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jobob303

09 yz450f

11 posts in this topic

Hi i am currently looking at upgrading from a 03 wr450f to a yz450f as i have started riding more motocross than i ever thought i would :banana: and i am looking a an 09 yz450f it has 44 hours on it and never been raced and i am wondering how often they should be rebuilt?

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That depends on how well it was maintained. However, these motors are pretty reliable. Idk about prices in AUS but here in the states you can buy a new 09 so cheap its worth it to just buy a new one! 44 hours isnt that much, if it was well maintained and if the valves are in spec or never need adjustment you should get many more hours out of it.

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I'm at 45 on my '09, I'm holding out for 100 before I rebuild it. We'll see how it lasts, I've heard others get this much and say it still looked great when they tore it down.

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ok thanks guys, my brothers mate whos a motocycle machenic said that they should b rebuilt around every 60 hours but i sapose if its been well maintained it should do 100 :banana: but we will have to see how the funds are after i get rid of the trusty old wr

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I think guys who can race these things at the limits are the ones needing the frequent rebuilds. I race MX with a bunch of 40+ guys and none of them are rebuilding that often, not even the fast guys in the master class. Some of them have deep pockets, though, and just buy a new bike when they think it's time. Must be nice....:eek:

I'm more of a 'middle of the road' kinda guy on how hard I race my bike. It's never even seen the rev limiter with me on it, I'm pretty confident I can hold out for longer than 60. :banana:

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What if you don't know how many hours your motor has on it? I just bought a used 2008from a guy that got it from someone else and claimed it had 9 hours on it. I'm guessing it has more than that just looking at the wear on the tires. The oil looks clean and the rest of the bike is i great shape. I don't ride it that hard as I don't race. Mostly trails and fooling around on tracks. Even airplane engines run for 2000 hours before the manufacturer recommends an overhaul. When you say "rebuild", what does that entail? Rings, piston, hone the cylider, valves, etc.? Anything on the bottom end? How much would what you're talking about cost?

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What if you don't know how many hours your motor has on it? I just bought a used 2008from a guy that got it from someone else and claimed it had 9 hours on it. I'm guessing it has more than that just looking at the wear on the tires. The oil looks clean and the rest of the bike is i great shape. I don't ride it that hard as I don't race. Mostly trails and fooling around on tracks. Even airplane engines run for 2000 hours before the manufacturer recommends an overhaul. When you say "rebuild", what does that entail? Rings, piston, hone the cylider, valves, etc.? Anything on the bottom end? How much would what you're talking about cost?

Most the times they mean rings and a piston for a two-stroke and same for a 4 but may also mean the valves need to be looked at while you are in there.

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Even airplane engines run for 2000 hours before the manufacturer recommends an overhaul.
Airplane engines lead a ridiculously easy life, too. In the first place, they're exceptionally overengineered as a safety matter. Secondly, they don't work very hard at all.

The Continental O-470-11, for example is a 1500 hour engine. It's a 7.8 liter six cylinder that produces 213 hp at 2500 RPM. That's 27 hp per liter at max output, and the engine will spend very little of its life maxed out. Probably cruises at much less than half that power level.

On the other hand, a YZ450 produces around 50 hp at 8500 RPM; 111 hp/liter, and spends a lot of it's time in acceleration under heavy loads at high speeds.

What wears an engine out is horsepower /hours per liter. In other words, how much horsepower has it produced relative to its size for how long. It's the only true gauge of the load on an engine.

From that, you can see how much it matters how the bike was used when considering when to rebuild. If all it ever does is have a pro race and practice on it, it's going to need to be looked at every 50 hours of actual time or so. If it's mostly a recreational ride, I'm not sure how long it will go. I've seen YZ450's at 300+ hours that were never touched outside of basic maintenance.

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I Know when I sold my 2006 450 around 4 months ago it had 101.00 hours on it.

I had my buddy to put a piston and the rings in when it reached 50 hours.

i raced this bike at the tracks and practiced on it also at the tracks. I hear when you put a piston and rings in to go ahead and put a timing chain on but he said the chain looked good and wasnt wore any. he also said the piston wasnt worn any either.

The boy i sold the bike to has now put 5 more hours on it and puts the same oil I used in it (Amsoil 10w-40w mcf). He changes the oil every four hours to where I changed it every 1 and a half hours (roughly after every race of 2 classes).

My friend that has the yamaha shop said these 2010 450's were suppose to last longer (piston,rings) where he got this info I dont know.

So the way i look at it is.........If I got 50 hours on my 06 before I put a new piston and rings in I should be able to go to 70 hours or longer on this 2010 450.

Maybe my 06 held up good cause i kept good oil in cleaned the stainless filter and changed the air filter after each race and ride. Who knows but I'm glad I got to ride that 06 for that long without any engine problems.

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Like Grey said it really depends on the rider. How often the oil is changed also makes a big differance in the longevity of these bikes.

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