So, now that i've owned the bike for a good bit of time, i've gotten REALLY comfortable, and a little fed up, with the stock power gains, and since I don't really have the money for an entire exhaust kit atm, i'm thinking of just derestricting the crank case vent line, boring out the exhaust can, tossing all the extraneous airbox crap (+ an aftermarket filter), and then rejetting.

Can anybody who's done this comment on the power gains? I'm just looking for a few more horsies. Don't need much power around these parts, but I definetly would like more.

 

I started out the same way, took a 12"long 1/2" bit and frilled through both baffles on the stocker. From the set-of-my pants I would say it was maybe a gain of 1hp. Moved up to a HMF slip-on and noticed a huge gain (and accorind to their dyno about 3-4 more ponies). The HMF are reasonably priced at $220. If you want to go cheaper, the stock klx300 muffler and silencer can be had on fleabay for about $50 total. If you ask theklx300 guys they say the stock muffler is fine as the restrictor plate is removable, but the stock header really plugs things up. A number of folks on this forum opted for the 300 muffler and a header from fourstoke works for $154. That sound like the best may to go on a budget, and would really open the bike up.

http://cgi.ebay.com/ebaymotors/KAWAS...spagenameZWDVW

http://cgi.ebay.com/ebaymotors/KAWAS...spagenameZWDVW

http://fourstrokeworks.biz/

 

Id say your best bet is the KLX 300 system. Do jetting & open air box also or dont bother.

 

My mods are in my signature and I'm pretty happy with how the bike runs. I will eventually go to 331 as I have the 300 jugg sitting on the shelf already but I'm thinking I'll put the money into making it more versatile before more power gains. Thinks like a better seat, spare rims/tires (street tread), some luggage of some type like a top box or dirtbags panniers.

From personal experience I'd leave the airbox lid on, remove the snorkel and go up several jet sizes on the main jet. A 125 main is pretty common, I have a 130 installed now and even so my mileage is still averaging 60-65mpg on longer pavement runs, low 50's in the dirt.

 

I've drilled out the exhaust to 1 3/8-inches and then welded a new end piece (same size)..I installed uni-filter, cut out air box lid and installed 132 main jet, FS 2.5 turns out, drilledslide 7/64 and the bike really woke up (compared to stock), I am also running 13/42 gearing (if you haven't dropped a tooth on the front sprocket..I highly recommend it) NOTE: I am at sea level.

My only concern is that the muffler gets pretty damn hot...i don't know if this is norm? perhaps someone can confirm this. Also, I have not done the crankcase mod or removed the smog stuff...would this help cool the bike down?

 

I didn't notice anything from drilling out the baffles with a 1/2" drill. However, last night I ground down the sloppy welds thatconnectthe header pipe to the end flange. That actually did something good.I'm not sure I gained appreciablly more power, but theengine definately runssmoother at all RMP's. I'm amazed. The difference was dicernable the moment I started it up. I can't believehow sloppy the weldswere in my pipe. Thanks to whoever it was whorecommended thisfree mod. Itmade my motor happy. Who would have thought?

 

Ive done that as well.

 

at which end are these sloppy welds? I may consider doing that as well.

 

Mudjunkie, the smog equipment will make your exhaust hotter because its directing fresh air into the exhaust pipe to continue burning the exhaust so it will meet emission specs. Before removing mine my headpipe would glow orange.

The sloppy welds are at the engine side of the headpipe. Remove the 2 nuts on the flange and pull off the headpipe and either file or grind them down ALMOST flush to the pipe diameter. As sloppy as they were I didn't trust that they had good penetration so I left maybe 1/16" of weld bead sticking up.

 

Thanks..I will check that out..it's getting cold here and not too many nice riding days.