Posts
3558
Joined
5/25/2014
Location
San Diego, CA, USA
Edited Date/Time
1/6/2023 9:46pm
Welp, time for another project. 2003 YZ 125 in pretty rough shape. Cylinder is trashed so I know right away I'm going to go with a big bore seeing as how I would have to get the cylinder replated anyway. Might as well! Here is our starting point. 
I'm slowly collecting parts for my 98 YZ250 but plan on using SSS forks, Fox Podium shock, 09 YZ450 swingarm and the correct rear brake/wheel setup. Plastic will be a mix of new look and old look but that could change. You have the same choices including the full 2023 plastic option depending on your budget. It's very cool to have a bike that has pretty much had the same platform from 98-23 and Yamaha has always been great at being a parts bin company which makes for lots of options.
I see you have the cracked exhaust bridge that was common with those models. Rumor has always been the 98 cylinder was the best for mid/top power but to use that cylinder you would need to run an older exhaust as they switch flange styles in either 99 or 00. I built an 01 with 98 cylinder and original Bill Pipe setup and it was a mid/top ripper for sure.
Looking forward to the build.
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Historically I have had very poor luck with painting but I have only ever used a rattle can. This time I picked up a basic touch up gun, watched a bunch of YouTube tutorials and then asked a bunch of dumb questions at the local paint shop.
Lo Brow spray booth setup in the shed. Sanded and primed and I will shoot color later this week and hopefully clear next week. I also laid down some beads in those areas of the frame, like the motor mount tabs, that just seem to collect moisture. Not for structural reasons but more for smoothing that gap where mud always seems to collect.
If I were to do a frame again I think I would make some sort of rotisserie to hold the frame that I could rotate and get into all the nooks and crannies and see things well. I have definitely laid down a coat and then looked at it and realized and missed a couple spots that I had to make sure I got on the next coat. Things like that.
But I am very, very pleasantly surprised with how well this is coming out. A decent little spray gun, (I just bought some used $30 cheapy off of eBay) keeping things clean and some quality products is looking like it will lend some pretty decent results.
I should be able to finish the last coat of clear today.
An example of an area I missed and went "D'Ohhhh!"
Yeah, it was a three part primer, two part color and two part clear. Reminded me of my
surfing days fixing dings and mixing resins and stuff. But this time I was wearing a
proper paint respirator mask! hahahah
I have already located a matched set in excellent condition on eBay though it does cut into the budget significantly. On the bright side, the rest of the bottom end is absolutely perfect. The transmission, shift forks clutch and everything are absolutely primo and as an added bonus there is a complete Hinson Billet clutch installed. Oh well, part of the process in these rescue projects.
Carry on, you got this.
Pit Row
I know some people have had some communication issues but here is how it went with me- Email, nothing. Text, nothing. Called- picked up second ring and we talked for about 10 minutes and he answered all my questions. (I had read his website and all the FAQs so I did not bug him with redundant questions.) When I mentioned how trashed the cylinder was, he said (paraphrasing)- "Yeah, we fix those all the time when we get a batch together. I'll exchange yours for one I already have done on the shelf."
Bore, plate, trim exhaust valves, beef up exhaust port bridge, grind the cases to accept the big bore, cut the head, (you tell him what fuel you'll be running and what sort of riding.) Piston kit, including spare ring. Does not include gaskets but it maintains the OEM gaskets, which I like. He quoted me "About three weeks" to have it done.
Packed everything up and chose the prepay option ($475), which speeds things up for return shipping. Enclosed the check and shipped it out.
TWO WEEKS later, the box is back at my front door. Holy fugg, that was fast! I'm calling this a very good deal and am very satisfied.
We have had many pleasant experiences with Eric Gorr for years. My grandpa used to do business a lot with him, then my dad, and now me too. He has always been quick about turning around our orders and his prices are very reasonable. And yes, calling him seems to be the best option lol.
I’ve read that the 134cc build is very good in these, and keeps the 125 power curve, just more power everywhere.
Wheel lacing day. As we know, anti-seize is one of the messiest substances on earth. Merely removing the cap ensures that it will not only get on every tool in your garage but be tracked into the house and all over the kitchen for the next week. So this time I put just a tiny squeeze into the spoke nipple first as opposed to putting it on the threads of the spoke . This might be old news to some of you guys but was a lot cleaner way of doing it for me.
I use hydraulic oil for truing. Way less of a mess.
Sweet build. I'll be following as I'm currently rebuilding an 06.
Any reason for not going to TMR again? I'm about to ship my stuff to him for a 144 kit.
Quicker turnaround, to try out a different builder, (I feel good about the quality of Eric's work) and fit my budget better. (I'm over as it is! hahahaha)
Today was case cleaning day. The jacked up part about this process is you will clean one area of the cases and then realize the spot next to it looks like crap. So you clean that and then it just dominos. Then you realize you missed a spot, go over it and then that one comes out too nice so you have to clean the areas around it. Next thing you know, hours and hours have gone by and it is much shinier than you ever would have planned on. Hahaha.
Getting around to some assembly. This is the part where no matter how well I organize things, and I'm pretty organized, I'll realize I forgot to order a part or something, or worse, thought I hadn't ordered a part when in fact I did, so now I have an extra and my wallet has a bigger hole.
Anyway, some good, some ugly. Scored a 280mm EBC front rotor and bracket open box new for about $150. But then used these dog shit Bolt bolts. What garbage. Terrible finish and soft like butter. They started deforming at the sight of the allen wrench. They will be getting replaced.
In the past, I've used those Nickel Wurks bolts from Spec Bolt. And while I think they are a good value, they do start to show corrosion after a while. So this time I got a stainless bolt kit for the motor. Good price, complete with everything. Put things together with a little anti-seize on all the threads. Then I got to the acorn head bolts . . . 13mm?! WTF! Seriously? Do they know this is a Yamaha and not a KTM? I was pissed for a bit but then had an espresso, clamped them in the mill and kissed .5mm off all the flats and voila! 12mm head bolts.
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