03' yz 450, possibly has a flywheel weight?

Hey everyone. I just got a 03' yz 450, and i love it. But one thing, i dont think it has the power it should. From what i heard, these 03's were nuts!:crazy: I just came off a 125 and expected to be very affraid of this thing, do you think it might have a flywheel weight? It hasnt been raced, it was trail ridden so i think it might. Any input would be apretiated.

oh, and it also seems rather quiet, it is supposed to be 103 db or somthing, im pretty shure it is not anywhere near that. Any ideas?

When I first got mine, I came off a CR500, and I couldn't understand what all the fuss was about. You can tell if the flywheel is weighted or not by pulling the upper timing plug. The stock flywheel is cylindrical, whereas any of the weighted ones have a more conical appearance, and you usually won't be able to see a timing mark.

As to the noise level, there is a marked difference between what you hear on the bike, and what it sounds like to the rest of the world. Might look into that.

When I first got mine, I came off a CR500, and I couldn't understand what all the fuss was about. You can tell if the flywheel is weighted or not by pulling the upper timing plug. The stock flywheel is cylindrical, whereas any of the weighted ones have a more conical appearance, and you usually won't be able to see a timing mark.

As to the noise level, there is a marked difference between what you hear on the bike, and what it sounds like to the rest of the world. Might look into that.

"As to the noise level, there is a marked difference between what you hear on the bike, and what it sounds like to the rest of the world." :applause: :applause: :applause: :applause:

hmm il check for the weight, and as for the noise, i did check into that, my dad took it for a lap, and yes it is rather quiet.

oh, and if it did have a flywheel weight, would it tame it down that much that is would make me think it had one? Even though i have never rode another 450?

The best way to imagine how a flywheel affects a YZ450 is to think of an 8 oz weight as making like it was in a half gear higher than it is. Doesn't slow them down so muxh as make them controllable.

What exhaust does it have?

i would say u most likely have a fly wheel weight cuz mine has threw me off a time or 2... now im far from good/experenced so im sure that has alot to do with it but the kx250 with much work done to improve the low end does not compair to when my 450 kicks in... now that may just be the nature of the beast but i am a 210+lb rider and now matter how far forward i put my weight it still picks the nose up at a 1/4 throttle threw all 4 gears..... now i was told when i bought the bike from a "well respected" dealer that the prior owner had set it up for racing and hurt himself on it and no longer could ride....... i haven't seen any "aftermarket" mods buti also have no idea what would look different.... at any rate judging by what u have said i would say u deff got a weight in there if not some other form of restrickion..... i was thinking of puting a fww cuz i really only ride trls but ive almost gotten used to brunt it has and have caught myself relying on it a time or 12:thumbsup: :thumbsup:

Hey everyone. I just got a 03' yz 450, and i love it. But one thing, i dont think it has the power it should. From what i heard, these 03's were nuts!:crazy: I just came off a 125 and expected to be very affraid of this thing, do you think it might have a flywheel weight? It hasnt been raced, it was trail ridden so i think it might. Any input would be apretiated.

A good riding buddy of mine had an '03, and that was the pinnacle of Yamaha's BRUTE 450 engines. Thereafter Yamaha started making their 450's more "friendly" to ride.

My buddy spent severall months trying to adapt to the nasty snap and torque right off the bottom on his '03, but never felt comfortable, he added a Steahly flywheel weight and was amazed at the difference in low end traction and drivability. You also DON'T loose power from adding a flywheel weight, you simply "stretch out" the rpm and torque curve making it more linear. I have one on my KX500 and absolutely love it. My '07 YZ450 feels just like it has a flywheel weight! :thumbsup:

i recently put a weight on my 450 and i love it

i can ride the hell out of my bike now

My '06 is fine without one. My '03 has an 8 oz Dr.D in it, and this is the flywheel it should have come with from the factory, IMO.

yeah my 04 needed it

does the weight really slow the bike down?

if the weight is bigger does it make better traction ?

The weight slows down the RATE of engine acceleration. That is, the engine will not "spool up" as quickly as if it had the stock (lighter) flywheel weight. On the 03'-04' models, an aftermarket heavier flywheel weight is definitely a help with keeping the rear tire spinning out during acceleration, and helps to keep the engine chugging over on slow, twisty trails (especially going uphill).

My 04' when ridden on tight, twisty, uphill trails with the stock flywheel, was prone to stalling. With adding a heavier flywheel, the bike keeps running and gets better traction.

does the weight really slow the bike down?

if the weight is bigger does it make better traction ?

The additional flywheel weight makes it more work for the engine to accelerate its own mass. Its effect on an engine depends on what the engine was like to start with. An engine like the '03-'04 YZ450 starts out with the capability to break the rear tire loose so easily in the first two gears that it is difficult to control, and demands a great deal of attention when powering out of loose spots trying to get the tire to hook up.

Where the heavier flywheel is most obvious is when you're in the poorest traction at the lowest speeds. The bike will bite, raise the wheel, and accelerate in the same spot where it used to sit and dig a trench. The added rotating mass has no real noticeable effect on acceleration in the higher gears at all, so often times, rather than slower, the heavier flywheel actually makes the bike quicker.

alright thanks everyone. I still think it has a fww, but i am more used to the way the power works now, so im going faster now. I was trying to ride it like my 125...

I have a 03 450F with a fly wheel weight. It is much more ridable and still a very fast machine.

One way to tell on my bike is the addition of a gasket or spacer over the fly wheel case. The shim or spacer is required in order to accomodate the additional size of the weight.

The shim or spacer is required in order to accomodate the additional size of the weight.
This is not true of the bulk of the heavier flywheels or weights available.

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