Hey guys, this will be more of an informative build, rather than a full tilt build thread. Back to the two stroke basics, might as well keep it pretty simple. I am coming off a YZ 250. Always wanted to ride an aluminum frame YZ 125, but never had the chance. The bike is in pretty decent shape, not many hours on it, but it was neglected. This thread will be picture heavy. Everybody is more than welcome to follow us on Instagram https://www.instagram.com/btisport.team/.
Here are the pics of the Facebook ad.
The not so good, (but expected anyways).
After a wash and some love, she is looking more promising.
One thing I noticed when I picked it up, was that when idling, it was a bit noise. So we suspected the piston size is too small for the cylinder bore. We then took it apart. Holy carbon build up batman! Keep in mind the seller said it had 7 hours since last rebuild; bike was waay too rich, but I prefer that, rather than having to deal with detonation and lean scenarios.
Now the fun begins, can you guys guess wether or not the pivot shaft came out easily? More on than on the next post. Cheers!
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That radiator repair is top notch!
So as it was expected... the pivot shaft was welded. We didn't want to hammer it much, so in the press we go.
And here is what the pivot bearings looked like. Funny thing is, the seller was reluctant to lower the price, as he stated "you are not gonna find a bike like this, don't even bother looking for" LOL.
We did a fork rebuild, installed Factory Connection springs for my weight and skill, and some Zeta free pistons, as the stock one were broken (glad I had these leftover from my 250). I am intrigued as to why somebody would install push bleeders, but never even push them!
We always install an o'ring, as a cheap way to record suspension travel (the right thing to do is install a WP fork travel ring, but this serves the same purpose).
We measured the cylinder, it's a 54.025 bore, so it needs a D piston. Glad we tore it apart.
Huge thanks to a friend of mine who has a machine shop, and measured it with an inner micrometer, a little bit more precise than my gauges.
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Nice work so far. Big fan of the budget/minimalist builds.
Well not much progress, took the tires off, and cleaned the airbox.
Quite needed change lol.
We are mounting a MX53 front tire, and a MX 33 rear (I haven't bought a 100 rear tire in like 10 years!).
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Talk about a before and after.
The swingarm was in pretty good shape, while I am at it I will throw some new adjuster nuts.
Nice build and details.
Maybe I can organize myself, my shop, and my 2000 RM 125 build enough to do the same!
Keep up the good work!
May as well send the head and cylinder off to have a little port and polish work done…I always think it helps the 125’s run crisp and clean the way they should!
+1 on porting it. Just clean up the intake. It helps a lot on YZ125s.
At a minimum get the head cut for the fuel you intend on running. Port it if you got a few extra dollars to spend. Getting the head cut and properly dialed jetting goes a long way when done correctly.
100% agreed.
Thanks for the suggestions guys! I might get the head milled ( I had an Apex head on my old 250, and it was definitely worth it).
Tires mounted up and ready to go.
Lucky for me I have a great friend that is a proficient tig welder and fabricator, so I had him repair both the radiator and the rear chain guide.
In the meantime we did a shock rebuild. It was low on nitrogen, hence why it had so much cavitation.
We cleaned the plastics a bit, ready for a set of graphics (but I will just ride it without, more on than later). They turned out pretty good.
Ahhh I love a nice yz125 build of this gen.
A near perfect motorcycle. I love working on them.
To marketplace!
Hell yeah, I love me an aluminum YZ125! I had an '05 and it was wonderful. That's as flickable as any Yamaha will ever be. Following.
So guys, the bike is finished for now. Took it for a spin last weekend, it ran quite funny all the way to 1/2 throttle, so we changed the clip position and now it is much better.
Backstory, I sold my LOVED YZ 250 in March, and didn't have a bike to ride. A good friend of mine who works 6 months abroad per year, told me that he wanted to get into riding, so I recommended to him getting a YZ 125. A couple of messages after, we decided that it was a great idea that I would buy a YZ, so I can ride and do all the maintenance/replace all worn parts (which is expected when buying a 13 year old bike), and when he returns, this bike will be his. I just wanted him to skip all the headaches of buying a bike and not being able to ride because you have to wrench on it (been there, done that) and it was a cool little project here in my shop. So for now it will have no graphics, but as soon as it is his bike, I will post the finished product. We also plan on throwing on an FMF pipe and a clutch cover.
It was cool to "build" a bike as if it was for me, but knowing that soon it will be my best friend who will be riding it, and it will be his first motocross bike ever!
Here is my previous bike, don't want to get into details but I had to let it go; it simply wasn't meant to be.... but this was the best bike I have ever ridden and the one that made me the happiest. We will see what the Lord has in store for me in the future.
STILL SMOKIN'!!!!!!
SWEEEEET!
Alright guys now it is almost complete! We installed a Hinson clutch cover, it really makes a difference.
We bought a brand new FMF Fatty and Shorty silencer, but sadly it was for an older model.
Finally it got some graphics. Crazy to think that after each wash, it looks much closer to brand new than before.
We found a YZ 250 Powercore II for cheap (I thought they had different diameters, but apparently not) that we will turn into a Shorty. We are pretty sure it is indeed from a YZ 250, as the 125 version doesn't have 2 mounting points, but only one.
My friend is still trying to get in tune with the bike, but for being his first time ever on a MX Bike, he is doing fine. BTW, last weekend we went to a sand track, ideal for a beginner LOL.
Stay tuned for more.
What does everyone think?!
I think awesome!
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