New school 4-strokes - severe maintenance?

[WR 250]

New school 4-strokes - why the severe maintenance?

I haven't been keeping up with dirt bikes since I bought my KDX back in 2000. I used DRN as a valued resource to determine which bike to buy. Since I'm in Alaska, I'm far more familier with snowmachines (snowmobiles) and have converted over to a 4-stroke Yamaha sled with no regrets.

My question is, my Yamaha snowmachine doesn't have intense maintenance requirements. The first valve adjustment is at 25,000 miles and oil changes happen once per season. Why do the new 4 stroke dirt bikes require so much maintenance? Is it just OEM recommendations? My KDX owner's manual recommended that I remove the carbon from my piston after break-in. I doubt anyone in the world actually did that.

 

[XRpredator]

your snow cat has more than one cylinder, which could contribute, and is probably built a little heavier than the single cylinder motocross steed powerplant.

Then again, I don't see our modern 4-strokes as that maintenance intensive. All you gotta do is keep an eye on things and it's all good.

 

[headbanger]

Your sled has a similar motor to the R1 sport bike and yes they are very reliable. The
"New" 250F dirt bikes are very light weight and high RPM and carry very little oil in the crankcase. I have five riding buddy's who have or had 250F's and all have had valve
trouble. Two of them went back to 2 strokes and another is going to a KTM450.
I wonder how the new Phaser motor will hold up since it is two YZF250F motors build
as a parallel twin. A local sled shop modified 5 new phasers with Turbo's! I guess they are a blast to ride!

 

[SFO]

I think the maintenance schedule should have a sliding scale for cowtrailers.
I have a regular riding buddie that has a '98 yzf400 that has NEVER been serviced.
I believe the yamaha to be the most bomb proof 4st.
IMHO

 

[WR 250]

The new Phazer is a good example of a snowmachine not having the same maintenance requirements as the dirt bike it is based off of. Seems to me that because I could easily run the Phazer motor much harder than in a dirt bike that a sled motor based off two 250F top ends would not be a good idea. In AK you can easily run a sled at WFO for literally minutes on end. Combine that with lots of resistance from deep snow and climbing up a steep incline on a glacier, seems like that would put some serious strain on a motor. I don't live where I can run a dirt bike in the same manner so I'm wondering why do the bikes experience problems? Is it simply a matter that more 4 stroke dirt bikes are sold than 4 stroke sleds so the odds of bikes having problems is greatly increased?

I believe the Phazer also has the 25,000 mile valve adjustment. XR, your right, my Vector has a big, realtively heavy 3 cyl motor.

 

[destructo]

Because I don't motocross and just fast trail ride, ive gotten ridd of my yz450 and gone back to the old tried and true R230 awesome bike and can keep up with just about any one, Ive rejetted and piped, new clutch and just did the first valve adjustment tonight it ripps and is virtually maintenance free. And it still has the good ole fat 2 valve motor (easy as crap to adjust) If you dont race pro you dont really have much maintenance, I change my oil kinda excessively every sunday night but thats just my thing, keeps it like new inside. :nod: