I Rebuilt My YZ125 In A Closet!?

It was more like a hallway, but the work area was still smaller than I wanted. I picked up a 2003 Yamaha YZ125 that had some major frame damage. The bike ran well but was not ride-able. The two options were to scrap the main and sub-frame, or take the time to bend and weld them back to their somewhat original form. Either way I would have to strip the entire bike down to the very last bolt and tie-strap. Just by looking at it I could tell this was going to be a difficult, yet exciting project.

I got to work tearing down everything on the YZ125, starting with taking the engine out of the frame. There were a lot of nuts and bolts from the plastics, engine, radiators, frame, and other miscellaneous parts that I had to organize into little zip-lock bags so I wouldn’t lose track of where they went when I put them back on the bike. In the middle of this process I got the sub-frame bent back and welded so that it would fit like normal. Being me, I decided to go the more challenging route of getting the main frame welded instead of paying a couple hundred for another one. Once I took everything off of the main frame my dad helped me by welding it.

I wanted to make this bike look good when it was finished, so I sanded and cleaned off the main frame to get it ready for painting. It took a while, but I managed to find some paint that was close to stock color shade. I then painted it with a few coats to make sure that it wouldn’t peel or chip right away.

Tear Down Process
Tear Down Process

The rebuilding process began just after the paint on the frame dried. This is the part where I had to move everything inside…. I started with the foot-pegs, front-end, rear shock, and swing-arm. Those went on pretty easily, so I then took the whole engine and bolted it up to the frame. The rear-wheel and handlebars with controls were next to go on. After that it was just the electronics, carburetor, plastics/tanks, seat, and a few miscellaneous things, such as the exhaust system.

Rebuild Process - Frame painted, front-end, rear shock, and swing-arm on
Rebuild Process - Frame painted, front-end, rear shock, and swing-arm on
Rebuild Process - Engine in, rear-wheel, handlebars on
Rebuild Process - Engine in, rear-wheel, handlebars, and controls starting to go on

After working inside for some time, this project was well worth the outcome. In the end I think the bike looks good, and I learned quite a bit more about rebuilding these modern dirt bikes (Check out my other article, “How I Built A YZ250F With A Box of Scraps” if you liked this one). Let me know what you think, and if you want to see more projects like this just give me a shout. Thanks!

-Tom Stark

Finished '03 YZ125 Project
Finished '03 YZ125 Project

What Is The Most Reliable 250F Dirt Bike?

A very common question asked by new riders or people that have never owned a 250 four-stroke motocross machine. First of all, it depends on what year dirt bike you are looking at. 250F’s rapidly changed from the first years until now, and many of them had problems that needed to be solved.

250F Motocross Bikes

Although the manufacturer’s had problems with their high-performance quarter-liter four-strokes, Yamaha pretty much had it figured out from the beginning. They were the first to come out with a 250cc 4-stroke motocross bike (YZ250F) in 2001, which is 3 years before any other manufacturer’s got on the band-wagon.

Yamaha’s YZ 250F become an instant success once riders started winning on them. In 2001 and 2002 the bike came with manual-decompression, making it a task to start the bike at times. But the only real problem the bike has ever had was in ’01 with a weak crankshaft that would go out on some bikes. In 2003 the Yamaha 250F came automatic-decompression. Up until 2006 the bike had no problems. The ’06 YZF did have a valve problem, but Yamaha recalled every one of them that was sent in. Riders that have had or been around 250F’s know that Yamaha was always the most reliable in the early years, even if it wasn’t the most powerful.

2004-2006 were embarrassing years for the other manufacturer’s. Kawazuki’s KXF/RMZ250 was a nightmare on wheels, especially when not properly maintained. Honda’s CRF250R often ate valves like Americans eat McDonald’s grease burger’s. By ’07 the companies (excluding Yamaha) started figuring out the kinks in their 250F’s….

If you are looking to get a 2008 or newer 250F and are deciding based on reliability, just pick a color. Really, pretty much all 250F’s now are reliable IF, AND ONLY IF, you take care of them. Doing regular maintenance on a 250 four-stroke is very crucial and will make them last much longer. There’s no reason why you shouldn’t be able to get 50+ hours on a stock top-end, as long as you aren’t Pro or riding it on the limiter all day long.

Maintenance means changing your oil every 5 hours or so (oil filter every other oil change), cleaning your air filter every 1-2 rides, believe it or not cleaning your bike will make it last longer, lubing and cleaning your chain every ride, and re-greasing the bearings 1-2 times a year. There are a few more things you should do, but just doing these simple things will allow you to ride your 250F much, much longer.

250F Motocross Bikes

As soon as you get the key maintenance steps down, there are just a few things left to do to make sure your dirt bike stays in tip-top shape. It is extremely important to keep the valve-train in good running order. To be sure of this, the valve clearances should be checked at least once a year (every 15-20 hours of ride time to be safe). Contrary to what most people think, the cam/timing chain should be replaced with a new one every year. If the chain breaks or seizes, the valves also seize and will be hit by the piston, causing massive damage to the engine. Buying a new timing chain is cheap insurance, so keep that in mind. I will get more into these topics in future articles.

Other than doing the normal maintenance, choosing the right bike mostly depends on its history. If you’re buying a new 250F then it’s no big deal, but buying a nice used one can be difficult. A good bike to buy is one that is clean, has low hours, was properly maintained, and the owner isn’t trying to hide anything.

Take your 250F’s to the track with a Dirt Bike Carrier.

Good luck, and remember that maintenance is more important than anything on a 250cc 4 stroke motocross bike!

-Tom Stark

My Supercross Race

Jordan Supercross Race 6-26-09

Just had another supercross race last night…. It was an absolutely perfect night. The weather was warm and sunny, the track conditions couldn’t have been better. Plus, my class had the most entries. There were about 24 or 25 riders, which is a lot for a supercross track. I was riding my ’01 yz125. The first moto I pulled a pretty good start against almost a full gate of 250f’s. I ended up about 5th or 6th out of the first turn. The whoop section was next, and I have not conquered the whoops yet, so I got passed by about 5-6 riders right away. I was doing pretty well until about the third lap where there was a 180 degree turn where there was big roller just before it. Well what I didn’t notice was that there was a rider down right after the roller. I didn’t see him until I rode over his bike and fell over. I finally remounted and got going again after another 5 riders passed me, but what makes me even more upset is that there was no flagger there to wave it off. But oh well, it’s racing. I ended up getting about 19th. When the main event came I had a really bad gate because I was almost the last to choose. I ended up about 15th after the first turn. Once that mess was over I cruised, and cruised fast. I passed one or two riders and ended up about mid-pack I think, didn’t get a chance to see the results. Over all the race was great, and I had a lot of fun. Not to mention I didn’t get hurt!! My next race will be in about two weeks, so I’ll be ready of that. Thanks for reading, and I hope to post more soon!

-Tom Stark

Click here if you want to start racing!

KX250F & RMZ250 2004

2004 Kawasaki & Suzuki 250F

2004 RMZ250

If you’re looking at getting an older 250f, and possibly a Kawasaki or Suzuki, then you should probably consider some of this info. When these companies made their 250f, it was more like a Kawazuki 250f, because Kawasaki and Suzuki had partnered up. So most of the parts on these bikes are interchangeable. This was their first year making the 250f, so just by that you should be a little worried.

2004 KX250F

As some might expect, these bikes were not the greatest reliability-wise in 2004. Although they were fast bikes, they had an overheating problem caused by a bad/weak water-pump. Another defect these bikes had was in the valve-train that caused the valves to burn-up more quickly. These problems can get bad and scared me away from buying one of these bikes. This is not to say that these bikes do not perform. They have plenty of power, and if you really want to get one then I suggest you get a newer style complete cylinder head and get and aftermarket water-pump and impeller to fix the overheating problem. If you do that then the bike should be fine, but by the time you spend all that money on parts you could have bought a newer bike more than likely. Good luck, and remember that no matter what you ride, have fun and stay safe! Thanks

-Tom Stark


So You Think You Know How To Ride A Motocross Bike…

A lot of people hop on a dirt bike (usually one that’s too big/fast for them), rip down the street once, then say that they’ve “Ridden” one… Well, that’s what I call a hot-headed Poser. They prance around, boasting that they owned the sport of dirt biking, and it’s on to the next “sport”….. This is why too many people say that “Motocross is easy”, even though they have no idea what the actual meaning of Motocross is. In their minds, riding a dirt bike is motocross, so they tried the sport of motocross when they took a bike for a spin down their neighborhood street.

Motocross Goons

Let me tell you something; a myth that most people (even riders) con themselves into. It’s that the bigger and more powerful bike you have, the faster you will go. In a straight line drag-race, yes, but who can’t ride a straight line? How about on the track, where the real athletes are? Yeah, the torque of a 450cc 4-stroke does make it easier to clear that step-up right after the corner, but it doesn’t necessarily make your lap times lower. More on this later…

I can go through all the gears on my 125cc motocross bikes. Or a 500cc for that matter. If you can’t do that, then you probably don’t belong on a motorcycle. Doing it on the street is one thing. Doing it on the track… Not even comparable. It takes more skill, strength, and endurance to ride on a real motocross track than almost any other sport, and injuries are more so common in this sport that you can almost anticipate one in the future. That’s why it’s a good idea to Get Insurance for Motocross Racing. The top riders in the world are in better shape than 99.9% of athletes. They train harder, longer, and more, as well as practice on their bike (which is more of a workout in itself than many athletes do). Although, the average Joe would have no idea, whether they’ve “ridden” a bike before or not.

Real Motocross Riders

I know plenty of people that don’t think motocross is very difficult to participate in. It’s understandable to an extent, because they just don’t know; and probably never will. It’s not something that you can explain either, especially if they play other sports or activities (such as soccer). They often have it in their mind that the sport they do is more straining on the body than others. I’m not saying that you should try and convince them either. Most of them are too stuck up anyway if they believe anyone can race motocross and have success.

Back to the lap times… It doesn’t take a 450cc motocross bike to get the fastest lap times, even though it may help in some areas. Motocross is about 90% rider and 10% bike. Although some may beg to differ, just look at what James Stewart did on an “old and outdated” KX125 2-stroke. This is why I believe a 125 2-stroke is enough power for 99% of riders. Now, one exception is rider size/weight, as some larger guys will do better on a bigger bike because they need more torque to get going. My argument¬† is, if you can’t ride a bike to its full potential, why go bigger? I would personally consider riding 85’s because of my size, but the only adult classes (other than pit bikes) are with full-size bikes. (This is why I’m building an XR100/Motocross Conversion bike over the winter as a play bike, which I’ll cover on a future article…)

So, the act of actually knowing how to and riding a motocross bike is by racing as fast as you can for a certain amount of laps around a motocross track with real jumps, corners, whoops, ruts, braking bumps, natural terrain, etc. (not down your road or a corn field).

-Tom Stark