

Installed the 300 exhaust system, Uni filter, DJ 2152, 128 main jet, A/F mixture screw 2.5 turns out. Removed smog crap. Fired right up and ran really well, but after it warmed up I got some decel popping. Get a big pop and some gurgles if it's a harder decel. Should I move the A/F mixture screw out another .25 to .5 turn to reduce the popping?

 

I have the same set-up - its worked well for me and is easy on the wallet.

I used a wire wheel on a drill motor to clean mine up. Same method for touch-ups will remove heat discoloration and keep it looking like stainless (which the header is not). Painted my muffler black.

That header pipe is not an exact fit. You may want to add some washers as make-shift spacers where the rear of the muffler bolts to the frame. This will relieve any strain where the header pipe attaches to the engine.

Mixture... turn screw in until idle begins to drop then back out 1/4 turn.

 

donaldor, how many turns out from seated is your fuel screw? Are you also running the DJ 128 main jet? I'm thinking that I'm running rich, so I plan to turn fuel screw in .25 turn and cinch the pipe to the head a bit more (thought I had it good and tight, though).

 

Any strain at the header-cylinder point can cause exhaust leaks and/or warping of the cylinder at the exhaust port.

I installed all the pieces but didn't tighten any bolts. Lightly tighten the bolts holding header to cylinder (don;t torque yet). A fresh gasket is a good idea. Position the muffler and snug up the clamp bolt. Check where the muffler bolts to the frame, there will probably be a gap. Use appropriate hardware to fill that gap (I used sst flat washers). Play around until its lined up the way you like making sure there is no strain on the header pipe and torque everything down. Did I mention using new gaskets? Don't forget new exhaust gasket (sleeve) for header-muffler connection.

If you really have a hard=on about this stuff like I do: that header pipe entrance can be cleaned up and polished quite nicely with a Dremel tool. I ground down the weld, etc. at the pipe-flange connection and created a nice smooth exit for the exhaust.

Not sure about the DJ settings as I had the shop do it. I do know it was setup for use with an aftermarket exhaust system and an 'open' intake (airbox cover removed)