09 yz450 seized after running great new to 4 strokes

Hey guys I just picked up an 09YZ4 50 in a trade it ran great everything sounded great when I met the kid wrote it for about five hours total and now it's seized we were at a sandpit riding for about three hours it started stalling in neutral while idling I didn't think anything of it then it tried to stall while running in gear I just gave it more throttle it felt as if it was running wth 100 percent power then died I let it sit for like 20 minutes when to kick it the kicker moved about half way very hard now it's completely locked up I'm not a mechanic but I'm not a retard either I could diagnose it wth a little help I've been finding it could b a timing thing carb thing or it's just blown up so suggestions to diagnose please this is my first 4 stroke but I've had bikes forever

Hey man I had a similar problem not to long ago. I was riding it up a ramp on my toy hauler and it slipped and landed hard on its side well running. After that I could kick maybe one kick then then next kick was impossible. I could literally stand on the kicker and it wouldn't move. Kind of felt like it built a shit tonb of pressure up.. found out it was the timing chain.. super easy fix .. YouTube yz450 timing or tdc and it took me maybe 15 minutes.. all you need is a socket set a flywheel puller which is like 10 bucks on amazon. If you want to check the timing easily all you have to do is pull the 2 large hex bolt screws on the left side cover and take the top cover off and spin the nut in the bottom whole until the marks line up.. if they don't line up follow the instructions on the video and it's cake man. Just did this for the first time 3 days ago

But that's kind of a temporary fix for you.. you didn't bang it really hard so it sounds like something else might have caused it.. worth a try checking you timing. It's easy

If it comes down to being the timing I'll definitely use Tht Info here's an update it's been about 5 hours since this happened to me and the bike will kick over now compression feels normal did. It start it tho didn't even try

So it wont start? What about like 4 or 5 kicks? Does it lock up sooner or later?

Oil?

Water?

Air cleaner?

Sorry didn't see the typo I didn't try to start it I just randomly went to kick it bc I was a little upset and it kicks over just like it should I don't wanna start it and hurt it more and krannie water level is good oil was a little low almost to bottom of dipstick don't kno how Tht happened and the air filter is definitely ready for replacement doing oil change and filter when this is figured out

Cam timing (replace the chain and tensioner, and look for signs of cams seizing to the head)

Bent valve against the piston (usually starts as a cam timing problem)

Connecting rod big end bearing

Well I took it to shop an apparently the air filter wasn't on properly one shop says by the amount of sand in air box whole engine needs rebuild top to bottom other shop says they can pull it apart save wht looks good and replace whts bad I think I'm gonna pull it apart my self I kno I can do top end I may have to send bottom out for camshaft and bearings

Well I took it to shop an apparently the air filter wasn't on properly one shop says by the amount of sand in air box whole engine needs rebuild top to bottom other shop says they can pull it apart save wht looks good and replace whts bad I think I'm gonna pull it apart my self I kno I can do top end I may have to send bottom out for camshaft and bearings

Dang I'm sorry to hear about this. Not sure if I would just cut your losses and sell the bike. I just sold a mint condition 09 for $2600. I picked up a 2013 the other day for $3000, 53 hours. Gonna be at least $1000 plus for the rebuild.

The rod bearing on crankshaft seized up im replacing crankshaft assembly bearings rod and piston 550 for parts labor shouldn't b too bad I took it all apart and brought bottom of engine to shop to have crankshaft done

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