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2001 YZ250N restoration

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I am currently in the process of rebuilding my YZ250 2-smoker and after seeing yammerhaas304 thread, I found some motivation to start my own. I did not want to highjack his with all the details of my build and figured it would be easier to differentiate the 2 down the road.

Let's start with a little history. I purchased my Y-Zinger brand new in the summer of 2001 and it was the last one available in northern Cali. I had to wait a week for them to ship it from another dealer. Once it arrived I was able to view it still in the crate and then had to wait another day for them to complete the assembly. This was my very first new bike so you can imagine how tough it was to wait through the process. On the first ride, I could not believe how well everything worked and how much power it had for a 250. If you have never had a new bike before, save, steal, or Scrooge your way to one. It's one of the greatest feelings in the world.

Over the next 10 years the bike has given me flawless reliability. I couldn't have been happier with the blue beast. I traveled all over California to many OHV locations until a failed 150ft road jump attempt at Carnegie OHV ended my fun on 2 wheels for a year and I had throw it in mothballs until I recovered from surgery.

There it sat, taunting me and a reminder that my days of my high flying glory was over. This prompted the purchase of a new WR450, which as most of you know, is more of a trail riding Cadillac. Shortly after the decision to sell the motocrosser came to mind. "I'll never ride that thing again!"

A couple years go by, my fondness for the WR grew and still not having the heart to sell old blue, it sat, pushed aside and almost forgotten behind 2 other bikes. Peering over the Harley and WR, I could almost hear it whimpering in pain like an abused Irish setter and looking at me with eyes that said "Why?!"

After some deliberation with my inner demons I found that it was time to resurrect the beast and bring it back to its former glory. It will be a long road but I feel I owe the machine some attention after all the epic rides and never leaving me on the side of the trail. Even after letting it go riderless in the the weeds and bailing out over a double then watching it tumble end over end to rest in a ditch.

Ok, so here we go! Let's start with pics of the bible and the condition it was in before the teardown.

Here she is, looking good, but underneath... a mine field of neglect and worn out parts.

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It's seen a lot of use over the years but the information that pours from its pages will be priceless.

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Next post will be a list of what's bad, what's good, and what I'll be doing to bring it back to the light. If you haven't had a stroke from boredom and you've read this far then I thank you! Stay tuned!

-Skip-

2009 WR450

2001 YZ250N (restoration in progress)

1998 FXR Sportster (aka the Fixster)

Check out some of my adventures on YouTube here...

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After disassembly I found serval items that required replacing.

ImageUploadedByThumper Talk1408310913.586258.jpg

All the swing arm bearings were dry and completely wasted. Front and rear wheel bearings shot. Air filter fell apart after cleaning.

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But worst of all, after taking the too end off, I found a crack across 2 of the exhaust ports. Not good :-/

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-Skip-

2009 WR450

2001 YZ250N (restoration in progress)

1998 FXR Sportster (aka the Fixster)

Check out some of my adventures on YouTube here...

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Frame after paint. I used a frame paint resto kit from colorrite. Comes with just enough paint to complete the project. I would almost recommend buying an extra can if you want it a little thicker.

ImageUploadedByThumper Talk1408422209.869414.jpg

After inspecting for cracks and some serious prep here's the finished product.

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ImageUploadedByThumper Talk1408422356.018812.jpg

-Skip-

2009 WR450

2001 YZ250N (restoration in progress)

1998 FXR Sportster (aka the Fixster)

Check out some of my adventures on YouTube here...

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I started getting a little excited once the frame was dried so I missed some step by step pics for the bearing replacement in the swing arm, rear shock, headset, front and rear wheels. Needless to say they were wasted. The lower link was almost seized bit luckily it didn't spin the bearings and take out the link.

This shows most of the frame reassembled. Front forks were rebuilt just prior to the teardown and fitted with Race Tech Gold Valves. I only was able to ride on them for about 2 miles, then due to my aforementioned injury I had to head back but they felt amazing!

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ImageUploadedByThumper Talk1408423106.263017.jpg

-Skip-

2009 WR450

2001 YZ250N (restoration in progress)

1998 FXR Sportster (aka the Fixster)

Check out some of my adventures on YouTube here...

Edited by skip510

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Checked the crank and connecting rod for wear and miraculously after 10 years of hard riding, it's still within spec. A true testament to Yamaha engineering.

Since the bottom end is good I decided to place it back in the frame. It's much easier to put the top end back on that way.

ImageUploadedByThumper Talk1408510786.985529.jpg

ImageUploadedByThumper Talk1408510815.248205.jpg

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I'm highly skeptical of the "ten years of hard riding crank."

Not to be a downer, just hate to see your project ruined in the near future.

But it's either not been ridden hard or should be replaced. A junker your spending no time and money on I guess you could say a pray. A ground up restoration, I'm not so sure. Freshen it and you're guaranteed another ten years.

I can only assume you've measured the thrust washer gap. Which isn't the best measure of wear. Plus you can't really measure crank bearing wear.

Were there any other ways you measured the assembly?

And after ten years you'd notice a huge reduction in vibration with a freshening off the bottom end.

Edited by Supertuner_tb
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I'm highly skeptical of the "ten years of hard riding crank."

Not to be a downer, just hate to see your project ruined in the near future.

But it's either not been ridden hard or should be replaced. A junker your spending no time and money on I guess you could say a pray. A ground up restoration, I'm not so sure. Freshen it and you're guaranteed another ten years.

I can only assume you've measured the thrust washer gap. Which isn't the best measure of wear. Plus you can't really measure crank bearing wear.

Were there any other ways you measured the assembly?

And after ten years you'd notice a huge reduction in vibration with a freshening off the bottom end.

Your correct on both counts. So your saying that there is no real way to ensure the bottom end is good without splitting the cases when you follow the guidelines within the factory manual?

Not criticizing your commented there is validity to it, I just want to understand why you believe the measurements while the crank is on the case would not be sufficient. I truly want to know if you think the risk is too great.

Edited by skip510

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Your correct on both counts. So your saying that there is no real way to ensure the bottom end is good without splitting the cases when you follow the guidelines within the factory manual?

Not criticizing your commented there is validity to it, I just want to understand why you believe the measurements while the crank is on the case would not be sufficient. I truly want to know if you think the risk is too great.

Honestly no. The weakest link is the lower rod bearing. Unless you split the crank and can take a very accurate measurement of the lower rod bore it's a guess. You could measure small end bore really enough. But at minimum requires snap gauges and a micrometer, Not a vernier. Best is a bore gauge. Also if you measure rod end pay, back and forth. That's not terribly easy.

Also there are other things to consider. For example parts lifing. In my job we closely monitor usage on critical components. After they've reach a certain amount of time/miles whatever they are taken out of service even if they show no cracks under magnafluxing and maintain their dimensions.

Also crank bearings can be an issue. I would bet money on an engine with kinda time. If you spun that bearing by hand then a new one you notice a huge difference.

Replacing those parts is were you get that smooth vibration free like knew feel.vibration is the killer. It will advance wear quickly.

But thinking about it from a parts lifing aspect is the best way. That's how to maintain it while reducing there risk of failure before it happens.

Edited by Supertuner_tb

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I had another thought... Let's start a debate on this. Looking at the price for a new or rebuilt crank is not something to take lightly for me since I already had to buy a complete new top end including cylinder since the original was cracked and pretty much a guarantied fail. That being said, I want to be sure the bottom end is good so not to take out all the new hard parts but I also don't want to break the bank. I've been struggling with how far to take the build since I have a new bike that I ride regularly and this is more of a "fun" project and not out of necessity. The ol YZinger probably will not be ridden much going forward and either sit pretty in the garage or possibly go to a new owner in the near future.

Let's take a poll and get some thought on this. We already know not going through the lower end in its entirety is a risk. I do know what the bike has been though and the maintenance I've done since I'm the original owner. I can tell you I've always run 32:1 Redline gas/premix ratio and never "raced" the bike and riding style was more woods than track. So I didn't have the motor bouncing off the rev limiter consistently. The top end was gone through regularly and pistons and rings changed at their normal intervals per the factory guide (not sure if that would make a difference on the lower end). Something else to consider, the new top end could add extra stress the the high hour lower as well.

So what's everyone think? Can I safely use the bottom end and go by the recommended runouts in the manual or will too many unknowns (such as bearings) be too large a risk?

Edited by skip510

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Well... Last night I assembled the top end. After this mornings deliberation with Supertuner_tb it may be striped down again. However while that decision is being made we can still enjoy what it looks like now. :-)

ImageUploadedByThumper Talk1408556469.459089.jpg

ImageUploadedByThumper Talk1408556514.708997.jpg

ImageUploadedByThumper Talk1408556562.126168.jpg

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You should leak test the motor before you put it back in the frame

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You should leak test the motor before you put it back in the frame

With a new top end I would think a leak test wouldn't be very accurate until after break in, piston conforms to the new cylinder and the rings seat. But I defer to the professionals on that. Compression is very evident as it sits now.

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With a new top end I would think a leak test wouldn't be very accurate until after break in, piston conforms to the new cylinder and the rings seat. But I defer to the professionals on that. Compression is very evident as it sits now.

 

Leak test not compression test =]

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Well... Last night I assembled the top end. After this mornings deliberation with Supertuner_tb it may be striped down again. However while that decision is being made we can still enjoy what it looks like now. :-)

ImageUploadedByThumperTalk1408556469.459089.jpg

ImageUploadedByThumperTalk1408556514.708997.jpg

ImageUploadedByThumper Talk1408556562.126168.jpg

I'm really not trying to be a downer. If you're capable of doing this work which seems apparent. It's cheap insurance.

Currently I'm restoring a 2000 yz125. The top end is blown but the bottom end is still one piece. I'm not trusting that bottom end. One two fives are more wear prone. But once done I'll have no worries about riding it hard and far from camp.

You do have the benefit of knowing your bikes history. Which honestly the good care you've taken is probably why it's lasted so good. And why it may not require a new rod. But to be honest, why not at that point?

I was thinking about what might place it into perspective. Imagine you're buying this bike and the current owner says the bottom end had 10 hard years riding on it.

Although it's had good oil and clean filters, how would that make you feel? I imagine you'd not trust that bottom end.

Also while the bike hasn't been raced. I find trail machines as worn or more than race bikes. A guy going to the track is running max an hour where as a good day on the trail can be 4 to 6 or more hours. And a race bike is often getting oil changes and clean filters every time out. Trail machines are often ridden hard and put away wet and taken out again next weekend.

Once apart you can measure the rod. If it's truly still in spec then thrust washers and a lower rod bearing plus crank bearings/seals will be all it needs. I'd do water pump bearing and seals at the same time. Cheap and easy.

Then you'll have a bike that a.) You can pretty much keep forever ride hard and never worry or b.) Legitimately demand top dollar for if selling it.

Edited by Supertuner_tb

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Thanks! I hope so. You got me really thinking about the lower end now though. Hmm....

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Few more items completed. Added an hours meter so I can follow maintenance schedules more accurately and it was a gift! Free is always good!

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