Any Yz450FX engine failures?

Yamaha YZ450F Engine

33 replies to this topic
  • jrusher

Posted March 07, 2016 - 07:26 PM

#1

Talked with a guy up here today that had 2 of his 450fx bikes go down. Sounds like oil pump failure talked with another guy couple weeks ago same thing had 2  yz450fx bikes go down oil pumps as well. All bikes had oil and filters changed every 4-5 hours they were set up as snow bikes and all around the 50 hour mark on run time. Wandering if anyone else has had or heard of any issues with these new motors?  Im at the 20 hour mark on mine recently did h/c piston and head porting no issues yet



  • stevethe

Posted March 07, 2016 - 08:39 PM

#2

I've never heard of a oil pump failure on a Japanese bike. The Japenese bikes have been using the same type of oil pumps for ions. They don't use plastic gears like the Husaberg, Betas and others. That's where you hear of oil pump failures.

Seems like you might be confused on which bike is which or it has something weird to do with snowbirds or snow bunnies out your way.

  • Monk

Posted March 07, 2016 - 08:55 PM

#3

Sounds wrong. YZ450f all use the same setup and never heard of one of them going out...

  • MidlifeCrisisGuy

Posted March 07, 2016 - 10:27 PM

#4

The engine load on a snowbike is incredibly high.  WOT for long periods of time in ways that you'll never do on a dirt bike.

 

Most mountain riding days are pretty long.  4-5 hours would be every second ride, if not every ride.

 

If I had to guess, I'd say oil failure.  The rads will keep the engine cool, what keeps the oil cool under really high load situations ?

 

Having said that, there are turbocharged YZ450Fs out there.  Not sure how long their engines last.

 

Are we sure that the oil pumps on the FX are the same as on the other and previous 450Fs ?

 

One engine failure is something that could be chance.   Two in the same manner needs looking into. 4 failures to 2 different owners really sounds fishy.

 

Can you get us pictures, more details ?   Call the local Yamaha dealer, they will probably be well aware of the situation.


Edited by MidlifeCrisisGuy, March 07, 2016 - 10:28 PM.


  • jrusher

Posted March 07, 2016 - 11:53 PM

#5

The engine load on a snowbike is incredibly high.  WOT for long periods of time in ways that you'll never do on a dirt bike.

 

Most mountain riding days are pretty long.  4-5 hours would be every second ride, if not every ride.

 

If I had to guess, I'd say oil failure.  The rads will keep the engine cool, what keeps the oil cool under really high load situations ?

 

Having said that, there are turbocharged YZ450Fs out there.  Not sure how long their engines last.

 

Are we sure that the oil pumps on the FX are the same as on the other and previous 450Fs ?

 

One engine failure is something that could be chance.   Two in the same manner needs looking into. 4 failures to 2 different owners really sounds fishy.

 

Can you get us pictures, more details ?   Call the local Yamaha dealer, they will probably be well aware of the situation.

 

I don't have a lot of info yet just that he said he thinks its a oil pump failure  and parts are on back order. Im not familiar with these pumps but from parts fishe its gear driven and it is the same as the 450F model.. I know he mentioned he didn't have thermostats and temp gauges on his bikes which is a must to keep engine temps up and keep it from over fueling. The cold conditions and snow hitting the cases causes  a lot of piston ring blow bye and you get fuel in your oil so that could be a lot of his issues right there.. Im on my 3rd season running my yz450s and now this FX model and its been gas and go but Ive always ran a thermostat and shroud the motor and block rads in as needed..  Even boosted yzs I haven't heard of any issues

 



  • MidlifeCrisisGuy

Posted March 08, 2016 - 08:10 AM

#6

I wonder if cold snow hits the cases and shrinks the oil pump cavity, causing the failure.



  • grayracer513

Posted March 08, 2016 - 09:20 AM

#7

I wonder if cold snow hits the cases and shrinks the oil pump cavity, causing the failure.

 

Clearly not familiar with where the oil pump is located.   It's bolted to the right side crankcase half just behind and below the crankshaft center.  Nothing external directly touches the case.  And it was a fairly silly idea.

 

Remember that the oiling system changed from dry sump to wet sump with the introduction of the '14 Gen4 YZ450F engine, so the pump differs from Gen3 and earlier models in that it's a single pump feeding oil to the lube points while it draws from the sump reservoir.  The pump in the '16 WR and YZFX models, which are also Gen4 engines, is the same as the pump introduced in '14.

 

What we have here is two unsubstantiated claims of failure for which no facts are in evidence for an engine that has no prior history of any endemic weaknesses. 

 

Speculating as to the cause of the problem, even if it actually happened, is about as useful as speculating as to the next Powerball draw numbers, and has roughly the same chance of being correct.

 

The sky is not falling.



  • cowboyona426

Posted March 08, 2016 - 11:25 AM

#8

I've seen the threads on Facebook as well and they caught my attention because I desperately want a 450FX.  The owner of the bikes with failures says he was changing the oil every 5 hours or so as I recall and the filter every other oil change.  But, he also said that the bikes that had failures were rental machines so who knows exactly what they've been put through.  There are quite a few YZ's on the snow with no oil pump failures that I've heard of so I'm not sure why the FX would be any different.



  • jrusher

Posted March 08, 2016 - 12:35 PM

#9

I've seen the threads on Facebook as well and they caught my attention because I desperately want a 450FX.  The owner of the bikes with failures says he was changing the oil every 5 hours or so as I recall and the filter every other oil change.  But, he also said that the bikes that had failures were rental machines so who knows exactly what they've been put through.  There are quite a few YZ's on the snow with no oil pump failures that I've heard of so I'm not sure why the FX would be any different.

Yes the guy I talked to yesterday is using them as rental snow bikes so who knows what they been put through and like i said earlier running these bikes without thermostats is going to lead to over fueling and contaminated oil..Ive seen it in my older yz even with a thermostat on a colder deep deep day I had fuel in my oil.. I run an engine shroud as well and it helps alot with engine temp, no issues with over fueling 

Attached Thumbnails

  • FX shroud.JPG


  • grayracer513

Posted March 08, 2016 - 01:19 PM

#10

Yes the guy I talked to yesterday is using them as rental snow bikes so who knows what they been put through and like i said earlier running these bikes without thermostats is going to lead to over fueling and contaminated oil..Ive seen it in my older yz even with a thermostat on a colder deep deep day I had fuel in my oil.. I run an engine shroud as well and it helps alot with engine temp, no issues with over fueling 

 

This makes the most sense of anything so far. 



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  • MidlifeCrisisGuy

Posted March 08, 2016 - 06:29 PM

#11

I rode dirt/mud/ice/snow trails with a couple snowbikers (on studded dirt bikes) today.  I told them about this situation.  

 

They suspect that there is an issue with the engine breather such that snow is getting into the crankcase and/or the breather is getting plugged.   Apparently they have seen this issue on other bikes and it can wreck engines. 

 

If the engine ingests snow, it melts, makes water, and freezes the oil pump which fails or gets damaged when you start the engine.

 

If the engine had enough gasoline in the oil to cause issues, you'd smell it when you changed oil.  I've run my WR at temperatures well below freezing and never had an issue with fuel in the oil.   It would have to be running really rich to have fuel leaking past the rings into the oil.  That used to happen with carbureted engines before fuel injection is the norm.   Since fuel injection the atomization is excellent and over fueling and fuel in the oil is a thing of the past.

 

I hope we hear what actually happened to these bikes.  I'm hoping to get a YZ450FX someday.


Edited by MidlifeCrisisGuy, March 08, 2016 - 06:34 PM.


  • MidlifeCrisisGuy

Posted March 08, 2016 - 06:39 PM

#12

Clearly not familiar with where the oil pump is located.   It's bolted to the right side crankcase half just behind and below the crankshaft center.  Nothing external directly touches the case.  And it was a fairly silly idea.

 

 

The clearance between the rotating "gears" in the oil pump and the cover is only a few thousands of an inch.  Aluminum contracts like crazy when cold and I bet that when the bike engines were tested (in Japan and California ?), nobody thought to pack one side of the engine in ice while the other side ran super hot due to the high loads a snow bike puts on the engine.   You'd be surprised what kind of stress thermal discontinuities can create.  Especially when the object has a mix of steel and aluminum parts.



  • damnbiker94

Posted March 08, 2016 - 07:04 PM

#13

Oh boy. Here we go. Lol.

  • jrusher

Posted March 08, 2016 - 07:17 PM

#14

I rode dirt/mud/ice/snow trails with a couple snowbikers (on studded dirt bikes) today.  I told them about this situation.  

 

They suspect that there is an issue with the engine breather such that snow is getting into the crankcase and/or the breather is getting plugged.   Apparently they have seen this issue on other bikes and it can wreck engines. 

 

If the engine ingests snow, it melts, makes water, and freezes the oil pump which fails or gets damaged when you start the engine.

 

If the engine had enough gasoline in the oil to cause issues, you'd smell it when you changed oil.  I've run my WR at temperatures well below freezing and never had an issue with fuel in the oil.   It would have to be running really rich to have fuel leaking past the rings into the oil.  That used to happen with carbureted engines before fuel injection is the norm.   Since fuel injection the atomization is excellent and over fueling and fuel in the oil is a thing of the past.

 

I hope we hear what actually happened to these bikes.  I'm hoping to get a YZ450FX someday.

I run a small K&N type filter on my crank case breather line and relocate it up high beside the air box  once again I doubt he was running this as It can cause failures when Iced up or plugged off with snow.  Ive seen fuel in my oil on my older YZ 2010 efi  bike and certain bikes like Hondas 450s efi are notorious for over fueling on a snow bike set up your oil comes out thinned out almost like pure gasoline. Some of the efi bikes ECU sees the the cold air box temps and starts adding more fuel thinking its lean condition a lot of guys run a aftermarket fuel controller and O2 sensor and run real lean mapping..  Warm engine temps and bike set-up shrouding thermostats, blocking in air intakes with pre filter material  etc  are key when plowing through deep powder all day like this pic.. Seen another guy with milky oil few months back same thing not set up properly snow was filling air box up and crank case breather line is attached to air box so snow/water was draining into motor..  I'll try and find out more info on his engine failures but its looking like he didn't have his bikes set-up for the snow.. I was starting to get allittle worried as I just did some motor an head work to mine. Ive never had any issues with any my yammies 250fs, 450fs racing or snow biking and same with boosted sleds always been reliable :)

Attached Thumbnails

  • snow bike yz.jpg

Edited by jrusher, March 08, 2016 - 07:30 PM.


  • grayracer513

Posted March 08, 2016 - 07:18 PM

#15

  You'd be surprised what kind of stress thermal discontinuities can create.  Especially when the object has a mix of steel and aluminum parts.

 

 

No, I'm actually quite familiar with the effect, and a number of other details relating to thermal conductivity in dissimilar metallic assemblies.  You could pack the right side cover of the engine in dry ice if you wanted and it wouldn't have a significant effect on the oil pump at all during operation, although it probably would keep the oil somewhat colder.  You will find, in such a condition, a distinct temperature difference right at the joint of the cover to the case, for one thing, simply due to the insulating effect of the gasket.

 

Any temperature changes packing the right side in snow could possibly cause at the oil pump will be buffered further against sudden changes by the fact that the partition on which the pump is mounted is separated by an air space and makes contact with a heat conductor with a path to the ice pack only at the edges.

 

Regarding fuel contamination in cold weather, it's well documented in the '10 and later EFI models.  Search for complaints of oil smelling of gas and rich operation in cold weather and you'll find lots of it.  The EFI simply isn't set up to handle that kind of weather on a bike with no thermostat, and it stays nearly cold-start rich all the time.  Nothing stunning or even new about that.

 

The ice in the breather idea sounds at least plausible.  In order to work, though, the water in the oil would need to freeze, then the engine be restarted after it had cooled long enough to allow that.  Maybe if the renters keep  the bikes for multiple days, or take long breaks.  Any water in the oil should be quickly emulsified into the "pale chocolate shake" looking foamy sludge a lot of us have seen before, depending on how long it ran after ingesting it.  Having that crud frozen stiff in the oil lines would be unfortunate at the least.

 

Hopefully, we'll find out more.  From the people you talked to, it sounds like it's not a Yamaha problem. 



  • drtrcr400

Posted March 08, 2016 - 07:43 PM

#16

I rode dirt/mud/ice/snow trails with a couple snowbikers (on studded dirt bikes) today. I told them about this situation.

They suspect that there is an issue with the engine breather such that snow is getting into the crankcase and/or the breather is getting plugged. Apparently they have seen this issue on other bikes and it can wreck engines.

If the engine ingests snow, it melts, makes water, and freezes the oil pump which fails or gets damaged when you start the engine.

If the engine had enough gasoline in the oil to cause issues, you'd smell it when you changed oil. I've run my WR at temperatures well below freezing and never had an issue with fuel in the oil. It would have to be running really rich to have fuel leaking past the rings into the oil. That used to happen with carbureted engines before fuel injection is the norm. Since fuel injection the atomization is excellent and over fueling and fuel in the oil is a thing of the past.

I hope we hear what actually happened to these bikes. I'm hoping to get a YZ450FX someday.


For the record the YZ450FX model has the crank breather hose routed into the intake boot, not down to the bottom frame rail like the regular YZ450F. As Grey stated above the fuel dilution issue is a more likely cause of the alleged problems.

  • Summit

Posted March 08, 2016 - 08:21 PM

#17

Hmm maybe they weren't intended to be snowmobiles?

  • MidlifeCrisisGuy

Posted March 08, 2016 - 09:20 PM

#18

So what does the spark plug look like on a engine that is over fueling so much that it dilutes the oil ?  How can it even run if there is fuel on the cylinder walls, running past the rings ?

 

I'm quite familiar with over fueling Yamaha FI bikes because it turns out that WRs have what appears to be a glitch in the FI programming.   If you start the bike when it is cold out, well below freezing, and you blip the throttle before the engine reaches operating temperature, it will die.   No big deal, except that when you attempt to restart it, it floods like crazy and almost no amount of regular kicking or cranking will get it to clear.  Even after sitting for days, the bike will still flood like crazy when kicked.   The solution in this case is to tow the bike and hold the throttle wide open until it clears and fires.   I've observed it to be a repeatable problem on several bikes.

 

While we are talking about issues with Yamaha FI systems, the manifold pressure sensor reads wrong on WRs.  It consistently reads less pressure than what is present.  I suspect this is part of the hard starting/lean issues on WRs.   The reason I mention this is because given these FI issues, it wouldn't surprise me if Yamaha didn't do a great job of mixture calibration at sub freezing temperatures and high elevations.

 

As far as snow ingestion goes, air boxes are among the worst places to put a crankcase breather to prevent snow ingestion.   I've run several trucks, a few snowmobiles (!) and the odd tractor that would suck snow into the air box and pack it right full in the right conditions.  Remember that Yamaha probably didn't expressly design these bikes to run in snow.

 

I disagree with your thermal induced stress analysis, but I don't care to argue the details.

 

I hope we learn what caused these engine failures.

 

Edit: the easiest way to resolve this issue is to grab an oil sample and send it in for analysis.  This is routinely done for large heavy equipment.  


Edited by MidlifeCrisisGuy, March 08, 2016 - 09:35 PM.


  • jrusher

Posted March 08, 2016 - 10:41 PM

#19

So what does the spark plug look like on a engine that is over fueling so much that it dilutes the oil ?  How can it even run if there is fuel on the cylinder walls, running past the rings ?

 

The one time I had fuel in my oil the bike ran like always never missed a beat never noticed any rich conditions or power loss..Was crazy deep weekend and -15 degrees Celsius. Oil was like thinned right out with gas was crazy.. Never pulled the plug.. Thing always started 1 or 2 kicks

 

I'm quite familiar with over fueling Yamaha FI bikes because it turns out that WRs have what appears to be a glitch in the FI programming.   If you start the bike when it is cold out, well below freezing, and you blip the throttle before the engine reaches operating temperature, it will die.   No big deal, except that when you attempt to restart it, it floods like crazy and almost no amount of regular kicking or cranking will get it to clear.  Even after sitting for days, the bike will still flood like crazy when kicked.   The solution in this case is to tow the bike and hold the throttle wide open until it clears and fires.   I've observed it to be a repeatable problem on several bikes.

 

While we are talking about issues with Yamaha FI systems, the manifold pressure sensor reads wrong on WRs.  It consistently reads less pressure than what is present.  I suspect this is part of the hard starting/lean issues on WRs.   The reason I mention this is because given these FI issues, it wouldn't surprise me if Yamaha didn't do a great job of mixture calibration at sub freezing temperatures and high elevations.

 

As far as snow ingestion goes, air boxes are among the worst places to put a crankcase breather to prevent snow ingestion.   I've run several trucks, a few snowmobiles (!) and the odd tractor that would suck snow into the air box and pack it right full in the right conditions.  Remember that Yamaha probably didn't expressly design these bikes to run in snow.

 

I disagree with your thermal induced stress analysis, but I don't care to argue the details.

 

I hope we learn what caused these engine failures.

 

Edit: the easiest way to resolve this issue is to grab an oil sample and send it in for analysis.  This is routinely done for large heavy equipment.  

 



  • RockerYZWR

Posted March 09, 2016 - 05:13 AM

#20

Oil analysis won't resolve the alleged issue.





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