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This has GOT to be the most trashed modern YZ250 I've ever seen - so I had to buy it and ressurect it from the ashes ![]()
In this thread I will be doing a frame-up restoration, including:
1. Splitting the cases and rebuilding the motor, tranny, and clutch (the left case is cracked)
2. Rebuilding the carb
3. Replacing all the bearings (wheel and suspension)
4. Swapping out the trashed plastic
5. Refurbishing the controls and cables
6. Servicing the brakes
7. Dealing with the frame
... and any other surprises that crop up!
The suspension will be sent to ProCircuit to be serviced, and the radiators will be sent to Terry Myler to be straightened, but all other work will be done by me and I'll be posting pictures and details along the way!
No part of this bike will go untouched - so for anyone interested, please check back on this thread often to see how this project is going! The goal is to take it out riding by the 1st of August.
Now here's the bike! If we're all being honest, and we saw this posted on Craig's List or eBay for $2,000 or so, many of us would be lining up to buy it. That's pretty cheap for an '06 YZ250!
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But there's evil lurking behind the battered plastics and scuffed up pipe...
Let's take a closer look at the right case.
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See the JB Weld on the bottom of the clutch cover? This bike ate a rock HARD! Now imagine all the oil pouring out, and imagine the owner riding it a few miles on a trail back to the truck - with no oil.. so, we have a trashed transmission on our hands!
Now onto the left case.. other than a missing screw at the bottom, and a lot of scrapes and dirt, all looks well, right?
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Not so fast - let's take that cover off!
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Yep - a cracked case. This is not a cover piece either, the whole side of the case will need to be replaced. Any water that will invariably get past this crack will wreck havoc with the stator, and the dirt that will get in will be none to kind to the crank seal, I can promise you that!
So let's take the plastic off and see how she REALLY looks.. !
First disappointment was the condition of the radiators -
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Not quite square anymore ![]() We'll get back to that...
At this point all the clothes needed to come off - so here's my bike, nekked..
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I took the wheels off - the knobbies were pretty worn out - and sent them over to the local shop to be fitted with Dunlop 756's front and rear.
Next comes the subrame. I don't bother stripping it at this point, I just need access to the rear suspension, and I want a closer look at the swingarm.
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Any eagle-eyed observers will also notice the rims in the background with their fresh rubber installed ![]()
One thing that makes people nervous about a project like this is keeping track of all the nuts, bolts, and fasteners... if you look at the pic below, you will notice I put practically every fastener back in the frame where it belongs, and where it won't get lost. In the pick, the rear two radiator bolts are back in the frame (after removing the radiator), and in a moment I will screw the front bolts in the frame too.
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Now that I've got some good access, off comes the forks and the rear suspension. I'll be sending these off to ProCircuit for a complete overhaul and revalve.
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In the coming days I will be pulling the motor and dealing with anything else I find.. In the meanwhile, the radiators are off to be straightened and the suspension is en-route to ProCircuit. I probably won't get back to this bike for a couple days, so to make sure I don't cause myself any more troubles, I place a rag in the exhaust port, I cover the carb mouth with a plastic bag (held on by a rubberband), and I do the same for the coolant port on the head... now the motor is sealed up until I get back to it.
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I know that reading this, it looks easy. Trust me - it isn't. If you plan on taking a bike down to the frame, be honest with yourself and give serious thought to your mechanical abilities, time and access to tools. I wouldn't even consider doing this without an impact wrech and a Service Manual, just to name a few... I think many of you can do this same job, but take it form me - it's not an easy or fast project.
UPDATE MONDAY 7/17
Well, out came the engine tonight!
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UPDATE 7-18
Ok, I pulled the top end off. Here's the left (cracked) case:
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It's going to be hard to see in the pic, but this is the inside of the cylinder. It has smooth spots and spots worn through near the exhaust port. Also, there are signs of a couple seizures. The crank, on the otherhand, is perfect! .35mm side clearance and no up-down play.
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Finally, the right case. So far, the clutch basket looks good!
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UPDATE 7-18
The clutch is out and the countershaft sprocket has been removed. The countershaft sprocket is beyond worn out...
The clutch basket looks perfect, as does the pressure plate. The clutch springs are at 50mm free length (new ones are 50mm - they are considered sacked out at 48mm). So basically we ave a flawless clutch! As with the crank, I can tell the clutch is the original. It still has the white setup paint on it Yamaha uses during assembly, whereas replacement clutches do not.
I'm going to take a break for a bit and give my back and fingers a break - soooo sore ![]()
But I'd like to take a moment and sum up the project so far:
This bike obviously has over 200 hours of hard use... not surprising. But shockingly, the motor is in darn good shape! Here's the list of action items so far:
1. Tires were totally worn out.
2. Both sprockets were worn out, as was the chain.
3. Shock and forks were long overdue for a service, however I felt no problems when I manually cycled them, so I doubt there are any broken parts - probably just worn bushings and dirty oil.
4. Every single piece of plastic including the chain slider, rear caliper guard, rear rotor guard, countershaft sprocket cover, ignition cover, and lower chain guard were either trashed or cracked.
5. The cylinder is worn. This cylinder could be re-honed and last another 40 hours, but since I've got it all torn down, i'll spring for a brand new cylinder.
6. Piston and rings could also go another 20 hours or so, but I refuse to put a worn piston and rings in a new cylinder. Topend (small) bearing and piston pin were fine, but they will be replaced with new parts.
7. Crankshaft was in unbelievably good shape! All the specs were what you'd expect to find with a new crank! Since I have to split the cases to replace the cracked left case half, I will be pressing in new bearings (end of crank) and new oil seals, just to make sure it's solid.
8. If someone handed me the clutch assembly and told me it was out of a new bike, I'd believe them! Every part was in perfect shape.
9. Waterpump was fine, but the cover gasket was not in good shape - that will be replaced.
10. Powervalve assembly looks awsesome.
11. Clutch cover was cracked and will be replaced.
12.Left side case - under the stator - was cracked, so the whole left case half will be replaced
13. Radiators were both bent, but neither was leaking - they've been shipped out to be straightened.
People ask me why I love Yamaha so much.. this bike is a perfect example why. It's been mercilessly abused - seemingly bounced off every rock in colorado - the covers are all cracked, and it clearly has a lot of hours, yet once the case covers came off, all that's showing any wear is the cylinder, and that was probably due more to operator abuse than to anything else. That's a testament to Yamaha reliability!
Final Update:
Well, it's been a while since the last installment, but this is a big one!
So let's get right to it...
The swingarm linkage was ruined - siezed with rust ![]() this is why it is sooo important to keep the pressure washer away from the swingarm, and to grease your bearings at least a couple times a season. If the previous owner had done that, these bearings (remember this is only an 06) would still be in good shape. Take a look at what's left of them.
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I went ahead and put brand new bearings and seals in the link, and also new seals in the frame where the swingarm joins up. Everything go t a good coat of grease, and back together it goes!
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My radiators showed back up from Myler's and they look awesome! Completely straightened and pressure tested for $70 - can't beat that!
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Now i'm ready to tackle the engine. First order of business is the new cylinder. I am not going to go through the step-by-step on the powervalve disassembly/reassembly, as it's covered in perfect detail in the Service Manual. What I will say is that on a Yamaha taking the powervalve off one cylinder and transferring it to another is about a 10 minute job - easy as pie!
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The cylinder head was next, and I was in for an interesting surprise!
In the pics below you can see that I have the head mounted on a lathe. One of the steps in blueprinting an engine is to 'face' or machine off a tiny amount of metal on the cylinder head base and on the face of the spark plug hole. The facing of the base ensures that the cylinder head fits perfectly on the cylinder, and the machining of the spark plug base get's rid of any burrs, so that the plug seals well. I made a jig out of 414 stainess, basically just a 3/4" piece of steel machined with 20TPI threads the same diameter as a spark plug. I use this to hold the cylinder when machining it. Here's some setup pics...
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So I took a facing cut on the spark plug hole - no problem. But when I got to the cylinder base I noticed that it was over 1mm off! All on one side.. I suspect that the cylinder head was warped from improper installation, or that it was overheated. Maybe it faulty to begin with - who knows. I could have corrected the problems on the lathe, but for $150 it's easier just to buy a new one. So I did. I trued up the new one and it just took - maybe - .01MM to get it dead on.
Now to the lower end. Some disassembly has already been done (see above) but a few more things like the flywheel, etc.. need to come off. A quick word of caution - never take a flywheel off with anything but a flywheel puller, and when you begin the project, alwayts put a dab of grease in the machined hole at the flywheel end of the crank. If you bugger this hole up it will be impossible to true the crank later.
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I ordered a new case-half, and had a friend press the bearings in (I don't have a bearing bress myself).
I'd like to show you pics of the split cases, but I don't have any to post - sorry ![]() The cranks, as stated above was in perfect shape. The bearings got replaced (only because the case half was new - they weren't worn) and while in there, I put in new seals. The tranny had chipped teeth so new parts were ordered up. While waiting for them, I got a package from ProCircuit - suspension done! 7 days turnaround, just as promised, and $350 very well spent. Now I know the suspenders are perfect and ready for another season!
Once the engine was done, everying goes back in the way it came out. I replaced any ratty screws and fasteners, cleaned up all the electrical connectors, and refurbished or replaced any worn boots or grommets.
A few things to note.. use anti-sieze on any steel bolt that will touch aluminum - this includes your base studs, cylinder studs, radiator bolts, caliper bolts, etc... it's great insurance against a stuck bolt!
So without any further ado (but several nights of back-torturing re-assembly) here's Project Phoenix!
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I didn't photograph as much of the rebuild as the teardowm, simply because re-assembly is just the reverse process. Plus, this project's deadline was looming and I had to get hustling! If anyone wants any more detail on a specific step though, just holler and I'll post it!
Project Phoenix was both gratifying and gruelling - it was a HARD build. From a cost stanpoint, I spent enought to have bought a new YZ250 - so there was no cost savings here, but from a gratification standpoint, well.. putting your hands on every nut, bolt, and fastener builds an indescribably bond between man and machine - not to mention a huge sense of pride. Phoenix now has a permanent home in my stable and will live out the rest of her years under my care!
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Here we go again!
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