A good friend of mine is currently building a 2010 Kawasaki KLX250S and I thought I’d write up my build for my old KLX. There’s a lot of reviews of these little bikes. I owned a 2006 KLX and built it to be a competent little adventure bike. This blog post is pretty much a copy of the email I sent him as a reference for what I added and changed on my KLX205s.

Safety and Guards

The stock handlebars are fit to be a boat anchor. I like the Renthal CR High. They have a nice sweep and are comfortable while standing without a riser for me.

I upgraded the headlight to a brighter Hella H4 bulb with 80/100 watts. It’s much brighter than stock and runs a fair bit hotter. I never had any trouble with the heat and the higher current draw.

The bike needs a real skid plate, and I liked the one from Ricochet Offroad . It took some serious hits and scrapes over things and never had any problems with bending or causing problems. You can change the oil without removing it and it’s got really nice mounting hardware.

If you’re going to do some technical riding, it’d be good to install some radiator guards. I like the Unabiker guards. They install without changing the stock fan and can take a hit.

I got the kickstand switch wet once and it caused a problem. I removed it - I can’t remember if it defaults open or closed, so check it with a multimeter to see if you can just remove the whole wire or if you need to jump it. This switch is for your own safety, and occasionally some Harley rider dies because they crash with their kickstand down. If you remove it, you need to have good habits about raising the kickstand up.

My 2006 had a HUGE front fender that was great for blocking mud, but was a handful in a crosswind at higher speeds. I replaced it with a Kawasaki Green Fender from Acerbis. It looks like they only sell a solid color version of it now, bummer.

Adventure Gear

I added a Battery Tender and if you don’t have one already, get the USB adapter for it so that you can charge you phone if you haven’t added an accessory port to the bike.

I added a small Pelican case to the tail of mine by drilling some small holes and using hose clamps to the tail luggage rack. It was great to be able to lock it with a small padlock. For saddle bags for longer rides I used a set of Ranger Bags from Dirtbagz. They hold a fair bit of gear and held up well. The never had any problems when I dropped the bike and never tore or had any issues. I kept some small dry bags in them for rainy days.

Engine Mods

KLX Carb Upgrade
KLX 250s carb upgrade

The bike comes from the factory running really lean. With some carb mods to run a little richer and some improvements to make it breathe a little better you can really wake up these little bikes.

Install a KDX airbox inlet to increase the size of the opening in the airbox. It’s a direct fit and installs without any modifications. I don’t like how loud most aftermarket exhaust systems are, and you can keep the stock exhaust if you just drill out the last baffle. Just take a drill bit the size of the exhaust opening and drill out the last baffle.

The bike will probably be 50 state legal, and to really wake it up you’ll need to remove some of the smog controls. Do a forum search for the other smog delete options and include the AIS. I made a small aluminum plate to use as a block off plate.

The carb needs to be re-jetted. You can upgrade to a Mikuni TM36 pumper carb to increase throttle response, but I never felt the need. Instead I upgraded with the following:

16009-1912 Kawasaki Needle-Jet, N1TC 
92037-1401 Kawasaki Clamp, Jet Needle 
92143-1667 Kawasaki Collar with the needle clip installed in slot 2 down from the top
92063-1069 Kawasaki Main Jet #125
92064-1108 Pilot jet #40 Air screw at 2.5 turns out
I drilled the slide vent to 7/64ths


The brakes on my 2006 were great, but for some reason the front brake hard line was routed under the front axle and seemed vulnerable to a rock strike or crush. I re-routed it with a stainless brake line from Bill Blue. It looks like there is a new brake line upgrade available from Galfer for newer KLXs.


I never changed from the stock gearing. With my riding I never felt the need. I never did really technical riding with this bike and I rarely worry about lifting the front over obstacles. If I was in a rocky area and needed to do that more I’d probably switch to a 13 tooth front, or to a 14/42 combo.


Maxxis quit making my beloved 6006 tire. It was a fantastic dual sport tire. The closest I’ve found is to run a Pirelli MT-21 front and a Dunlop D606 rear. Both wear well and have a round enough profile that they perform well on the road.



Mt Shuksan
This bike took me to wonderful places

The KLX205s is a great bike. It’s got tall offroad suspension that comes from the factory well sorted. Unlike my WR, there isn’t a need to immediately ship it off for upgrades. The tall saddle height lends itself well to trail riding, and the stock gearing is great in the woods. The tall sixth gear gives it enough to travel on the highway, but just barely. With my performance upgrades I could hang with traffic at 65-70 mph, but it was not comfortable for any distance.

The fuel mileage was great, I got about 60 mpg and I seem to remember about 110 miles to reserve fuel. There is an IMS larger tank available, and I’d consider it for any adventure travel. I occasionally just included the MSR bottles in my bag for long rides.

With only about 17 hp stock, it’s hard to get into too much trouble with these bikes. It’s a road motor with long service intervals and generally trouble free maintenance. I remember having to fiddle with my carb settings a bit, and when riding at altitude the bike being significantly down on power - but it never caused any huge problems.

The bike can be lowered a couple inches if you need to, but I can’t imagine wanting it any shorter.

One quirk - I never solved a hard starting problem if the bike had been sitting. If I knew it was going to be stored for more than about 4-5 days I always made sure I ran the carb dry. When I was close to home, I’d turn off the fuel petcock and drive home, then let it idle in my driveway until it died. I would then open the choke and crank it and let it finally die one last time and then store it. I never had any troubles starting after doing this. Not sure exactly what was going on.


My beloved KLX was stolen, and I later replaced it with my WR250r. I searched Craigslist for years for that bike - it never turned up.

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