2002 YZ250F Restoration

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3/15/2017 8:12 AM
Edited Date/Time: 9/7/2017 5:40 PM

Let first say that I have seen some amazing builds on this forum. You guys have some serious skills and I can't compete. I'm not replating hardware in my kitchen or lathing my hubs, etc... But I enjoy refurbishing bikes to look original and for several years now I have challenged myself to not end up with more money in the bike that its worth. The last 4 bikes I did turned out great and I didn't lose money on any of them, but they were all two strokes.

This one is becoming a serious challenge. I've never dug this deep into a 250F or 450F before, and this bike was as bad as I've seen.

I paid $200 for this bike, it was missing several items including the header pipe, valve cover, cam caps, airfilter and cage, bolts, etc... It was sitting in a barn with mice living in the cylinder, in the airbox and inside the swingarm. The tires, suspension, brakes, body, engine - everything was shot. I spent about a year putting together a price list, unsure if I could even fix this without losing my azz. But alas, it appeared doable, and I was up for the challenge so here we go:

This is exactly how I bought the bike in May 2015. It came with 3 new Yamaha intake valves, a set of 2003+ stock cams with built in decompressors, a good 2005 ish bare cylinder head and what appeared to be a new cylinder and piston (with mice turds all over em smile)
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I got a junk YZ head from ebay and stole the cam caps, bolts and some other doo-dads. Here I am checking my tolerances and carefully clearancing the journals so that the cams wouldn't lock up at 7 ft-lbs.
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Evo came through with some nice OEM style graphics. Some of those stickers are original since they are still cheap at the parts counter (5-valve and fender logos). CEET did a nice replica cover and the tall soft seat foam since I plan on keeping this bike and riding it and I happen to be tall.
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Starting to peel parts off
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The radiator braces were a nice discovery. I will probably keep them on when it goes together.
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Front wheel cleaned up nice. I had to helicoil a rotor bolt hole and buy new rotor bolts since they were trashed. New tire installed, tried to clean up the wheel bearings but they are shot and need replaced.
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Ahh victory. Now we are making progress!
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Some parts starting to show up. The 2011 OEM clutch perch will be welcomed on this bike, since I have room to move the hotstart up onto the bars due to the 2003 decompressor cams I will be using. The sprocket was donated by a friend who took pity on my build smile Its used, but not much.
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Swingarm looked horrible and was full of mice nesting since the swingarm caps are missing. I simply could not afford powdercoat and krylon won't hold up. I spent several days stripping that stubborn OEM paint and getting a nice natural finish. The pivot bearings cleaned up great and will be reused.
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If anyone remembers my 1992 YZ250 build, I sanded my azz off trying to refinish all that plastic. Luckily the plastic on this bike was ALL the wrong color, so I took the easy way out and bought all new Polisport plastic. This front brake cover was missing though, so I got a scabby piece from Ebay for cheap and refinished it.
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Forks were shot. These KYB 46mm bumper forks seam to always have broken bumpers. I couldn't understand using the same inadequate OEM parts, so I found some poly ball joint covers at Autozone that fit in there nicely. I also used Yamaha OEM bushes and seals in the rebuild
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The shock wasn't blown, but I rebuilt it anyway. Here I am bleeding the air. I also have a nitrogen tank now so filling it at 175 psi doesn't cost me $10 at the shop now (yeah, I'm pretty cheap).
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I did not cut corners on the frame. I paid a local guy to blast and powdercoat it along with the shock spring. The color isn't spot on, but looks really good. I spent a few bucks at the carwash filling the dipstick tube with pressurized water and ran that clear hose out the drain. I watched all the media and gunk flow out until it was nice and clean.
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Here are clean parts ready to go! Steering stem bearing got reused. The linkage did too! I had to drive the frozen bolts out of the linkage with a big ole hammer, and the bearings still cleaned up! Those axle blocks were blue anodized at one point, had to strip em down to look more original.
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Front brakes were a mess. Missing parts, janky brake line, blown master cylinder, missing brackets. Its all back together with new pads and works great.
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The radiators have seen better days. The inner rows are a bit tweaked (probably why someone installed braces). I went through and straightened very fin that I could. You can see the difference:
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And we got a roller! I'm tall, so I'm using some bar adapters and a used set of 1-1/8th bars I had laying around.
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Here is the engine. I think I have enough parts to get going on it soon. I had to buy the timing side crank half new from Yamama for $120. I'll press a new Wossner rod on, install some new crank bearings and reuse the cylinder and piston that came with it which looks like stock bore, stock compression brand new parts. The cylinder head will be cobbled together with used parts, but the timing chain and guides and stuff will all be new.
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Here are a couple recent videos. I've got a few more if anyone cares to poke around my youtube channel.




THANKS PHOTOBUCKET FOR BOMBING OUT MY THREAD!!! I moved everything over to Imgur so we are back in business!
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3/15/2017 5:20 PM

Awesome man. It looks great. It doesnt take an unlimited budget and factory one off parts to have a nice bike. As i get older i appreciate the stock restorations more and more

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3/15/2017 7:46 PM

The 02 yz250f was the first new bike I ever bought and my favorite one I've owned.

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3/16/2017 9:14 PM

Great job!

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9/7/2017 2:30 PM

I got sidetracked all spring and summer, but I've started working on this bike again. Photobucket totally screwed this thread up and I had to move all my pictures over to Imgur in order to save it. I'll be adding to it in the coming weeks/months.

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9/7/2017 2:56 PM

super job

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9/7/2017 7:27 PM

Good looking processing sir

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9/28/2017 10:28 PM

First fourstroke I owen. Loved that bike and my brother still has it. Nice job

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10/2/2017 8:09 PM

I'm still blown away by your elbow grease on those plastics. Looking forward to seeing the final build.

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10/4/2017 10:56 AM

Do you have a part # on those poly ball joint covers?

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10/5/2017 6:41 AM

I don't have the number. They were sitting on the shelf though, so they must be somewhat universal. The center hole was a tight fit, but otherwise they fit alright. Next time I'm at Autozone I'll see if they restocked that section and try to get a number for you.

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10/5/2017 7:29 AM

Thanks.

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10/6/2017 8:39 AM

Bike looks fantastic! Do you have any advice for cleaning up the rotors? Your wheels look so nice, I can't believe they're not new. Any tips apart from scotch bright the rims + lots of elbow grease?

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

10/6/2017 2:26 PM

Thanks. I hand sand the rotors to even out the finish. As for wheels, hubs, cast metal stuff - mineral spirits is your friend! I'm itching to get back to this, but so far all I've done is clean the seat an install my new foam and cover, which I don't even have pics of yet.

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10/6/2017 3:36 PM

Micahdogg wrote:

Thanks. I hand sand the rotors to even out the finish. As for wheels, hubs, cast metal stuff - mineral spirits is your friend! I'm itching to get back to this, but so far all I've done is clean the seat an install my new foam and cover, which I don't even have pics of yet.

You used sand paper on the rotors or you sand blasted the rotors to clean and even out the finish?
You use scotch bright with mineral spirits? I've never heard of that, but will give it a try.
I have a 2006 YZ125 which is dirty all over, so I am just staring out and appreciate all these threads. All I've done so far is a first attempt with an SOS at the bare frame, but I have much more work to go, as it's still marked around the swingarm pivot and inside the cast sections.


I love the fact that this build is practical, from a cost perspective, while staying relatively true to OEM colors and parts. Just don't spoil it with any Torc1 racing stuff, mkay.

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KTM250SX YZ125 YZ85 PW80 ZX6 FZX700

10/6/2017 4:58 PM
Edited Date/Time: 10/6/2017 4:59 PM

I did get some pics of the seat. It cleaned up really nice. I really blew the budget here - nearly $100 extra bucks on tall/soft CEET foam and their best crack at a OEM seat cover. Color isn't as good as I would like, but I'm hopeful it will all look good in the end. Also found a nice nearly new bar pad laying in the garage.

As for the practicality...yeah I'll have under $2000 in this thing.

Ignore the scabby tank, I'm still working on it.

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10/7/2017 8:31 AM

Mx814 wrote:

Do you have a part # on those poly ball joint covers?

$6.99 on the shelf at my local AutoZone.

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10/7/2017 9:44 AM

Wow, after seeing what you've done so far I think we are confident you've definitely got the skills to bring this back to life. If I was a mouse I'd love to live in that cylinder laughing

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10/7/2017 9:07 PM

Mx814 wrote:

Do you have a part # on those poly ball joint covers?

Micahdogg wrote:

$6.99 on the shelf at my local AutoZone.

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Thanks for the info.
smile

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10/11/2017 8:59 PM

Please tell me how you got that white plastic so clean looking (bottom fork cover)!

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10/13/2017 7:25 AM
Edited Date/Time: 10/13/2017 7:26 AM

Bro. Gotta tell me how you got that front brake cover looking so nice. Sandpaper? I restored my 97 yz125 and that’s something I just threw to the side cus it looked like yours before you refinished it. Teach me your ways!! tongue

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10/13/2017 9:52 AM
Edited Date/Time: 10/13/2017 9:53 AM

The key is in the sanding. And the sanding takes time - less time if you learn a good technique. The technique can't be told, you just gotta learn. For instance, don't sand in circles, but you can sand in curves.

I can tell you that first, clean the plastic. Then I work with a flat razor blade to get the rough stuff off. Be careful cause its easy to do more damage, but using a blade lets me jump right into a 320 grit sandpaper. Wet sand with 320, then 400, 600, 800. Then I dry sand 1500, 2000 - finally use a polish. If the sanding is done right, any kinda polish will finish it off well (headlight polish).

The sanding is a bugger and after 800 grit I have to dry sand because I can't see the scratches through the water any longer. Be conscious of your work...you aren't just rubbing sand paper on plastic...you are trying to work out all the scratches.

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10/14/2017 8:08 AM
Edited Date/Time: 10/14/2017 8:14 AM

I love it. My dad bought an 01 yz250f and in about a year I had laid claim to it at 13 years old. Lol had a hell of time getting back on my 80. We did the same and added the auto compression release and put the hot start up in it's place. I rode the piss out of that bike and it never let me down, motor was bulletproof.

Great build, nice in depth coverage. Thanks for sharing.

P.S. can't go wrong with Yamaha of Troy graphics!

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11/9/2017 9:06 PM

I don't know how people can afford to fix stuff on these bikes! smile

Its time to get going on the engine rebuild and the head is definitely the sketchiest part. I'm using a 2005+ head, 2003 cams and cam caps from a completely different head. As you can imagine, the cams did not like a foreign set of cam caps being mounted. Both cams came to a dead stop when torqueing the caps to spec. After massaging the journals to try and relieve some pressure, I figured out where the hangup was and made a "work around" which is in the video.

Now that I have spinning cams, its time to figure out the rest of the head. Its a bare head, seems usable except a valve guide was installed backwards?!?! You gotta be pretty drunk to mess that up I would think, but I have a new valve guide that came with the bike. So I yanked the old guide and I'm gonna heat the head in the oven, freeze the new guide, and then it should drop right in so I've been told.

After that, I have a set of used valves that look good, used springs, but I'm using keepers and washers and stuff from another head. Just tonight I discovered that I am missing two measly keepers for an intake valve. I also found out my new valve seals that came with the bike - they are used. SO I went to ebay and just dropped $18.50 on a two freaking keepers and a set of valve seals. Talk about nickel and diming. Still, based upon the parts I got with the bike I've only had to spend about $85 on this head. With luck, it may even work.

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11/21/2017 8:41 AM

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Just a quick update, I installed all this stuff into the head. A bunch of mix-n-matched parts from other years.

To put it as succinctly as I can, I installed a new valve guide in the middle intake port, I dressed it up with a 5/32 harbor freight drill bit, I lapped an old “sacrificial” valve into that middle valve seat to correct for the angle from my new guide, I ended up judiciously lapping all of my used valves and got them to seal pretty well.

I then assembled all the components and checked for tolerances only to find out that I need several shims in the .90 mm range, and unfortunately 1.20 is about as small as I can find for shims. So I’m going to make my own shims out of some feeler gauges. This head is going to work or else!

Grand total in the cylinder head overhaul is about $108.
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11/25/2017 1:10 PM

Cylinder head done!  Its been an adventure, but the valves are all shimmed, they seal relatively well, feel good in the guides, and my cams are spinning free within the cam caps.  I will place this aside for now and get going on the bottom end.  When it comes time, I'll break this back down and cake assembly lube all over the place, and install my new viton rubber seals for the final assembly.

Grand total was just over $100 into this part.

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11/28/2017 12:30 PM

Now that I can turn the page on the cylinder head for the most part, I moved onto the engine. I split the cases and yanked the crankshaft out.

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Since I'm trying to save money, the plan was to install a new rod onto the old crank. I found a 2001-2002 NOS Wossner rod on ebay for $60 shipped, so I "thought" I would whip it into shape on the cheap. Yeah, then I discovered the shark-teeth timing gear on the stator side crank half. As luck would have it, Yamaha still sold that crank half and I got it for $120 shipped. So now my crank rebuild went up to $180, not quite the huge money saver I was hoping for.

This crank pin was hella tight, but it popped out.

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Here it is pretty much balanced. I would say I'm averaging about .0018 on each end. The manual calls for .0012 with a .002 limit, so I'm probably done. My overall width is a smidge out of spec, the book calls for 55.95-56.00 mm and I'm at about 56.04. Honestly though, I don't know if I can get it tighter and my rod clearance is pretty good (like .30mm).

You can see the old crank web laying on the table. Good thing I got a new one because the "shark-teeth" timing gear was so pointed out that I couldn't get it past the crank bearing. I had to beat it out with a huge hammer, which boogered the threaded end up bad. This bike has had a rough life!

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11/30/2017 6:22 AM

Sweet build will be cool when it is done.

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11/30/2017 9:47 AM

Thanks! I wasn't nuts about the crankshaft so I sat down with it a little more.

I got my overall width at 55.99-56.01mm (spec is 55.95-56.00mm). My big end rod clearance tightened up at .28mm (spec is .15-.45mm), My small end rod freeplay is .035 inch (spec is .02-.04 in) and my runout is .0010 in on the stator side and .0015 on the trans side (spec is .0012-.002 in).

Considering these are two totally different crank webs, I don't know that I should be asking for much better.

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12/12/2017 7:25 AM

Got the cases cleaned up and discovered a couple transmission bearings are junk (in the case at the bottom of the pic). I tried cleaning them up, but they are just too far gone. I can get them for $50 from Yamaha, but considering the amount of metal that I found inside this engine, I'm going to bite the bullet and get a Hot Rods tranny bearing kit for $80.

At least I installed a new crank bearing in that case (in the bottom pic) so I can say that I'm putting it back together at this point smile

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