14 wr450 for motocross

[dslate]

Dude, a WR on the track will be worked just as hard as a YZF. Rebuild intervals would be virtually the same. Trail riding a WR would be considerably easier on the bike vs the track but the same thing can be said with a YZF. Reliability wise is a moot point...

mateninece is different. Although I don't go to mx tracks I will go to a 500 arce peice of land does actually include some jumps, bulldozer wild trails, single tracks, long straight a ways, and rough long stretchs of rocks. Plenty of points were you could about ride it like a mx track. But I font got the money to rebuild each and every year. With the WR's they can go forever without a rebuild. That's why I got one.

[Mcflyz450f]

Dude, a WR on the track will be worked just as hard as a YZF. Rebuild intervals would be virtually the same. Trail riding a WR would be considerably easier on the bike vs the track but the same thing can be said with a YZF. Reliability wise is a moot point...

Exactly, I have been on a dirt bike for close to 40 years and I have have rode almost everything from dirt to street. Track or not if you are bouncing off the rev limiter all the time your rebuilds are going to be more frequent. My last 07 WR had zero track time and I was super mellow on it and I had over 300 hrs on a top end. I never got that out of my track bikes ever but I revved this piss out of them also. Not here to argue any point but track bikes dirt or street are used harder then just trails or commuter riding. 

[Sp00na]

I've often wondered if the wr would last longer between rebuilds, I still change oil every 5 hrs ect, n clean air filter every ride, but I have heard the wr engine is very reliable, I just stripped everything from under the seat, see if it makes a difference next ride, was out at a track on the wkd n was keeping up with a group of racers so I was pretty happy with that for a wr, clearing all jumps pretty easy

[toten]

 

Dude, a WR on the track will be worked just as hard as a YZF. Rebuild intervals would be virtually the same. Trail riding a WR would be considerably easier on the bike vs the track but the same thing can be said with a YZF. Reliability wise is a moot point...

Exactly, I have been on a dirt bike for close to 40 years and I have have rode almost everything from dirt to street. Track or not if you are bouncing off the rev limiter all the time your rebuilds are going to be more frequent. My last 07 WR had zero track time and I was super mellow on it and I had over 300 hrs on a top end. I never got that out of my track bikes ever but I revved this piss out of them also. Not here to argue any point but track bikes dirt or street are used harder then just trails or commuter riding. 

Doesn't the YZ have more aggressive cam profiles than the YZ? That will wear out the valves faster no matter how you're riding. I don't remember if there's a difference in valve material, but that could also explain a difference in wear. 

 

Commuting can be hard on a thumper if you do much freeway and aren't geared for it. There's a reason why I'm running 14/40 on my SuMo, and it still doesn't particularly enjoy freeway. 

[Mcflyz450f]

 

 

Commuting can be hard on a thumper if you do much freeway and aren't geared for it. There's a reason why I'm running 14/40 on my SuMo, and it still doesn't particularly enjoy freeway. 

 

I agree if you just stay at the the same rpm's for long periods but when you are practicing then running your race you on that rev limiter all the time parts wear fast. Same hour for hour on my bikes, track bikes always needed more maintenance work then my bikes I had plated. I also didn't rip down the freeway for long periods either. 

[msawyer420]

Lol your arguing that a yz is as reliable, and had similar maintenance to a W.R. you couldent be further from the truth. A mx track doesnt make a yz require more maintnence its the 4 valve head lol. Dont even try to argue a yz will touch a wr in terms of this. I know people with wr's with over 20,000 miles on the factory top end.

[Hans Schmid]

Lol your arguing that a yz is as reliable, and had similar maintenance to a W.R. you couldent be further from the truth. A mx track doesnt make a yz require more maintnence its the 4 valve head lol. Dont even try to argue a yz will touch a wr in terms of this. I know people with wr's with over 20,000 miles on the factory top end.

You start riding a WR on the MX track and let me know when you hit 20,000miles, it just ain't going to happen. Riding a MX track is harder on the motor then any trail riding, period!

[chu]

Why would a 4 valve DOHC be less reliable than a 5 valve?  Bigger, heavier valves?

[msawyer420]

The engine is still a five-titanium-valve unit that Yamaha says it prefers to stick with rather than a four-valve configuration because it offers superior reliability. Who are we to argue? The record stands for itself on that one.

Straight from Yamaha via dirt action website. You can call Yamaha and they will tell you straight up maintence and reliability of the WR is far superior. Its meant to be riden every day of the year. Once you pass a certain power level on a 450 jug you stress out the working parts, hints the 5 valves.

[Mcflyz450f]

The engine is still a five-titanium-valve unit that Yamaha says it prefers to stick with rather than a four-valve configuration because it offers superior reliability. Who are we to argue? The record stands for itself on that one.

Straight from Yamaha via dirt action website. You can call Yamaha and they will tell you straight up maintence and reliability of the WR is far superior. Its meant to be riden every day of the year. Once you pass a certain power level on a 450 jug you stress out the working parts, hints the 5 valves.

The five valve head is not superior to a 4 valve head, if it was then they would have kept the 5 valve head on the R1's. I have a 2012 R1 and 2015 WR450 so I have both. Yamaha switched back years ago, R1 forum article on it http://www.r1-forum.com/forums/2-general-motorcycle-discussions/226887-whats-better-4-valve-5-valve.html

 

5 valve heads are old technology and so is the motor in the WR.

[msawyer420]

You win

[msawyer420]

What does an r1 motor have to do with a 450cc single cylinder combistion chamber running the exact same rpm's. Nothing. Each cylinder in an r1 is 250cc hints why a thumper has to be rebuild more than a crotch rocket. Way to compare apples to oranges. Were talking about large cc single cylinder motors here bud. Way to switch to a 4. Cant wait to see what you come up with next. You can read directly from Yamahas site about how reliable the Wr motor is, they do not mention a thing about the yz in regards to longevity. Just give up man, its well known through the community! You could even post this in the yz discussion and they will tell you the exact same thing. Find something better to spend your time on!

[msawyer420]

And btw, reason the r1 and yz both have 4 valve heads is to save weight. Good enough answer for you? Probably not haha

[Mcflyz450f]

I was just pointing out how wrong you are about 4 valve vs 5 valve. The WR has a old YZ motor, it's old technology and not anymore reliable then a 4 valve head. Why isn't all other bikes on a 5 valve set up?? It's 90's technology at best, so stop giving people false info. I'm glad you can read articles on the internet but start reading them from this time and age not the 90's.

[Mcflyz450f]

Once again it's not just weight, but angle, compression, performance. 

[msawyer420]

Your arguing with Yamaha the maker of the machine in question. Why not ask them? It is them who is claiming its better. No need to say im claiming false information when im simply copying and pasting Yamahas direct quotes.

[msawyer420]

Liquid-cooled, 4-stroke, single-cylinder, 5-valve, 449cc engine

In the enduro and trail world the WR450F’s liquid-cooled 4-stroke engine has achieved legendary status for its durability and reliability. With its 5-valve cylinder head and new fuel injection system, this powerplant pushes out strong, useable and linear performance hour after hour.

Another quote directly from their site, went and tried to find the words reliability and durability in the yz450f specs and ya know. I guess they just forgot to mention that. Furthermore you say that the 12'-15' wr450 motor is an old design? Thats funny because it was completely re-designed to fit the 250 frame huh interesting. Ever taken your case cover off and noticed its the exact same shape as the frame? Guess not, you should do some reading. I guess you didnt know its not the same motor. Im here if you ever need any info!

[SteveThe Snakes]

The Yamaha's have all been pretty much very reliable that includes the first YZ400f and the WR's to the latest. They last many older ones are still in use and that should equally include the new ones later in life.

4T's usually suffer from valve issues and Yamaha has had down a very reliable shim under the bucket design. First perfected on their street bikes and carried over to the first YZ400f dirt bike.

[RockerYZWR]

Don't forget, with all the quotes from Yamaha's website ... Marketing people write all that and they're trying to sell you a product. Sure, the WR450 is reliable - we all know that - but compared to what? And what is the actual measure of reliability? They leave all that out because the second you start quantifying it, it'll make it sound unreliable to the average dude reading the marketing hype. It has to be put into context to really mean anything. It's marketing drivel.

And in my opinion, omitting the word "reliable" from the YZ ad doesn't imply unreliability; it's a race bike and the going in understanding should be that a race machine, run under race conditions, will require way more maintenance than say a WR450F, or even another YZ-F, or a TTR250... run under non-race conditions. If you followed the WR450 service manual's race maintenance intervals to the letter, you'd probably consider hiring a full time mechanic.

[chu]

The '15 WR250F got the 4 valve backwards motor.  I think it's a safe bet that the next gen WR450 is gonna go that way too.