Took the KLX250D (also the exhaust used on the 300) exhaust for a spin today. Its the same as in my pics and videos on page two. Anyway with the removeable baffle removed (didn't get it with it) it sounds great messing around the yard, however at 60 on the road my ears started ringing so I decided that it was a bit too open. Dazjr is running the same exhaust and made up a backplate with a 3/4 ID tube in it to knock the sound level down on his so I figured I'd try something similar minus the tube. Cut out some 3/16" aluminum and went to drill the holes and it dawned on me I don't have a 3/4" drill bit, only up to a 1/2". Tried the half and it was definitely quieter, almost stock like just deeper but all the low end snap disappeared. So I added 2 1/4" holes and tried again, sound was marginally better, not much more performance. Went with 2 more 1/4" holes and its got nearly the same sound as being totally open but at a much lower db level. Mind you I haven't rejetted yet, should be in by next Wed, if the parts are on time. If I sit back on the seat and give the bars a jerk just off idle it will loft the front tire with a crack of the throttle. Around 4-4500 rpm same procedure it will lift the tire with relative authority and carry it quite well, something I couldn't do before. There is no clutch involved when doing the above as I've got a pretty good grip on the bars and haven't mastered the two finger clutch action without smashing my other two fingers.

Doing some math on the outlet area:
The opening on the exhaust with nothing there is 1.3" in diameter giving a flow area of 1.327" squared
With the 1: 1/2" and 4: 1/4" we get a flow area of .393" squared
If I go to 1: 1/2" and 8: 1/4" I'd have a flow area of .589" squared

Where Dazjr's exhaust is 3/4" which gives .442" squared.

Also I noticed that with the stock jetting above 60 with the open exhaust it just runs out of steam, no popping, no cutting out, just doesn't want to go any faster which I believe is due to the exhaust being so open. My '87 350 Yamaha Warrior ATV was the same way when I had a DG Chrome Power pipe on it, bought the bike used and it had the pipe on it and the owner didn't know if it had been jetted or not. It had unbelievable low end but just the same didn't have much on top. With the stock exhuast it didn't pull as hard but would rev higher and would run up to a considerably higher speed.


Also here's what I have on order:
16009-1912--------Needle-Jet,N1TC
92143-1667--------Needle Collar (required for N1TC needle)
92037-1401--------Clamp, Needle Jet (Clip, required for N1TC needle)
92063-1069--------#125 Main Jet
14073-1577--------Duct, Inlet (KDX200 Snorkel)
99924-1240-55-----S/M Supplement KLX250H
92064-1108---------- pilot jet #40


*Update*

Sound is great, running 8 quarter inch holes and 1 half inch. Here are a few pics.





And a full shot:

 

So..........whatcha think?

 

Looks great! Good job!

 

Took it for a ride tonight, went with my parents on our Sporstman 500 HO. Still stock jetting so I didn't wring it out too much on the trails but the low end is a night and day difference, not to mention the sound. Nice and throaty and doesn't get raspy the way it did with the can completely open. It actually feels like a nice sporty bike now, I can only imagine how much more pleased I'll be after Wed. and the rejet. Today was my personal best on the trail as well, made it through several rocky sections without stopping or even dabbing a toe. I usually point shoot, stop, shoot, stop, go some more, wobble a bit etc etc. I just picked my line from the bottom of the hill and went for it in 1st and clutched my way around. Second part was even better super dry sandy section, one very steep hill with a water rut down the center with accumulated debris (dry now but washed out from the rains last week) with a sandy run up to it I generally dread this section and the following few hundred yards as its all sand and varying camber and it generally throws me around quite badly and I've washed out a bunch but never dropped it there. Anyway I found that I can ride the sand better seated than standing up as with the bar position I'm over the front tire too much and I just powered my way through and essentially idled through the flatter parts. Boring story to some but it was actually very exciting for me!.

 

yeah that looks pretty cool [sm=bling.gif] i might have to do that to mine real good job do you like it. try and get a sound level i would like to know thnx

 

I have no real way to get an actual db rating but can post another video if you want. On page 2 or 3 I have a video with it completely open. Titled 300 exhaust pics and video.

 

Hey Bryantjt that looks good are those part numbers from Kal or another co.
Thanks

 

Those are all genuine Kawi part numbers. Can be used with the www.ronayers.com www.bikebandit.com or your dealer.