YZ250F Motors are Bulletproof

Leeham
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Leeham
Lost my oil drain bolt last weekend while warming up for the day out on the track. Came back to the truck and oil was dripping off my skid plate. Only God knows how long I was running with low/no oil. Wasnt especially noisy when I parked it. Only noticed when I saw my bike dripping. And I am not shy with the limiter. Took a look at the clutch and cams. Perfect condition. Either I just lost it that last lap, or Maxima oil did its job. Astounding

Dont know how I lost it though. I KNOW I torqued the bolt because I am paranoid of exactly what happened. Bad freaking luck I guess, but the exact same thing happened to my brother the very next day with the same bike. And he says he got it tight. Only thing in common is the brand BOLT copper crush washers.
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AH387
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AH387 6/18/2021 11:06am
6/18/2021 11:06am
Shit that is still scary though. I'm about to go look at mine lol.
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yak651
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yak651 6/18/2021 11:29am
6/18/2021 11:29am
Always a nightmare to think about, so I just don't look at mine until it's time to change the oil!
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Moto520
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Moto520 6/18/2021 11:29am
6/18/2021 11:29am
I did 2 hours in sand without engine oil in my 2013 honda CRF250R. i rode it hard for those 2 hours because.....well......sand. It blew up at 2 hours but i still thought that was pretty good.
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Leeham
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Leeham 6/18/2021 11:40am
6/18/2021 11:40am
At first I thought I caught a rock straight through my holes in mh skid plate to my case and wrecked it. Hahaha oh well. I didnt do anything major, maybe took a couple hours off its life for 5-10 minutes lol

The Shop

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Murph
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Murph 6/18/2021 11:53am
6/18/2021 11:53am
It might be a nuisance, but lockwiring bolts like this one is sometimes worth the effort.
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yzf162
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yzf162 6/18/2021 12:27pm
6/18/2021 12:27pm
Leeham wrote:
Lost my oil drain bolt last weekend while warming up for the day out on the track. Came back to the truck and oil was dripping...
Lost my oil drain bolt last weekend while warming up for the day out on the track. Came back to the truck and oil was dripping off my skid plate. Only God knows how long I was running with low/no oil. Wasnt especially noisy when I parked it. Only noticed when I saw my bike dripping. And I am not shy with the limiter. Took a look at the clutch and cams. Perfect condition. Either I just lost it that last lap, or Maxima oil did its job. Astounding

Dont know how I lost it though. I KNOW I torqued the bolt because I am paranoid of exactly what happened. Bad freaking luck I guess, but the exact same thing happened to my brother the very next day with the same bike. And he says he got it tight. Only thing in common is the brand BOLT copper crush washers.
Same thing happened to me in January 2018 yz250f. Changed the oil rode for 2 full days. Parked the bike. Week later we went to monster Mountain. Oil bolt backed out somehow and the bike shut down just as i got out of the rollers had it been any sooner that would have hurt. Never had that happen before. An im anal about my drain plugs.
Timo
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Timo 6/18/2021 12:48pm
6/18/2021 12:48pm Edited Date/Time 6/18/2021 2:43pm
Leeham wrote:
Lost my oil drain bolt last weekend while warming up for the day out on the track. Came back to the truck and oil was dripping...
Lost my oil drain bolt last weekend while warming up for the day out on the track. Came back to the truck and oil was dripping off my skid plate. Only God knows how long I was running with low/no oil. Wasnt especially noisy when I parked it. Only noticed when I saw my bike dripping. And I am not shy with the limiter. Took a look at the clutch and cams. Perfect condition. Either I just lost it that last lap, or Maxima oil did its job. Astounding

Dont know how I lost it though. I KNOW I torqued the bolt because I am paranoid of exactly what happened. Bad freaking luck I guess, but the exact same thing happened to my brother the very next day with the same bike. And he says he got it tight. Only thing in common is the brand BOLT copper crush washers.
Only way it backed out was it wasn't torqued, or it was over torqued and the threads came with it.
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Leeham
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Leeham 6/18/2021 1:14pm
6/18/2021 1:14pm
Timo wrote:
Only way it backed out was it wasn't torqued, or it was over torqued and the threads came with it.
I mean I guess thats what happened. But I have no idea, I guess every moto ill be checking that now lol
sgrimmxdad
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sgrimmxdad 6/18/2021 1:32pm
6/18/2021 1:32pm
Ive done it before too, I guess didn't tighten enough on a 16 YZ250f. Luckily the bike stalled in a corner, looked down and saw the last little bit of oil draining out. Filled it back up with a new filter installed and the bike never missed a beat!
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Leeham
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Leeham 6/18/2021 2:39pm
6/18/2021 2:39pm
Ill just be happy I caught it and ride like it didnt happen. Bike is good. If I roached the cams on the 21, I would SOL for a long time. Unavailable currently it seems
walent215
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walent215 6/18/2021 2:42pm
6/18/2021 2:42pm
Same with our 16 yz250f
Unreal that I have heard it from so many people with this model bike
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Rickyisms
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Rickyisms 6/18/2021 5:17pm
6/18/2021 5:17pm
My KTM 125 made it through a whole harescramble without the drain plug in too, it started making a strange “whirring” noise about an hour and a half in but I managed to limp it all the way home. I use Maxima as well and everything looked fine upon tear down, slight heat marks on certain parts but there was still a very strong oil film on all the parts that needed it. I rebuilt it anyway, but other than that noise the bike didn’t skip a beat.

I drilled my new drain plug and use a safety pin tie wired to another bolt now to avoid that ever happening again, I was so pissed at myself!
Nairb#70
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Nairb#70 6/18/2021 6:36pm
6/18/2021 6:36pm
Don't celebrate too soon, you probably flattened a roller brg. on the big end of the rod and it will get noisy in a couple of rides.
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smoothies862
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smoothies862 6/18/2021 6:44pm
6/18/2021 6:44pm
I found it therapeutic to safety wire. I would do all the usual suspects
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BikePilot
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BikePilot 6/18/2021 6:59pm
6/18/2021 6:59pm
Buell recommends a sealant on their drain bolt. It’s not as stiff as even blue lock tight but is enough that a drain bolt is not likely to come out. Perhaps run that for safety?
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Johnny Lock 6/18/2021 7:48pm
6/18/2021 7:48pm Edited Date/Time 6/18/2021 7:51pm
I remember back in the n-style/LBZ days (99-00) a review from a racer that ran a Supercross heat sans oil in his 2 stroke gearbox. He always used Maxima and for whatever reason failed to fill it after draining. The clutch and gears lasted the moto. Was for their MTL fluid as I recall.

I bet more than one Vitard has run out to their garage to check their oil drain bolt today after reading the OPs post.
vitalriderCrf 6/18/2021 7:59pm
6/18/2021 7:59pm
This happened to a buddy of mine’s 2015. He was checking that oil pressure bolt on the side of the head (forget what it’s called specifically) and forgot to put it back. Lost a ton of oil out on the track. That was almost two years ago and he’s still riding it. I love how easy the shock is to get to on that bike! Yamaha makes good stuff.
TheGetFresh
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TheGetFresh 6/18/2021 10:36pm
6/18/2021 10:36pm
How are you guys drilling your safety wire? Straight thru or angled? I really want to safety wire the drain and filter cover bolts but don’t have a press for it. Any tips appreciated.

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Stewable
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Stewable 6/18/2021 10:51pm
6/18/2021 10:51pm
Your torque wrench may not be accurate. I'd just use a normal wrench make it tight by feel.
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Brad460
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Brad460 6/19/2021 6:10am
6/19/2021 6:10am
Stewable wrote:
Your torque wrench may not be accurate. I'd just use a normal wrench make it tight by feel.
Agreed- Normal wrench for most people..

But I think you have a group of people who shouldn’t be working on their own bikes and still wouldn’t get it right. They will either strip it or leave it loose.

Same as the bolt coming loose when using a torque wrench. You would think using a torque wrench is fail proof, but this thread proves otherwise. Folks don’t know how to use those either.

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PNWRider
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PNWRider 6/19/2021 6:30am
6/19/2021 6:30am
OE crush washers.

The OP referred to a “Bolt” washer-I presume he meant Bolt brand-an aftermarket bolt kit vendor.

The only issues I’ve ever had with crush washers not sealing (and poor gaskets) is by using off-brand stuff.

Those bolt kits are great for when you lose a number plate bolt at the track, but I wouldn’t trust them on anything critical.

I had two different dripping coolant drain bolts that I couldn’t figure out until I swapped OE washers back on.
LKHill
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LKHill 6/19/2021 6:39am
6/19/2021 6:39am
There is a reason they use aluminum crush washers. If it was still dripping it was not OUT of oil. Your oil pump may have been starved. Check you filter for copper. Also trans damage may not be evident and manifest itself in future rides. GL.
Moto520
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Moto520 6/19/2021 8:38am
6/19/2021 8:38am
Copper ring every other oil change. There’s enough oil in the cavities of the bikes motor to keep it lubed up for a bit.
PNWRider
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PNWRider 6/19/2021 9:03am
6/19/2021 9:03am
Given what can happen If an engine shits the bed on a jump, I’d be doing a full teardown...but that’s just me.
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BeachMX
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BeachMX 6/19/2021 6:15pm
6/19/2021 6:15pm
I just did this... Must have not tightened it enough

Bike lost compression and died. looked down to see oil coming out the bottom. bought a new cylinder and piston, but still making a noise when up to operating temp, along with backfiring. Starts perfect, timing is perfect, sounds great when cold.

I'm at a loss for what it is. Any ideas? It's like a ticking sound.

bh84
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bh84 6/19/2021 6:50pm
6/19/2021 6:50pm Edited Date/Time 6/19/2021 6:51pm
I had a rock punch a hole in my engine case on my 09 KTM 450 and drain the oil

Unfortunately the only thing we could salvage from the motor was the transmission. Piston skirt snapped off, piston turned sideways and that was the end of my poor pumpkin
Nairb#70
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Nairb#70 6/19/2021 8:24pm
6/19/2021 8:24pm
BeachMX wrote:
I just did this... Must have not tightened it enough Bike lost compression and died. looked down to see oil coming out the bottom. bought a...
I just did this... Must have not tightened it enough

Bike lost compression and died. looked down to see oil coming out the bottom. bought a new cylinder and piston, but still making a noise when up to operating temp, along with backfiring. Starts perfect, timing is perfect, sounds great when cold.

I'm at a loss for what it is. Any ideas? It's like a ticking sound.

See my above post. The ticking sound is probably a flattened roller brg. in the big end of rod. First thing to go when oil pressure is low.
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rjg
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rjg 6/19/2021 8:31pm
6/19/2021 8:31pm Edited Date/Time 6/19/2021 9:09pm
Here the thing, if that drain plug is coming loose that means there is vibes shaking loose for whatever reason and materials are effected. Probably well within expected and tolerances. Those engines are bulletproof these days glad you spotted it. I remember a husky going +10mins without coolant as well.
Zoom
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Zoom 6/19/2021 8:50pm
6/19/2021 8:50pm Edited Date/Time 6/20/2021 6:12am
The best motor in the class but definitely not bulletproof. Seen a few YZ250F (2019-2021) motors blow up including ours because of cam chain failures with very low hours. We have starting changing the cam chain at 15 hours.

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