When to replace Wr450f piston and rings?!

Yamaha WR450F Engine Pistons

63 replies to this topic
  • Adamridesorange

Posted March 06, 2014 - 05:40 PM

#1

Hello, I'm looking at buying a 2008 wr450f from a friend of mine but first I have a question about it.
I'm wondering about the maintenance on these bikes. I know the newer generation four strokes aren't reliable like the old xrs. I ride trails in which some are open, and I do a lot of messing around such as racing friends and hill climbs, ect. In which I rev the bike out, but keep up on maintenance at the same time. On average how many hours do you guys get out of a piston and rings on these bikes?
Any advice, suggestions, ect is appreciated! Thanks.

  • Krannie McKranface

Posted March 06, 2014 - 05:51 PM

#2

Lot's of variables make it so there is no definitive answer.

 

If all other things are equal, you should be looking at the piston after 100-150 hours of hard riding.

Measuring the piston and cylinder to see if they are withing service limits is the proper way.

 

I get about 200 and then you can hear it start to slap/rock.

 

There are guys who say they get 300+ hours. 

 

You should not be comparing any part of a 2003 or later four stroke with any older four stroke built before that, because they are not 'slipper piston' motors, and everything is different, from oil quantities to piston type, to pretty much everything.

Old four strokes spin slow, and have tons of reciprocating mass and poor top end.

New ones spin very fast, and can be made to perform at any rpm.

 

You should spend some time here reading in this forum, and reading the FAQ section.



  • William1

Posted March 06, 2014 - 06:00 PM

#3

To add, you are comparing a Porsche RSR (the WR)to a Chevy Cobalt (the XR). Both have an engine, four tires, are driven on the street and can carry a passenger and luggage.

 

Wear and tear on a race bike/high performance sports car will always be greater than on a daily commuter. To what level of service is needed is dependent on how you take care of it and how demanding you are on its' abilities.

 

If you do not need the capability of a race bike and do not want the servicing needs of a thoroughbred, then maybe a WR is not the right bike. If you want a Yamaha, then perhaps a TTR is more in line. Only you can fairly make that determination.



  • Adamridesorange

Posted March 06, 2014 - 06:08 PM

#4

Well the whole idea is that I own a ktm 250exc (2 stroke) right now and I have replaced the piston at around 200+ hours and find minimal wear at tear down. and it goes the same way with the ktm 2 strokes, there's some people out there with over 300 hours (I know I know I'm in the yamaha section bragging about ktms!) but I'm just trying to figure out if the wr will be worth it or if it's going to be more maintenance? Once again thanks a lot guys!

  • Krannie McKranface

Posted March 06, 2014 - 07:24 PM

#5

If you are getting 200 hours on a KTM 250 two stoke piston, you are babying that motor to a high degree.

 

... 75 hours absolute max is more like it.....a green-bar GNCC racer (intermediate) needs a piston every 5th race. That's about 25 hours....

 

Two stoke pistons wear at least twice as fast as a four stroke, and usually faster.

Two strokes don't go catastrophic and fail like a four stroke. That does not mean they wear longer, just that they blowup less.

 

" I find minimal wear" ....are you mic-ing the parts with a micrometer ??  What you mean is " I find minimal damage upon tear-down.."  which is not the same thing.

 

You can't 'see' most of the wear......and there is no way to know if you are in service limits without measuring.

 

I'll bet your bore is way out.....

 

A four stroke absolutely positively needs more attention and maintenance than a two stroke....if it is neglected.

But you get 10 times the control (gyroscopic effect) and 10 times the traction, and nearly a 40% wider power band.

 

The Yamaha WR motors are the most reliable high performance motors on the planet.


Edited by TheKoolAidMadeMeSick, March 06, 2014 - 07:29 PM.


  • cubera

Posted March 06, 2014 - 08:17 PM

#6

Good discussion. Many variables. My personal experience with KTM 2-stroke is 40 hours max on a piston. That's a 2010 300XC-W. Must have been a lemon. 2011 530XC-W 100 hours max on rings. After that it guzzles oil and with the dinky amount it holds on that side makes it easy to run dry. My 2004 YZ 250 ran 180 hours on a new piston and at tear down was still in spec. 2007 CRF450R 80 hours and seized but it was heavily abused an overheated forcing it to do abnormal things it was not designed for. 2005 450X variable but generally would not want to push it beyond 150 hrs. without taking a look. Damn thing would virtually run forever with an Agent Smith head making it really easy to put too many hours on a piston....seriously. What's the book say about the WR450? FWIW riding I do (not enough lately) ranges from tight one track to my preferred higher speed open desert/ Baja type riding. I'm an old slow guy.


Edited by cubera, March 06, 2014 - 08:22 PM.


  • Adamridesorange

Posted March 07, 2014 - 03:52 AM

#7

Alright so maybe a four stroke isn't the best idea since they are such high maintenance.
And on my bike I do ride it easy sometimes in the trails, but also ride it fairly hard when the trails open up. I just keep up on maintenance and run good oil. At tear down there is no sign of any catastrophic failure about to occur, last tear down was at about 190 over this winter and the rings were still in spec and that was after riding it hard on the ice for about a month and a half. I was reading a forum of some one that pushed a ktm 300exc as far as 600 hours! Now that is insane!

  • Krannie McKranface

Posted March 07, 2014 - 06:47 AM

#8

 2007 CRF450R 80 hours and seized but it was heavily abused an overheated forcing it to do abnormal things it was not designed for.  APPLAUD, APPLAUD! :applause:

2005 450X variable but generally would not want to push it beyond 150 hrs. without taking a look. Damn thing would virtually run forever with an Agent Smith head making it really easy to put too many hours on a piston....seriously.

MY EXPERIENCE AS WELL. 200+ HOURS NO PROBLEM

What's the book say about the WR450? FWIW riding I do (not enough lately) ranges from tight one track to my preferred higher speed open desert/ Baja type riding. I'm an old slow guy.



  • grayracer513

Posted March 07, 2014 - 07:56 AM

#9

One of the most accurate ways to gauge ring condition is a leak down test.  Properly conducted, such a test will identify the source and severity of any loss of cylinder sealing, and you can go from there.

 

In truth, the real issue with WR's and other modern high performance four-strokes is the piston, rather than the rings.  The rings are a stabilizing influence on the piston, but the real concern is whether the piston runs straight in the bore.  When I did the first piston in my '06 last summer (yes, that is 8 years.  300 hours, too) I found that I had left the thing go just a wee bit longer than I should have.  The piston was beginning to contact the bore at the ring lands ( the area between the rings), which is never supposed to happen, but there was no damage as a result.  Also part of the piston concern is wear in the ring grooves that allows the rings to twist around their circumference at TDC/BDC.  That causes the rings to dig out "shadows" of higher wear at the top and bottom of the swept area.

 

On tear-down, ring gap is another good indicator.  Rings are pretty cheap, though, and replacing them a little more often can extend the life of the piston and the bore.



  • stevethe

Posted March 07, 2014 - 08:24 AM

#10

Geez I know someone that still rides the piss out of a WR400. Never does anything other than oil changes and air filter cleanings.

 

I suppose if it blew up it might do him a favor and he could up grade. But no such luck !



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  • 3MTA3

Posted March 07, 2014 - 02:20 PM

#11

Geez I know someone that still rides the piss out of a WR400. Never does anything other than oil changes and air filter cleanings.

 

I suppose if it blew up it might do him a favor and he could up grade. But no such luck !

I have 90 hours on a WR since a rebuild.  I have 2 more months until it will be a year since the rebuild so just taking a ball park average I will say 110 hrs/yr.  It was 5 years before this rebuild which happened to be the first and only time the head was removed from the bike.  Lucky I guess.  I hope it does the same for the next 5 years :thumbsup:



  • Adamridesorange

Posted March 07, 2014 - 07:56 PM

#12

It seems like the older wr400/426 and maybe even the early 450s are more reliable then the newer wr 450s. What did they change or do that made them like this, are the newer ones pushing out more performance than the older ones, causing them to not last quite as long?

  • stevethe

Posted March 07, 2014 - 10:49 PM

#13

It seems like the older wr400/426 and maybe even the early 450s are more reliable then the newer wr 450s. What did they change or do that made them like this, are the newer ones pushing out more performance than the older ones, causing them to not last quite as long?

 

 

I don't think the new ones are any less reliable than the old. There were a few years that had some faulty valves that broke at the stem, however they were fixed. I believe the 03' WR had a issue with the flywheel key, that was also a factory fixed issue.



  • Adamridesorange

Posted March 08, 2014 - 06:49 AM

#14

Alright, it just seems like people say they go forever on wr400 top ends and never have to tear them apart after years and years of hard riding, where as the 450s have to be torn down at around 200 hours?.. Maybe I'm wrong.

  • miweber929

Posted March 08, 2014 - 07:02 AM

#15

Alright, it just seems like people say they go forever on wr400 top ends and never have to tear them apart after years and years of hard riding, where as the 450s have to be torn down at around 200 hours?.. Maybe I'm wrong.

Sorry to say but yeah, you're wrong. Will they run with a worn out piston? Sure, and that's what you're thinking of. Will it fail at the most inopportune time? Probably, and it'll take much more expensive things with it.

In the world of high performance singles, 200 hours is forever maint time wise.

Mine

  • Adamridesorange

Posted March 08, 2014 - 07:09 AM

#16

Alright I see. So you think 200 hours should be a safe interval to change parts out on a 450 if your riding a mix or trails and faster terrain?
Thanks.

  • beezer

Posted March 08, 2014 - 07:53 AM

#17

I think if you keep fresh oil in it and a clean air filter the bike will run forever.

 

The bikes on the east coast last longer because there isn't much dust in the air like in Southern California.



  • Adamridesorange

Posted March 08, 2014 - 07:55 AM

#18

I didn't think these bikes would last "forever" because they aren't like the old XRs that do last forever..

  • 3MTA3

Posted March 08, 2014 - 09:15 AM

#19

Now the conversation is getting into the right/wrong (East) :D coast realm. I can't really say what is harder on a bike, wet, muddy slower stuff of the wrong coast or the higher speed dusty, rocky stuff of the right coast. Depending on the right or wrong half of the right coast (So Cal being right for edification purposes).

All kidding aside, when it comes to the dust aspect, a well maintained air filter shouldn't allow much past it. The inner boot past my filter is spotless. Filter cleaned after every ride then oiled with Maxxima FFT. Then the requisite prostate exam, can't let the gloves go to waist and I can't see paying the Dr. for it. A two birds with 1 finger kinda thing. Obamacare, what a f'n joke :lol:

  • Adamridesorange

Posted March 08, 2014 - 12:01 PM

#20

So are u saying riding in the east coast, I should still be looking at doing a top end around 200 hours? I mean a lot of the trails here in maine are fairly open and fast going terrain, so it's not like the bike is being ridden that slow on tight single track..





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