HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
cleonard

Piston lifetime for a XR600

10 posts in this topic

After talking to a friend who was doing his yearly piston replacement on a CRF bike, I started wondering about the XR600. When is it time to replace the piston? I've been into my engine a couple of times and the piston has always measured as new even though it has a lot of hours on it. I've been riding it 60 or more times a year and it still has the same piston as when I got it in 2000. It's not the stock one that it had in 93, so it is at least seven years old and maybe more.

Do theses pistons ever break off a skirt? Is it time for a new one before metal fatigue causes the skirt to break? How many hours is too many?

Share this post


Link to post
Share on other sites
After talking to a friend who was doing his yearly piston replacement on a CRF bike, I started wondering about the XR600. When is it time to replace the piston? I've been into my engine a couple of times and the piston has always measured as new even though it has a lot of hours on it. I've been riding it 60 or more times a year and it still has the same piston as when I got it in 2000. It's not the stock one that it had in 93, so it is at least seven years old and maybe more.

Do theses pistons ever break off a skirt? Is it time for a new one before metal fatigue causes the skirt to break? How many hours is too many?

it all matters on how you maintain the engine. I would look into it when one of the following happens (in no particular order):

  1. Piston slap
  2. Smoke
  3. Loss of power
  4. High oil consumption
  5. High fuel consumption
  6. Your weiner falls off

Share this post


Link to post
Share on other sites

It's an XR. I'd go with number 6!

In all seriousness, as long as the piston AND the cylinder are in spec, you will have nothing to ever worry about. The skirts will only break if there is excessive piston slap, and that is not a common problem. I've seen old XR500s that are used, abused, and still using the stock piston.

The only reason to put in a new piston is when you overbore the cylinder and put in a bigger piston to make it a 630.

A CRF and a XR are completely incomparable in terms of engine longevity and parts replacement schedules.

Share this post


Link to post
Share on other sites

i also am in agreeance with #6. also piston slap is the main 1 to look out for. as long as its within serviceable limits, all good!

Share this post


Link to post
Share on other sites
i also am in agreeance with #6. also piston slap is the main 1 to look out for. as long as its within serviceable limits, all good!

What is piston slap?

Share this post


Link to post
Share on other sites
What is piston slap?

piston slap is an upper end piston "knock". it happens when the piston skirt to cylinder wall clearance becomes excesive. the noise comes from the piston rocking side to side(in small amounts, not talking about much here) and causes a sort of hollow, upper end knock.

Share this post


Link to post
Share on other sites

I guess that I'm good then. Last year I was blowing oil out the breather. When I opened her up the rings were completely shot. The end gap was about .150". The piston measured new. After honing I still had .001 to go on the piston to bore clearance before it was too big so I just popped in new rings. She has been a one kick starter ever since.

I remember the first time I saw/heard a CFR450. The thing was slapping like crazy. I even said to the guy "that thing makes a lot of piston slap how many hours do you have on this bike?" He said "this is my second ride."

Share this post


Link to post
Share on other sites
I guess that I'm good then. Last year I was blowing oil out the breather. When I opened her up the rings were completely shot. The end gap was about .150". The piston measured new. After honing I still had .001 to go on the piston to bore clearance before it was too big so I just popped in new rings. She has been a one kick starter ever since.

I remember the first time I saw/heard a CFR450. The thing was slapping like crazy. I even said to the guy "that thing makes a lot of piston slap how many hours do you have on this bike?" He said "this is my second ride."

no wonder they are O/H constantly!

Share this post


Link to post
Share on other sites

I had an 1986 XR600 that developed a knock and the wristpin had developed play between it and the piston after about a million miles. Cylinder was still in spec. a wristpin and piston and it was back on the trail as a loaner/guest bike. That was after 7 years of abuse.

Share this post


Link to post
Share on other sites
I remember the first time I saw/heard a CFR450. The thing was slapping like crazy. I even said to the guy "that thing makes a lot of piston slap how many hours do you have on this bike?" He said "this is my second ride."

The other thing to remember with a CRF is that the piston really has no skirt to even start with. It is nearly a flat chunk of aluminum with a spot for the piston pin and rings. This is to minimize piston reciprocating mass to allow the motor to rev much faster at the expense of service life (obviously).

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0