When to replace Wr450f piston and rings?!

[Adamridesorange]

Anyone?

[miweber929]

Anyone?

Anyone what? We answered the question, the piston needs to be replaced after 200 hours or you are working on borrowed tine. If you want anything more than that go lower performance like a DRZ or Honda XR. Whether you are "easy" or not on the motor really doesn't make much difference, some, but not enough to completely change the interval.

Not what you want to hear but it's the truth. Sorry man.

[Adamridesorange]

Sorry, I didn't realize any one ever answered it.

[3MTA3]

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.

It is definitely "safe".  Am I going to change mine out at 200, nope.  But that is me.  Prolly closer to 300.

[wizbangdoodle]

I've got an '07 WR450 and am still running all stock stuff.  Purrs like a kitten and pulls like a beast.  I do regular maintenance and ride mostly woods (slower stuff).  I'm also old, so I don't rev the piss out of it and beat it to death.

[jackiefresh69]

Just piping in here

I have done about 200 hard hours on my 04wr250f and who knows how many the guy before who had it did and she's still perfect ?

[3MTA3]

All good reasons why I don't really like to put a "specific" number to something. Learn to feel, hear how your bike is running and you should hopefully be able to notice a drop in performance. This could be naive, but that is how I have done it. The only reason I had mine done was I wanted to put in the YZ cams and do a bit of porting. Was looking to get a bit more umpf. My motor guy actually wanted to use a couple of the valves. I said no, replace everything, we bumped up the piston by .5. Been very happy with it.

[Adamridesorange]

It seems here that the wr250s need top ends a lot sooner then the 450s do. Most people are doing them around 60-70hrs...

https://www.thumpertalk.com/topic/647689-how-often-to-replace-piston/

[Adamridesorange]

And do you think it's safe to go 300 hrs...that seems like a lot, considering a lot of people are saying to do it at 200...?

[Adamridesorange]

Or when you say "closer" to 300 hours...do you mean more like 250-275?

[SteveThe Snakes]

In the olden days bikes used to smoke when they needed a new piston and rings. wha happened to that.

[grayracer513]

250's spin more revs per mile, and so wear out sooner.  If you stop looking for hard numbers (which don't exist) and go back to what I said about using leak down tests to evaluate the condition of the cylinder, you'll be better off.

 

In the olden days bikes used to smoke when they needed a new piston and rings. wha happened to that.

 

Three piece oil rings.   Besides, it takes only .003cc of oil in the combustion chamber with each firing to burn 500cc of oil in an hour.  Not much smoke in that.

[beezer]

The OP should buy a WR450 and ride until it blows up.

 

Then change the piston an hour sooner.

[Adamridesorange]

Well all I was wondering was, someone said they will go closer to 300 hours, and I was wondering if by "closer" he meant 250-275ish, or if he actually went to 300 hours which seems like a lot.

[3MTA3]

Well all I was wondering was, someone said they will go closer to 300 hours, and I was wondering if by "closer" he meant 250-275ish, or if he actually went to 300 hours which seems like a lot.

It sounds like you are getting frustrated because you want someone to give you a definitive answer on what they recommend and then you will go by that.  IMO, I just wouldn't do that.  Any recommendation you get should still be just that, a recommendation, a "ball park" to start to think about it.  Then you can pay closer attention to how the bike is acting, sounding, riding.  Is it different then it has been.  Is it harder to start, things like that.  The hours thing will just get you to a place, not necessarily to THE place.

 

This is just my opinion though.  My WR has been a rock solid performing motor ? 

[Adamridesorange]

Alright sounds good, and I'm not saying I'd follow any of these recommendations out...but look at this, I don't even understand how some of these numbers are possible...https://www.thumpertalk.com/topic/1030457-wr450f-max-hours-on-engine/

[Adamridesorange]

TheKoolAidMadeMeSick...you said on here that at 200hrs you get some slap/rock..but in the post above you said that you can go 300 easily and you said you even went as far as 600hrs...is that without even a piston change?

[SteveThe Snakes]

Upon the first piston change a good forged American three ring piston might go and go and go in a hard chrome bore. Till your sick of riding an old bike.

[Adamridesorange]

And also does anyone know if the common "free mods" affects the rebuild interval any? According to this the stock wr is very restricted to allow it to be very reliable http://motorcyclejazz.com/Yamaha_WR450F.htm. Once the free mods are done and the bike is able to open up more and is making more HP, does it shorten the piston and ring life any?

[grayracer513]

The bike is very restricted to allow it to get a Green Sticker in California and other socialist countries.  Doesn't have a lot to do with building in reliability.  On the other hand, there is no fundamental difference in 90% (or more) of the core parts of the engine between the WR450 and the YZ450F (Gen1 and Gen2) and the WR.  The WR produces 15% less power, and for the most part fills a completely different role than the YZF, which routinely run over 150-200 hours.  Why wouldn't it be nearly indestructible?