Exhaust springs?

[2 Wheels]

What are those for?
And what are reeds?

[Postigo]

To keep the pipe in place and to allow some flexibility in case of an impact. The reeds are little flappers that works as a check valve to allow the flow the air and gas mixture in one direction only and at the same time prevent the back flow of that mixture during the compression cycle of your engine.

[2 Wheels]

Thanks Postigo. Very short and complete replies. So the exhaust isn't connected to the engine with bolts?
Is it just stuck in there with springs holding it on?
Thanks.

[Postigo]

Yep, you are welcome

[diymirage]

well, there are bolts that hold the exhaust to the frame of the bike but the only connection to the engine is indeed those springs
I like to use a small chain (like the one they use on toilet flushers) to get them on or off, you just hook the last link of the chain on the spring and pull :)

[2 Wheels]

well, there are bolts that hold the exhaust to the frame of the bike but the only connection to the engine is indeed those springs
I like to use a small chain (like the one they use on toilet flushers) to get them on or off, you just hook the last link of the chain on the spring and pull :)

Interesting...so is swapping out exhausts an easy job then? Besides the exhaust and the arrestor what other parts would I need?
And what's a good, near stock, simple exhaust to get?

[diymirage]

the only thing you need to remove to get the entire exhaust out is the right hand side number plate
that will reveal 2 bolts that hold the spark arrestor on and 2 or 3 mounting tabs (2 pieces of metal with a rubber bushing cast in between them) that mount the expansion chamber to the frame

depending on the year of the KDX you have several options for exhausts
I have H models so that's the only ones I know about (E model options are different)

you have the FMF woods pipe for low end grunt
FMF rev pipe for high end revs
(I think they were also called gnarly and fatty pipe but im not sure which one is which)
pro circuit makes a good all round pipe (little bit of gain everywhere) as does bills (or did bills, I think they went belly up a while ago, I have a bills pipe on my plated KDX and its a good allrounder aswell and not as loud as the FMF I have on the project bike)

as for spark arrestors, the only gains you will get out of replacing those is weight loss over stock and higher bling value
they haven't shown to make any more power over stock


if you decide to only swap expansion chambers you can do so while leaving the spark arrestor and number plate installed
but even if you decide to swap the entire exhaust it shouldn't take more then 30 minutes, depending on how slow you drink..i mean, work


as for other parts, there is a rubber coupler between the pipe and the spark arrestor which you will reuse and there is a copper washer that sits in the cylinder, in the exhaust port
there are also 2 rubber o rings on the neck of the pipe that seal it into the cylinder
these fail at times and several people have found a bead of high temp RTV sealant to be a good alternative

[2 Wheels]

Great reply DIY. My concern is my exhaust (96) is too old and possibly restricted. Am I just being paranoid?
I drain that spark arrestor once in awhile, and a few teaspoons of black sludge drains out.
Is it possible my exhaust is restricted? It runs fine as far as I know....I have absolutely nothing to compare it with.

[KDXGarage]

Even if you switch to perfect jetting, the old oil and carbon will still be in the pipe and spark arrestor. Drain the stock spark arrestor with the bike running.

It doesn't sound like a problem.

[2 Wheels]

Even if you switch to perfect jetting, the old oil and carbon will still be in the pipe and spark arrestor. Drain the stock spark arrestor with the bike running.

It doesn't sound like a problem.

Ok, I'll just stick with the exhaust I have. Thanks. Yeah, it's not a problem. I just wondered about all those years of carbon and oil in the
pipes. But she runs just fine. Just came back from my first hill climbing. Up and down. I was hesitant at first. Had a buddy to show me the ropes there. About 30-40 ft high. Pretty steep. Real soft loamy dirt.
No problems. KDX just ate that dirt up and dug in pretty good.
My first time...I was in heaven. What a blast!!
I'm learning to stand-up on the pegs for better control and weight dist.
Awesome!

[KDXGarage]

Good job!!

[ICRage42]

Not to highjack your post but has anyone used my exhaust?

http://www.dynoport.com/200-500_Models.php his site is funkin up on him. I checked a month ago and was able to go and order and see the pipe and now for some reason it just shows the code.

its a dynoport from rich daly. I was waiting to catch a ride with tyler and check out what hes got to compare. I do believe we have the same silencer and same bike. Although jetted different only thing would be different would be the expansion chamber. But for my pipe I got some really good throttle response and torque throughout. With stock the bike seemed to have no balls at start and just didnt wake up fast enough for me. So I put the exhaust it came with back on (dynoport). Night and day imo. I was going to get an fmf one however that money thing has derailed me. If I pick up one I can compare. I think tyler has an fmf and was gonna do some comparisons. Ya know swap bikes.

[Postigo]

Hi IC, how much do you pay for the pipe?

[ICRage42]

it came with the bike but last I checked when site was working properly it was the same price as the fmf ones.

[Postigo]

Ok thanks

[fuzzy]

Dynoport makes good stuff.