2021 yz 450 engine failure ?

Boomslang 5/22/2021 1:38am
5/22/2021 1:38am
DirtRoadmx47 wrote:
Friends 30 hour 2021 yz 450 engine suffered catastrophic engine failure on first lap ? well maintained stock bike ? anybody have this happen to their...
Friends 30 hour 2021 yz 450 engine suffered catastrophic engine failure on first lap ? well maintained stock bike ? anybody have this happen to their 21 yz 450 ?
You want the answer to the cause of the blowup? Have a experienced mechanic open the motor up and he will be able diagnose the cause.

With the position of the airfilter extra caution needs to be taken when swopping out airfilters on the Yamaha. A crumb of dirt falling down the intake can be the catalyst to a future failure.

Good luck going forward..... and use that Stimulus check for the repairs.Whistling
PNWRider
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PNWRider 5/22/2021 8:10am
5/22/2021 8:10am
Camp332 wrote:
Best answer I got is, he probably doesn't even lift Bro.
Probably skipped leg day. Never skip leg day.
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PNWRider
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PNWRider 5/22/2021 8:17am
5/22/2021 8:17am
zookrider62! wrote:
30 hours is one hell of a long lap time
Way back when, my dad and I were loading our bikes from the hotel room to the truck on race morning. It was 5am at a “questionable” hotel (anyone who raced Jolly Rogers near SeaTac should know the Motel 6 off I-5...) and some guys who never went to bed were wandering the parking lot, beer in hand. One asked if we’d raced at Washougal. Went on to tell us his experience with a friend’s bike in which it took him almost an hour to do one lap...

Of course, we also got to hear all about his “buddy who raced the pro circuit for Honda”...which over the years I’ve learned means somewhere between free stickers and a 10% parts discount...
1
Blade Flanagan jr. 5/23/2021 10:08am
5/23/2021 10:08am
Do Yz's come from the factory with an hour meter or was it added? The bike may have way more hours than that.

The Shop

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Stewable
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Stewable 5/23/2021 10:16am
5/23/2021 10:16am
Blade Flanagan jr. wrote:
Do Yz's come from the factory with an hour meter or was it added? The bike may have way more hours than that.
hours can be seen after connecting to the gytr app via the wifi emitter
sgrimmxdad 5/24/2021 4:46am
5/24/2021 4:46am
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
2
Boomslang 5/24/2021 4:54am
5/24/2021 4:54am
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
Exactly what you say. Most common way to destory a Yamaha engine.

UpTiTe 5/24/2021 5:08am
5/24/2021 5:08am
Brent wrote:
[i]"WAIT- engine oil needs to be [u]changed?[/u]"[/I] ...said my ex wife when her Suburban blew up after 60K miles on the original oil.... :laugh: :laugh: :laugh...
"WAIT- engine oil needs to be changed?"

...said my ex wife when her Suburban blew up after 60K miles on the original oil....


Laughing Laughing Laughing Laughing Laughing Tongue
If she was your wife at the time, sorry, but that’s on you
6
JBecker 72
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JBecker 72 5/24/2021 5:11am
5/24/2021 5:11am
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure nothing fell in.
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mx317
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mx317 5/24/2021 5:36am
5/24/2021 5:36am
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
JBecker 72 wrote:
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure...
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure nothing fell in.
I have the Twin Air kit on my 450 that helps with keeping clean air going in. I really do doubt that poor air filter maintenance would lead to the top of the rod snapping off though.
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Skerby 5/24/2021 7:08am
5/24/2021 7:08am
Idk if we can safely blame this on filter maintenance. It's not totally impossible for a rod to let go at 30 hours, I saw this happen before on an 09 yz250f.
1
mattyhamz2 5/24/2021 7:22am
5/24/2021 7:22am
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
JBecker 72 wrote:
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure...
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure nothing fell in.
A few mechanics have told me they lay the bike over when replacing air filters on the 14+ Yamaha's.
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Skerby
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Skerby 5/24/2021 7:32am
5/24/2021 7:32am
mattyhamz2 wrote:
A few mechanics have told me they lay the bike over when replacing air filters on the 14+ Yamaha's.
I use the twin air wash cover and spray out the airbox every time I wash, seems to help. This filter is really not as bad as some people make it out to be. If you remove the radiator shrouds it makes it pretty foolproof.
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predel323
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predel323 5/24/2021 7:55am
5/24/2021 7:55am
I use a shop vac with a narrow tip on it to clean out around the bottom of the filter where all the crap accumulates BEFORE I pull the filter off- in 6 years of riding YZ250FX‘s I’ve never had an issue
5
mattyhamz2 5/24/2021 8:03am
5/24/2021 8:03am
mattyhamz2 wrote:
A few mechanics have told me they lay the bike over when replacing air filters on the 14+ Yamaha's.
Skerby wrote:
I use the twin air wash cover and spray out the airbox every time I wash, seems to help. This filter is really not as bad...
I use the twin air wash cover and spray out the airbox every time I wash, seems to help. This filter is really not as bad as some people make it out to be. If you remove the radiator shrouds it makes it pretty foolproof.
I just recently worked on a friends 21 and didn't think it was all that bad either. I had a 14 and had no issues with that either.
TheGetFresh 5/24/2021 8:51am
5/24/2021 8:51am
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120. If you don’t have Milwaukee batteries, pretty much ever brand that makes power tools/batteries has a cordless vac. It’s a useful tool for these bikes.
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DaBaum44
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DaBaum44 5/24/2021 4:32pm
5/24/2021 4:32pm Edited Date/Time 5/24/2021 4:34pm
TheGetFresh wrote:
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120...
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120. If you don’t have Milwaukee batteries, pretty much ever brand that makes power tools/batteries has a cordless vac. It’s a useful tool for these bikes.
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags just cleaning out the bottom portion of the airbox.

Now a KTM owner and I can change the air filter in a quarter of the time with way less worry about any debris entering the air boot.

To the OP, I've seen several times on Instagram (from legit engine builders) where some of the new YZ450F's are having rod issues. I'm not an engine expert by any means but I follow the industry close and it almost resembles the 2014 YZ250F motors that were frequently blowing OEM rods.
1
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KAWI642 5/25/2021 6:40am
5/25/2021 6:40am
TheGetFresh wrote:
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120...
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120. If you don’t have Milwaukee batteries, pretty much ever brand that makes power tools/batteries has a cordless vac. It’s a useful tool for these bikes.
DaBaum44 wrote:
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags...
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags just cleaning out the bottom portion of the airbox.

Now a KTM owner and I can change the air filter in a quarter of the time with way less worry about any debris entering the air boot.

To the OP, I've seen several times on Instagram (from legit engine builders) where some of the new YZ450F's are having rod issues. I'm not an engine expert by any means but I follow the industry close and it almost resembles the 2014 YZ250F motors that were frequently blowing OEM rods.
I sent one of my 2020 YZ 450'S to get a top end done at 50 hours. Mechanic called and said " you going to have to put a crank in this bike" the hole the pin goes thru at the top of the crank was "egg shaped" or oblonged. I do not think dirt would have caused that.

Because parts were backed up in February i bought another new 2020 so we would have a bike to ride. The "Yamaha's are bulletproof" argument does not hold up in my experience and the Air filter system is the worst design to ever be put on a MX bike. I know of several catastrophic failures that have occurred on these bikes with less than 30 hours.
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Pit Row

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tzmike
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tzmike 5/25/2021 8:02am
5/25/2021 8:02am

From 20hr 450f.
Crack extended down both sides of top of wrist pin boss
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outerlimits 5/25/2021 5:07pm
5/25/2021 5:07pm
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
JBecker 72 wrote:
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure...
Yup. I am super careful when I change filters on my 21 YZ250F. I always shine a flashlight down in the air box and make sure nothing fell in.
mattyhamz2 wrote:
A few mechanics have told me they lay the bike over when replacing air filters on the 14+ Yamaha's.
That's a good idea!
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Up Wind 5/25/2021 5:49pm
5/25/2021 5:49pm
SilverSpurs wrote:
Dumgeon time.

Probably run with no oil or the filter in backwards.
yz133rider wrote:
They aren’t all perfect from the factory. Things happen.
He probably forgot to put oil back in after he changed it.
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skeef 5/25/2021 5:52pm
5/25/2021 5:52pm
"I don't like yamaha, so here is my petty post about my "friends" bike"
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PNWRider 5/25/2021 8:16pm
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tzmike wrote:
[img]https://p.vitalmx.com/photos/forums/2021/05/25/494803/s1200_20210520_105329.jpg[/img] From 20hr 450f. Crack extended down both sides of top of wrist pin boss

From 20hr 450f.
Crack extended down both sides of top of wrist pin boss
I believe Kawi was having that issue on their 450’s awhile back, leading to them spec-ing a stronger piston. 2008-2010ish if memory serves.
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BeachMX 5/25/2021 8:35pm
5/25/2021 8:35pm
sgrimmxdad wrote:
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some...
I'd lean towards poor filter maintenance, we have a 20 in the shop that is completely trashed. Having to do complete bottom end and top. Some how the customer got MUD into the engine through the air boot....

We are careful as can be when doing filters on our 20, we still had to take it down recently and clean the air boot. I don't know how to be more careful when removing a dirty filter, I think it is nearly impossible to take out a seriously dirty filter without something dropping on that cage. I am considering the Twin Air kit just to make it easier to clean the air boot out.

Filter placement is one thing I wish Yamaha could take lessons from KTM on.... I miss the KTM filter changes for sure lol!
I use a vacuum cleaner to clean out my box every time time.. stick the tube right in there. I actually vacuum the top of the air filter BEFORE taking it off I'm so paranoid of dirt getting in there

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LungButter 5/25/2021 8:38pm
5/25/2021 8:38pm
PNWRider wrote:
I believe Kawi was having that issue on their 450’s awhile back, leading to them spec-ing a stronger piston. 2008-2010ish if memory serves.
I had an ‘06 Kawi that cracked 2 just like that, both pistons under 50 hours.
SilverSpurs
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SilverSpurs 5/26/2021 12:11am
5/26/2021 12:11am
TheGetFresh wrote:
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120...
I have one of these that stays in the van and use it for the air filters. If you have the batteries, the vacuum is $120. If you don’t have Milwaukee batteries, pretty much ever brand that makes power tools/batteries has a cordless vac. It’s a useful tool for these bikes.
DaBaum44 wrote:
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags...
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags just cleaning out the bottom portion of the airbox.

Now a KTM owner and I can change the air filter in a quarter of the time with way less worry about any debris entering the air boot.

To the OP, I've seen several times on Instagram (from legit engine builders) where some of the new YZ450F's are having rod issues. I'm not an engine expert by any means but I follow the industry close and it almost resembles the 2014 YZ250F motors that were frequently blowing OEM rods.
KAWI642 wrote:
I sent one of my 2020 YZ 450'S to get a top end done at 50 hours. Mechanic called and said " you going to have...
I sent one of my 2020 YZ 450'S to get a top end done at 50 hours. Mechanic called and said " you going to have to put a crank in this bike" the hole the pin goes thru at the top of the crank was "egg shaped" or oblonged. I do not think dirt would have caused that.

Because parts were backed up in February i bought another new 2020 so we would have a bike to ride. The "Yamaha's are bulletproof" argument does not hold up in my experience and the Air filter system is the worst design to ever be put on a MX bike. I know of several catastrophic failures that have occurred on these bikes with less than 30 hours.
Photo of worn small end and details of how out of spec it was please.

A dealer mechanics word could be taken with a grain of salt.

1
KAWI642
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KAWI642 5/26/2021 4:57am
5/26/2021 4:57am
DaBaum44 wrote:
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags...
I had a 2017 YZ250F and looking back I wish I had purchased one of these. I would spent a legit 10 minutes with shop rags just cleaning out the bottom portion of the airbox.

Now a KTM owner and I can change the air filter in a quarter of the time with way less worry about any debris entering the air boot.

To the OP, I've seen several times on Instagram (from legit engine builders) where some of the new YZ450F's are having rod issues. I'm not an engine expert by any means but I follow the industry close and it almost resembles the 2014 YZ250F motors that were frequently blowing OEM rods.
KAWI642 wrote:
I sent one of my 2020 YZ 450'S to get a top end done at 50 hours. Mechanic called and said " you going to have...
I sent one of my 2020 YZ 450'S to get a top end done at 50 hours. Mechanic called and said " you going to have to put a crank in this bike" the hole the pin goes thru at the top of the crank was "egg shaped" or oblonged. I do not think dirt would have caused that.

Because parts were backed up in February i bought another new 2020 so we would have a bike to ride. The "Yamaha's are bulletproof" argument does not hold up in my experience and the Air filter system is the worst design to ever be put on a MX bike. I know of several catastrophic failures that have occurred on these bikes with less than 30 hours.
SilverSpurs wrote:
Photo of worn small end and details of how out of spec it was please. A dealer mechanics word could be taken with a grain of...
Photo of worn small end and details of how out of spec it was please.

A dealer mechanics word could be taken with a grain of salt.

i don't have that but i did see it with my own eyes and attempted to put pin in with my own hand.
mx317
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mx317 5/26/2021 6:13am
5/26/2021 6:13am
PNWRider wrote:
I believe Kawi was having that issue on their 450’s awhile back, leading to them spec-ing a stronger piston. 2008-2010ish if memory serves.
My friend's 2013 KX450F cracked like that. It had about 70 hours on it though.
tingo
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tingo 5/26/2021 6:24am
5/26/2021 6:24am
SilverSpurs wrote:
Dumgeon time.

Probably run with no oil or the filter in backwards.
Even worse, the engine was in backwards.
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