2006 yz450f piston blow out

Looking for some advice here! New to the site and pretty new to dirt bikes. A couple of months ago I got a great deal on my 06 yz450f. Please correct me if I say anything wrong I'm learning.

The previous owner told me he had the top end rebuilt and it had about 12 hours on it. He didn't know much more about the history of the bike.

Last weekend I let my brother take it for a test ride up the street. He said he was doing about 80 when the bike stalled and the engine seized. I tried rolling it backwards in gear thinking it was just the decompression valve but after removing the spark plug and it was still seized up I figured something was very wrong.

I removed the engine, took off the head and cylinder to find the connecting rod tore right off the piston and destroyed the cylinder. There's pieces of piston all over the engine. The crank still spins

I'm wondering now what's my next step

IMG_1474602685.580175.jpgIMG_1474602704.152258.jpg IMG_1474602715.852524.jpgIMG_1474602738.433134.jpg

That motor is toast.

Crank will be bent, and everything above it is ruined.


I would part the bike out, unless it is special/you are attached to it.


Make your brother pay for it!

If you can do the work yourself you will be into it at least $1500-$1800 (maybe more). So, it really comes down to how much you like that particular bike.

Buy a new motor. That piston seized and tore the pin right out of the bottom. Either got hot or didn't have the proper clearance when installed.

I don't think it was a good idea to let your brother borrow your bike.

Dude didn't gap the rings

We'll before I throw away the crank and assume the engine is toast why don't I actually test it? The most runout I'm getting is .002" and the manual says the limit is .0012". Anyone actually have experience with this? IMG_1475382665.277654.jpgIMG_1475382680.915019.jpgIMG_1475382692.870134.jpg IMG_1475382703.548735.jpg IMG_1475382719.432229.jpg

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