When I bought this KX125 I took it completely apart to sand blast the frame and go through everything. My son claimed it; as soon as I would have it back together he was going to take it with him. When he died I just lost interest in it for a little over a year. This past summer I decided to put it back together without doing all the work I had planned on doing for my son; I wasn't going to do all that for me.
I replaced everything that could wear in the forks and the fork caps. Whoever had the bike before me had stripped the compression adjustment on both fork caps. While on the front end I replaced the wheel bearings and cleaned and repacked the steering stem bearings. I replaced the fork oil with the same weight oil I used for my XR, 10 weight, but that was a mistake. It rode like a jackhammer in the front. I checked on Race Tech's web site and found what the right weight, 2.5 weight, and height was for the fork oil. The bike was still riding a little stiff for me with the correct height and weight oil so I lowered the oil height just a little, about 1/4", and now it rides great.
My original plans were to powder coat the frame but I decided just to paint it once it was sandblasted. I did powder coat the swingarm and everything that is red on the bike. I need to make an oven large enough to bake a frame in so that I can powdercoat larger items. I have seen on powdercoat websites where heat lamps can be use but I think it would be very difficult to get a good even flow on all the sides of something as intricate as a frame. Powder Coat link Powder Coat link
I replaced all of the seals and gaskets in the engine and sent the cylinder to US Chrome for stripping and replating. My original intentions were to split the case and powdercoat all of the engine in translucent red. I would have done that for my son but not for myself so only parts of it are powdercoated. While I had the cylinder off I did some minor porting to it, mostly just smoothing out the ports.
I replaced all the bearings in the rear suspension and rear wheel. All of the old bearings were shot. Some were rusted beyond any ability to work and the wheel bearings were almost non existent. The bike received all new cables, throttle and clutch. A new chain and sprockets were also in order along with swing arm proctor and rollers.
After it was all said and done I am well pleased with the bike. It had a Dyno Port exhaust system on it when I bought it and that seems to be a really good combination. I had a local machine shop machine a flywheel weight for me that turned out to weigh 10.4 oz. It has really helped in the extreme twisties we sometimes encounter down here in Louisiana and it still rips on the straits. I have ordered a spark arrestor silencer from Dyno Port and am awaiting deliver of that at this time.
I would like to take the wheels apart and replace all the rusted spokes and anodize the aluminum wheels. It is a fairly simple process to anodize your own parts. I would also like to do my own electro plating of the nuts and bolts.
New 11/21/03 The old KX is DOA. When riding at Claiborne I rounded a corner that had three trails to chose from, two were right and one was wrong. You guessed it, I choose the wrong one and ended up with water in the engine. We got it cranked after draining all the water out but the ride back to the truck took a toll on the ring.
Back at home I removed the engine from the frame and cleaned it out with premix. I took the carburetor apart to clean it, washed the air box and serviced the filter. A new ring had it running like it should. I made a couple more rides of 50-60 miles each then while riding at Red Dirt the engine went south on me. I wasn't far from the truck so the walk back wasn't too bad and I was able to drive right up to the bike to pick it up. When I dismantled the top end there was a small piece of hardened steel stuck in the head that appeared to be from a bearing cage. I have bought all new bearings and seals for the engine and have sent the crank to be rebuilt. I am now waiting for all the parts to return.
While waiting for the parts to return I have begun bead blasting the case in preparation for powder coating.
The crankshaft has been rebuilt and a "Hot Rods" rod installed. I have replaced every bearing and seal in the engine, again, and the beast is running again. I installed a silencer from Dyno Port that has a spark arrestor and I cannot see where it has made any difference in performance. Neither has it made much of a difference in the sound; it is still pretty loud when it is on the pipe. I was hoping it wouldn't slow the performance down but that it would quieten the bike some.
I installed a carbon fiber ignition cover because the old factory cover looked bad and I had to remove the flywheel weight because it would not fit under the carbon fiber cover. I have not ridden it on any trails since then but I hope it performs well in the tight stuff without the flywheel weight. I am looking at buying a friends KDX 220 and selling both my XR and KX. The KDX is made more for the woods and the XR is too heavy for me after riding the KX. The KDX I am looking at is 20 pounds lighter than my XR but not as light as the KX.