2000 Kawasaki KLX300
I got this bike so my girlfriend could go riding with me. Her last bike was an XT225, and although it was a good beginner bike, it left a lot to be desired in the dirt. I was looking for a bike that was 4-stroke, easy to start, not overly powerful, watercooled, affordable, and relatively light.
The only bike I found that fit the bill was the KLX300. I looked at a few spanked ones before I found this one. I drove so far to look at it, I wasn't about to go home empty handed. The second owner was the seller's wife, the first owner beat it up a bit.
The KLX300 is a good beginner and trail bike. It's easy to start, and has fairly forgiving mushy suspension. With more power and better suspension, it hold its own much better. One of its largest shortcomings is the Mikuni CVK carburetor. The vacuum slide CVK is ok for a streetbike, and is even alright in the KLR650, but it has no place in a dirt-specific bike. The throttle response just isn't there, and when you're heading straight for a ditch, you want snappy throttle response. See below for the carb swap.
The KLX300 has two major achillies tendons: the KACR timing, and the valves. You wouldn't expect the latter on an engine that's not especially high strung or high powered, but the KLX300 has a tendency to "mushroom out" the intake valves. This causes them to sink into the seat, and the valve clearance eventually goes to zero. The previous owner had this problem, and supposedly replaced them before I got the bike. They were fine when I had the head off, but we'll see how the next valve adjustment goes.
ACR Retiming
This is probably the most important mod for a '97-'02? KLX300. Kawasaki's auto decompression (KACR) uses a spring loaded centrifugal mechanism at the end of the cam, which opens one of the exhaust valves slightly at low rpms. The only problem is that for the '97 to around '02 KLX300s, the ACR was timed improperly from the factory. This leads to harder kicking, and stresses components like the idler gear, which has been known to shatter.
There are a few options here. First is to leave things as-is, kick it like a big-bore, and wait for something to blow up. Not so good. The second is to buy an entire exhaust cam assembly from Kawasaki for an '03 or newer bike. The third option is to press out the ACR assembly and reorient it. Or better yet, find someone else who has done it before and has the fixturing for it. I found a nice guy on Thumpertalk who did it for me.
With the ACR properly timed, the bike starting procedure goes as stated in the manual. Slowly kick over until resistance is felt, go a little past TDC, and give a firm, even kick. You should be able to start it with your hand if the ACR is doing its job properly. It will feel like kicking over a 50.
Pumper Carb Swap
There are a few carb swap options: the most common being the Keihin FCR35, and the Mikuni TM33-8012 and TM36-68 (the -8012 and -68 mean that they have an acclerator pump). I was concerned about the FCR35 and TM33 requiring the removal of the push throttle cable to fit in the frame (TM carbs actually come with a tag warning that the push cable is required in case the throttle gets stuck open. The TM36 is almost a drop-in swap. The airbox needs to be spaced forward a little bit, and the tank needs to be shimmed up, but the inlet and outlet of the carb is the same diameter as the CV. Just like the FCR, the AP on the TM36 benefits from being wired. Unfortunately due to the AP linkage, wiring it also causes the rod to become bent. I'm in the process of working this one out.
When I say almost a drop in swap, I mean that the throttle cables have to be re-routed, the airbox needs to be spaced about 1/4" towards the engine, the tank needs to be raised up to clear the top of the carb, and the petcock and throttle pulley need to be clearanced a bit to clear each other.
Before the swap, I thought I'd never have to change the rear tire. One ride with the TM and I now see otherwise.
Swingarm Finishing
I'm not a big fan of painted swingarms. They often have black primer that shows through when they get dinged. The swingarm on the 300 was a bit dinged up and had a scar from where the kickstand had hit it in a crash (since removed). I started cleaning it up, and figured why not brush the whole thing. It's a messy job that requires a lot of pressure. I found that the most effective and best finishing setup was a wire wheel on my 8A drill. It's not high speed, but with 2 handles I was able to really lean into it and get it done. it came out pretty nicely.
Airbox Modifications
The bike comes with a silly bolted-on restrictor cap on the muffler, and a lid with a snorkel on the airbox. When I got the bike, the exhaust restrictor had been removed, the airbox lid was gone, and the jets had been done. The airbox opening was still a little tight getting the filter in and out, and I wasn't planning on using the lid, so I cut some of the extra plastic off the top. It's a lot easier to get the filter in and out now, and it breaths better too.
Guards
Same combination as the 450 for the radiator: Works Connection braces and MSR guards.
I also put on a Works Connection rear caliper guard and replaced the stock chain slider with an MSR one (Fredette Racing). The bike came with a skid plate, a water pump guard, and MSR handguards. All this adds up to a bike pretty well protected against frequent spills.