How Often You Guy Changing Pistons?


35 replies to this topic
  • cracker please

Posted September 03, 2014 - 07:03 AM

#21

I am sure I have to pull the whole motor out to change the rings and/or piston.

I think most people leave the bottom end in the frame.



  • Just_a_trail_rider

Posted September 03, 2014 - 07:08 AM

#22

Ok, I will buy a leak down tester to find out where I sit with the piston. What are the tolerences?

 

I am sure I have to pull the whole motor out to change the rings and/or piston. Where is a good place to purchase Rings and a piston cheap? What other tools do I need like piston rings sleeve collar or what?

 

Winter is coming, might as well for security measure do this if it is that important.

15-20% leakage is when they say you need to be making some repairs.   

 

For a 426, you can do the piston change without removing the entire engine.   If you do decide to remove the engine, be sure to break the head bolts loose before you do.    But... you will have plenty of room to work and I wouldn't remove it.   Working on the engine while on the bench is different.  Just be patient getting the rings onto the piston and the piston back in the cylinder.      Oh... make sure you know how to put that timing chain back where it belongs.


Edited by mauricedorris, September 03, 2014 - 07:09 AM.


  • underground-mpyre

Posted September 03, 2014 - 07:18 AM

#23

With it being in the frame, the trick to put it on it's side I would assume?



  • avlisj

Posted September 03, 2014 - 07:24 AM

#24

You got 80 hrs out of a KTM piston? I could only get 60hrs on my xcf before oil flow issues started chewing up my cam journals and the cams and everything else. Three expensive rebuilds in three years with very little riding :banghead: . (wait... this is not the KTM thread...) Back on topic...

When I had my 05 wr, I easily got over 500 hrs with no valve adjustments The bike just kept running and running. IMO, 80 hrs is way too soon to be worrying about a wr450.


Can you elaborate more about the head issues on your ktm. My buddy's got a 08 klx 450. Very few hours on after a professional valve job and found his cams and journals discolored and worn when he went to check spec,while there still was oil pooled under the valve cover. Now there telling him he needs a new head due to the journal wear. Did you find the cause of your problem?

  • Just_a_trail_rider

Posted September 03, 2014 - 07:45 AM

#25

Can you elaborate more about the head issues on your ktm. My buddy's got a 08 klx 450. Very few hours on after a professional valve job and found his cams and journals discolored and worn when he went to check spec,while there still was oil pooled under the valve cover. Now there telling him he needs a new head due to the journal wear. Did you find the cause of your problem?

Now you bringing up bad memories...    I know nothing about the klx450, but on my ktm, which was the 08 xcf, there were known issues with the oil pumps not adequately lubricating the top end.   Having oil there isn't good enough.    It needs to flow at the proper pressure to the right places. If the coating is worn off of the cams, then it will chew up the journals along with the cam.     For me it was a combination of an oil flow issue coupled with the coating on the cam being insufficient.   My bike was professionally maintained as well.

 

I got totally and completely pissed off at this recurring problem and parted out the bike.    

 

I blame myself though.  I ordered the wrong part from the wrong dealer.  I should have ordered a "wr450f" from the guys up the street.  



  • cubera

Posted September 03, 2014 - 07:46 AM

#26

You got 80 hrs out of a KTM piston?   I could only get 60hrs on my xcf before oil flow issues started chewing up my cam journals and the cams and everything else.    Three expensive rebuilds in three years with very little riding  :banghead: .   (wait...   this is not the KTM thread...)   Back on topic...  
 
When I had my 05 wr, I easily got over 500 hrs with no valve adjustments   The bike just kept running and running.     IMO, 80 hrs is way too soon to be worrying about a wr450.


I get 80 hrs. on the 530 and after that it uses too much oil on a ride to ride with any confidence. It also loses power around those same number of hours. Now this is true of the 530 which is my second KTM. On the other hand, no valve issues on the KTM after a couple hundred hrs. but the gearbox roached at around 130 hrs. My first KTM was the legendary 300, a 2010 XC-W, which I could not keep a piston longer than 40 hrs. without significant issues. This was arguably the biggest POS ever made.

Now CRF's are a different story. They'll run virtually forever once the heads are done right but after 80 hrs. on piston I've had trouble like cracked and broken pistons more than once and at least two occasions where that caused a snapped rod or smoked main bearings or both. So no more than 80 hrs. on a CRF 450 piston is a good general guideline which has served me well through several of these motors.

My last Yamaha was a 2003 YZ250. After I rebuilt it completely, it was virtually indestructible. Now I have the 2013 WR and I like it a bunch but for damn sure the piston will not be going any 200 hours. That won't work with the conditions I ride in or the type of riding and racing I do. So I'm hoping to get it torn down on schedule and the head sent off to AS Racing where Paul can port and immortalize the head:) When I get it back there will be new piston to go with it.

  • avlisj

Posted September 03, 2014 - 08:03 AM

#27

Now you bringing up bad memories... I know nothing about the klx450, but on my ktm, which was the 08 xcf, there were known issues with the oil pumps not adequately lubricating the top end. Having oil there isn't good enough. It needs to flow at the proper pressure to the right places. If the coating is worn off of the cams, then it will chew up the journals along with the cam. For me it was a combination of an oil flow issue coupled with the coating on the cam being insufficient. My bike was professionally maintained as well.

I got totally and completely pissed off at this recurring problem and parted out the bike.

I blame myself though. I ordered the wrong part from the wrong dealer. I should have ordered a "wr450f" from the guys up the street.


Sorry for drumming up bad memories but you have helped. Thanks. The klx has small tubes and O rings that move the oil through the journals. We suspected those could have failed but were confused by the oil standing in the head. Also the coating on the cams coming off causing problems else wear is interesting. Thanks again

  • GuyGraham

Posted September 03, 2014 - 08:43 AM

#28

After 80 hours are when my problems start with pistons on CRF or  KTM thumpers. So I'm planning on running the WR piston no longer than that.

 

You're comparing apples (or should that be blueberries) to oranges

 

 

 

 

 

 

Did my first piston change at ~400hrs (7000 dirt miles, most done on H&H or at practice track)

Piston looked fine, but it was starting to burn a little oil, so it needed rings anyway


Edited by GuyGraham, September 03, 2014 - 10:45 AM.


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  • Just_a_trail_rider

Posted September 03, 2014 - 10:41 AM

#29

I get 80 hrs. on the 530 and after that it uses too much oil on a ride to ride with any confidence. It also loses power around those same number of hours. Now this is true of the 530 which is my second KTM. On the other hand, no valve issues on the KTM after a couple hundred hrs. but the gearbox roached at around 130 hrs. My first KTM was the legendary 300, a 2010 XC-W, which I could not keep a piston longer than 40 hrs. without significant issues. This was arguably the biggest POS ever made.

Now CRF's are a different story. They'll run virtually forever once the heads are done right but after 80 hrs. on piston I've had trouble like cracked and broken pistons more than once and at least two occasions where that caused a snapped rod or smoked main bearings or both. So no more than 80 hrs. on a CRF 450 piston is a good general guideline which has served me well through several of these motors.

My last Yamaha was a 2003 YZ250. After I rebuilt it completely, it was virtually indestructible. Now I have the 2013 WR and I like it a bunch but for damn sure the piston will not be going any 200 hours. That won't work with the conditions I ride in or the type of riding and racing I do. So I'm hoping to get it torn down on schedule and the head sent off to AS Racing where Paul can port and immortalize the head:) When I get it back there will be new piston to go with it.

I feel ya!      

 

I was sitting pretty happy several years ago with my 05 wr450 and my 05 yz250.  I couldn't get either one of them to let me down.  The yz250 really liked new rings at about 100 hrs, which was 2 hrs and $40.  The wr... well...  it never broke down.  

 

Then I sipped the koolaid and went for a complete color change to orange.

 

I absolutely hated the ktm200 I had, although it seemed reliable.   The 450xcf, I think, is one of the biggest deceptions in motocycle history.  How could anyone sell a bike requiring that level of maintenance?  $5K in repairs in two years and less than 150hrs.   ON the other hand, my ktm300 is solid and runs amazingly.  It never breaks down and has a now rare Slaven's suspension.  

 

I got two kids in college right now, but I am hoping to bring some blue back to my garage in the next couple of months.



  • diekatze450

Posted September 03, 2014 - 01:32 PM

#30

My 2008 got piston,rings & pin at 300hours. Oil consumption and engine sound made me open it.

Also, there was -some- cylinder damage.(marks at lower and upper ends)

Could an earlier RING change help prevent the cylinder damage?


Edited by diekatze450, September 03, 2014 - 01:33 PM.


  • cubera

Posted September 03, 2014 - 02:30 PM

#31

You're comparing apples (or should that be blueberries) to oranges
 
 
 
 
 
 
Did my first piston change at ~400hrs (7000 dirt miles, most done on H&H or at practice track)
Piston looked fine, but it was starting to burn a little oil, so it needed rings anyway


I've seen quite a few roached older YZ/WR motors with less than 100 hrs. On the other hand, if I'm satisfied with what the ring lands and cylinder walls look like at the 80 hour tear down I might go longer next time. I'm getting close.

Edited by cubera, September 03, 2014 - 04:21 PM.


  • Just_a_trail_rider

Posted September 03, 2014 - 04:09 PM

#32

I've seen quite a few roached older YZ/WR motors with less than 100 hrs. On the other hand, if I'm satisfied with what the rings lands and cylinder walls look like at the 80 hour tear down I might go longer next time. I'm getting close.

I'll be waiting to see your report on this.  

 

btw... Paul at ASRacing was the guy I went to when I didn't feel like working on my wr.   But he was so good and so reasonably priced that I just couldn't justify working on it anymore.  When I went Orange...   he couldn't help me.   I haven't tried his suspension work...    yet....



  • cubera

Posted September 03, 2014 - 04:12 PM

#33

I'll be waiting to see your report on this.  
 
btw... Paul at ASRacing was the guy I went to when I didn't feel like working on my wr.   But he was so good and so reasonably priced that I just couldn't justify working on it anymore.  When I went Orange...   he couldn't help me.   I haven't tried his suspension work...    yet....


He did the re-spring and re-valve on my WR and it's like cheating. This bike is only out done suspension-wise by my beloved 2005 CRF450X RIP.

  • cubera

Posted September 03, 2014 - 04:20 PM

#34

My 2008 got piston,rings & pin at 300hours. Oil consumption and engine sound made me open it.
Also, there was -some- cylinder damage.(marks at lower and upper ends)
Could an earlier RING change help prevent the cylinder damage?


Yes assuming everything else was "in spec" a ring alone change would freshen the top end and help preserve the cylinder...BUT...IMHO if you're going that far you might as well put a new piston in while it's torn down. Pistons can look good and measure right only to crack down the middle from fatigue if it's exceeded its service life or worse.

  • cubera

Posted September 03, 2014 - 04:26 PM

#35

You're comparing apples (or should that be blueberries) to oranges
 
 
 
 
 
 
Did my first piston change at ~400hrs (7000 dirt miles, most done on H&H or at practice track)
Piston looked fine, but it was starting to burn a little oil, so it needed rings anyway


Lots of people do it this way. I never do rings only because I worry about a fatigued piston so I swap old for new. Overkill? Maybe.

  • mch

Posted September 03, 2014 - 04:35 PM

#36

Lots of people do it this way. I never do rings only because I worry about a fatigued piston so I swap old for new. Overkill? Maybe.

 

I always felt the same way.  If you are there already, you might as well fork out the $80-100 extra for the new piston.  Just the peace of mind is worth it, considering the cost it's going to be if your piston comes apart.

 

Unless of course you wanted to ride the next day and a piston circlip went flying while trying to install it.. :)






 
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