On long wheelies will the yz450 starve for oil?


11 replies to this topic
  • adaguy

Posted November 23, 2004 - 01:21 PM

#1

I read on another thread someone said that your rod journals will gaul if you ride really long wheelies, is this true?

  • motocrosschump

Posted November 23, 2004 - 02:07 PM

#2

Nope.

  • cgaluter

Posted November 23, 2004 - 02:34 PM

#3

The whole idea about the dry sump oil system is to avoid oil starvation regardless what orientation the engine is at. If the oil level is where it should be , the motor will always get adequate lubrication.

  • grayracer513

Posted November 23, 2004 - 02:43 PM

#4

This is the kind of thing that is more likely on a wet sump engine that either has a very small oil supply, like a CRF (and I don't know that it would happen to one of them), or one that shares oil with the transmission. (Ducati spent quite a bit of time on the latest 996 to correct this)

What has to happen is for the bike to stay in an attitude where the oil runs back too far in the crankcases for it to be picked up by the pump, and run that way long and/or hard enough for the engine to suffer from it.

In the case of the YZF, even with the wheels oriented vertically, most of the oil in the tank could still run down to the feed line to supply the oil pump, and at realistic angles that occur during wheelies, it all could. So then, not only would you need to meet the conditions above, you would also have to run the engine like this long enough to empty the oil tank into the crankcase without returning any to the tank.

Furthermore, while it might seem like there would be a lot of space for oil to hide in the back of the case, with the transmission there, and all, there really isn't. Because of how Yamaha laid out the cases and positioned the scavenging oil pump screen, it appears to me that no more than half the engine oil would need to be present in the sump to cover the scavenging screen if tilted back at 50-60 degrees. This would mean that oil would again start returning to the tank while half of it was still there, feeding the pump.

Remember that Yamaha knew they were building a dirtbike when they started this project, and they've heard of things like hillclimbs and 2 mile wheelies. :cry:

  • John_Lorenz

Posted November 23, 2004 - 02:49 PM

#5

I read on another thread someone said that your rod journals will gaul if you ride really long wheelies, is this true?


:cry: :cry: :cry: :cry:

Dont let anyone kid you

Long wheelies cause all sorts of stuff, from starving the engine with taburculosis to causing your main thurster bearing to catch a STD and thats bad.

Never Never Enever Wheelie more the 15 foot and never loop it that is even worse :cry: Glad I can help

  • motobark

Posted November 23, 2004 - 05:29 PM

#6

I read on another thread someone said that your rod journals will gaul if you ride really long wheelies, is this true?



If it was I would have gone through a dozen rods by now!

I love to wheelie and I can tell you it doesn't seem to hurt YZ450's. Or YZ426's, YZ250f's, YZ250's, YZ125's, YZ85's, XR400's, XR250's, XR100's, XR80's, and just about every other bike I've owned back to when I used to wheelie my QA50!
H#ll, I even figured out how to wheelie our International Cub Cadet garden tractor when I was a kid! I did have a little trouble trying to get the front end up on my friend's Harley Softail though. That would have been pretty ugly if I blew the motor on a Harley while on the back wheel!

Wheelie all you want, contrary to what John Lorenz says, nothing bad will ever happen to you while riding a dirt bike on only one wheel!

John

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • YZ250F_Rider

Posted November 23, 2004 - 05:35 PM

#7

I think John may be riding the trampier bikes. Imagine getting an STD from doing a wheelie on a dirtbike. :cry:

  • grayracer513

Posted November 23, 2004 - 05:40 PM

#8

I think John may be riding the trampier bikes. Imagine getting an STD from doing a wheelie on a dirtbike. :cry:

That's why I never ride a bike I don't know without a latex seat cover. :cry:

  • FFRacing79

Posted November 23, 2004 - 06:22 PM

#9

That's why I never ride a bike I don't know without a latex seat cover. :cry:

LOLOLOLOL ROTFLMAOGTYF!

  • jespertheil

Posted November 25, 2004 - 08:45 AM

#10

My friend screwed his rod on his ´04 CRF450 because of wheelies.

  • grayracer513

Posted November 25, 2004 - 09:54 AM

#11

My friend screwed his rod on his ´04 CRF450 because of wheelies.


This is the kind of thing that is more likely on a wet sump engine that either has a very small oil supply, like a CRF (and I don't know that it would happen to one of them), or one that shares oil with the transmission. (Ducati spent quite a bit of time on the latest 996 to correct this)

I wondered about that. 700cc of oil in a wet sump is a little light, IMHO.

  • BC3

Posted November 25, 2004 - 11:34 AM

#12

Because of the superior coating ability of MOST current four stroke oils I find it
very hard to believe that when the oil pressurer goes away from a WHEELIE
that the rod or main bearings will fail.... Oil shoot-outs have proven that even
under great loads (wheelies not one of them) bearings survive even after
severak minutes.......So unless your wheelie is 15 miles long (doubtful) The
rod bearing shouldn't be affected........Unless your using FREDDY FAST GAS OIL
and even then I don't think there would be a failure....I have been riding long wheelies for 35 years....both with dry sump and wet sump bikes and never
blew up because of it..... :cry:

BC :cry: Didn't blow up........





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