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What did you do to your Yamaha YZ 2 stroke today?

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Posted (edited)
56 minutes ago, LSHD said:

My fault, or maybe just a coincidence. I swapped back to summer jetting on Monday (42/170/NEDJ-2/#8 Slide/0.046" squish). Had the bike on the stand with an industrial fan blowing on it. Got it up to temp to set idle and I noticed it started to buck a little bit each time I gave it some throttle. Braaap, braaap, braaap, bzzzzzzzzzzzmmmmmpppp - locked up tight. I've done the stand thing forever and never had issues. A three foot industrial fan puts out huge amounts of airflow. Needle was at 1 turn out during warm up and the bike sounded fantastic before the disaster. So thinking maybe it was a coincidence. Rather it happen on the stand than way down at the bottom of a Parson's Mountain trail (which I rode last week).

Pretty sure the lower end gave way, throwing brass and steel up past the ports and causing the piston to break and seize. Shipping it to YZDOC today and installing my original 2005 that he rebuilt and converted into a YZ250X transmission for me a couple years ago. It's been sitting in the crate, ready to go. While he was rebuilding it, I bought a new crate 2017 engine, and that is the one that blew. Only had about 50 hours on it. Can't wait to try that transmission in the 2005.

If you ever need someone you can trust to rebuild a YZ engine, or an entire YZ (and many other brands), you can trust YZDOC to do it correctly and at a fair price. Gary is a good man. He is also shockingly fast compared to many shops. Can't find the words to recommend him highly enough.

Been doing this long enough to see things just happen.  Looks like big end bearing took a shit id say is what started it anyway.  The 19' in post i just did the ring broke and hit port ruined cylinder.  Bike had 5hrs on it. Sometimes it just happens no matter what . Keep a spare top end around for them and others if need in pinch. Comes in handy its got a few threw the weekend . Have bearings and cranks too lol . 

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Edited by Motox367
Found pic of it

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1 hour ago, Motox367 said:

Been doing this long enough to see things just happen.  Looks like big end bearing took a shit id say is what started it anyway.  The 19' in post i just did the ring broke and hit port ruined cylinder.  Bike had 5hrs on it. Sometimes it just happens no matter what . Keep a spare top end around for them and others if need in pinch. Comes in handy its got a few threw the weekend . Have bearings and cranks too lol . 

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I think you are right. Things happen. I keep a spare engine on hand so I can ride while YZDOC makes the broken engine like new again. 🙂

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2 minutes ago, LSHD said:

I think you are right. Things happen. I keep a spare engine on hand so I can ride while YZDOC makes the broken engine like new again. 🙂

Yes he will 🔧🔧🏁

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2 hours ago, LSHD said:

Agreed. That is my standard summer jetting and is used by many of us here that have had squish done and NEXJ-series needles. 42 might be slightly lean, but if so, just barely.

Any chance that fuel didn't have oil in it? Everything looks very dry, at least in the pictures. Sorry man that stinks, at least you have a spare...DOC is a good man

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1 hour ago, Kinger317 said:

Any chance that fuel didn't have oil in it? Everything looks very dry, at least in the pictures. Sorry man that stinks, at least you have a spare...DOC is a good man

There is definitely a chance, but a very small chance. I have a pre-mix storage tank with PREMIX written HUGE on the side. Fuel never goes into the tank before oil. Dump in oil, then add fuel and mix. I fueled the bike with that fuel. Plenty of blue-gray smoke while I warmed up the bike, so pretty sure only premix is in there. Plus, the tank was half full already. I don't think it would seize with 60:1 premix either just warming up on the stand with that huge fan blowing on it.

Edited by LSHD
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4 hours ago, Kinger317 said:

Any chance that fuel didn't have oil in it? Everything looks very dry, at least in the pictures. Sorry man that stinks, at least you have a spare...DOC is a good man

DOC is a good man. So glad he rebuilt my 2005 engine for me. Next to having a duplicate bike, it's the best I can do right now.

Edited by LSHD
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Posted (edited)

New custom GFX from SKDA.  Great company and high quality easy to install.

IMG_20200501_105421.jpg

Edited by El Diablo Rojo
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Nice ride with my 14 year old son on his 2001 YZ 144. 

 

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It was such a nice day out today so I took my project outside. Got a little help from my kid 😎👍 The dude loves bikes... and garbage trucks for some reason... but mostly bikes! 20200502_165433.thumb.jpg.000affea602523fcf44d30e1261a6cd2.jpg

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Cleaned everything up since I shipped the motor to YZDoc. Started getting the motor YZDoc rebuilt for me that I had on the shelf ready to install by bolting on the common parts from my blown motor (Ricky Stator, squished head, reeds, etc.). 

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20 hours ago, Tahoe Gator said:

Rode some baby bear singletrack: Not too dry, not too wet—just right

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What kind of speed does it take to get across that pond?!!

  • Haha 3

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On 5/3/2020 at 4:28 PM, Tahoe Gator said:

Rode some baby bear singletrack: Not too dry, not too wet—just right

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Where is that trail located, looks nice

 

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8 hours ago, Kinger317 said:

What kind of speed does it take to get across that pond?!!

Same question! :thinking:

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11 hours ago, foxtrot722 said:

Where is that trail located, looks nice

 

Near Macon, Georgia. It was, especially if you like tight and twisty. I must say it was nice to ride a trail that was mostly hard pack dirt with hardly any water. There’s been so much rain this spring that some places are still a mess of standing water. 

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11 hours ago, Piney Woods said:

Same question! :thinking:

You know, like this...

Ha. I was surprised to see that too! Must be a map error or remnant.

 

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Put some ufo plastic on the 03....kept the older style shrouds though....

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Different plastic,fuel tank,graphics,47881861-B1C5-455D-B01D-1DAB6A01BB3C.jpeg.a1d6577d1bd745a2dcce6ed8874d970a.jpegpipe on the 16 .....just for a laugh....

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