Full throttle

[thelake]

Hey everyone.

I opened up my sled yesterday.
I hit 127 kilometres an hour.
I hammered the throttle for about an hour. Regularly doing 110-120.
My buddy says the engine is built for all day full throttle experience.

Your thoughts?

 

[Mooseman]

Any engine running at full power will eventually fail, especially one screaming at 11-12k RPM. However, this engine is based on Yamaha's YZ250F dirt bike engine so it wasn't designed to be at full throttle all day long like a street bike. Only way you can have a long distance full throttle run would be on a really long lake or river.

I've taken mine to 125 km/h on really straight, flat and packed trail. And that's with my 6'2" 300+lbs. carcass. Pretty impressive really. Wouldn't surprise me if it could go to 14o with a horse jockey on it.

 

[YukonMP]

Well, as I recently mentioned elsewhere I did just make a long lake run, 100km one way. I too held it to the bar for a couple stretches of a minute or two but in the heavy slush I only saw 80ish and 10400. Personally I wouldn't run Blue any harder than that. If the engine was revving higher with less resistance I'd back off sooner. I wouldn't do extended high rpm runs unless the cooling was optimal. In my case we were in continuous slush.

A major consideration after the cooling is the oil. Blue was running 0w40 with less than 200 kms on it. Our sleds call for 0w30 but I'm quite comfortable with the heavier oil, especially in the spring when running hard. We have no way of knowing the weaknesses in the performance of our oil and oiling system under such extreme use, ie.viscosity breakdown, foaming, etc.

Bottom line, for me, a premature engine failure is not worth the risk. And it is not as if any of the rest of the sled is immune to being maxed all the time. Belts, clutches, sliders, idler bearings, the exhaust system, bushings.

If I sound like an old man that is because I am. I depend on my sled for transportation and take pride in safety, economy and reliability. All that said do what you are comfortable with knowing a Yamaha is likely to take a lickin' better than most.

 

[Mooseman]

And just so you know, you can't over rev it as the ECU will limit it to about 12.5k RPM. My son's Phazer has a clutching or gearing issue and regularly hits the rev limiter.