Tell me about the 2004 YZ125

Spares of what ? I have the 5 speed 2002, it's been a solid bike.

The suspension does leave something to be desired stock, but a spring and a revalve makes it livable. My bike went through a stator, not sure if that's common. As far as power, well it's a 125. But it's very very nimble and fun to ride.

My plan is to build it up with rpm's 167 kit eventually and keep it as a spare , ride once in awhile bike.

I have one that I've been riding for the past few years, solid bike lots of grunt has the 48mm fork same size as the later sss, ti pegs
I prefer the feel of the steel frame over the later aluminium ones (have owned both) spares are pretty cheap but they are pretty much bulletproof, does have the old style front brake cable routing which isn't the best but can be modded

very good bike but quite big difference to the SSS suspension. The SSS fork legs fits right away.

from a magazine:





The bottom-end of the power range felt a bit weak for my liking, though the extremely loamy track played havoc on the Y-zinger. However, one tooth larger in the sprocket made life grand. The new YZ motor has more midrange than any other 125 I have ridden. It revs out like last year’s bike but seems a bit harder to keep on the pipe. The fork is awesome; I tried unbolting a set to take home, but the Yamaha guys didn’t find that so funny. The suspension and handling on the Yamaha are impressive. The new, larger fork gave me a feeling of confidence when trying jumps for the first time, mainly because bottoming is no longer an issue. The brakes are as terrific as they have been in the past. The rider compartment feels very comfortable and is roomy enough for my height and riding style. With a few minor changes in jetting and gearing this bike would be a very potent race weapon.
Brad Daugherty/6’0″/165 lb/IntermediateThe 2004 YZ125 wasn’t all that different from the ’03 model. The only big changes that I felt were from the bottom- and top-end performance and the fork. The motor still has a strong pull down low, but it is not quite as good as the ’03 version’s; the midrange is really wide and can be shifted early. The ’04 also seems to pull longer than the ’03. So it is a give-and-take. The ’04 YZ125 is more suitable for faster riders. The bike is so much better with the 48mm fork on it. It can handle slap-down landings without that dreaded clank Yamaha owners are used to. The bike also soaks up small chop a bit better. The shock is good but may be a tad too soft for my liking; a heavier spring will do. The ergos remain good and the graphics still look wrecked after a couple of rides. All in all, the 2004 edition is a little better.
Kris Keefer/5’11″/170 lb/ProThe ’04 YZ125 feels like a full-on race bike right out of the crate, with the exception of the missile on the bike that all manufacturers call silencers. This could possibly be the best stock 125 I have ever ridden. With a few carburetor adjustments and a 50-tooth rear sprocket to replace the 49, the bike pulled hard and strong throughout the powerband. The new Kayaba 48mm fork that replaced the old 46mm is icing on the cake. The suspension couldn’t be better. If I had to race the bike, I would leave the valving and clickers bone stock, that’s how good they are. The new YZ will be a threat in this year’s shootout.
Levi Reid/5’10″/160 lb/Pro

great bike IMO. They revamped that engine in 2005 along with the aluminum frame. I've ridden both, and although the 05' and up motor seems easier to keep in the powerband, the 04' seemed to have more power up top and more over-rev. Probably because they spec'd a shorter connecting rod in 05', and some porting and ignition changes.
Yes, you can upgrade to the later SSS forks, but you need at least the triple clamps also.

The hub is identical but the spacer may need to be changed. Almost sure that the triples are the same also since the 04 forks are 48mm also. Otherwise stock clamps are cheap on ebay and the steering bearings are identical.

Ufo restyled kit fit's 02 and up.2015 plastic bolt's right up apart from the front fender and plate.easiest way is to use ufo or cycra front fender and plate (small mod maybe required for the plate) and 15 stuff for the rest or just get the full ufo kit.lightspeed do a kit with the newer brakeline routing and more up to date lower fork guards.
http://www.lightspeedcarbon.com/ProductDetails.asp?ProductCode=141%2D17…

Not sure,it was just a pic i used from thumpertalk so people can see it works with the steely model's .

looks like you could get lost in there !!!!

Thats that backside of my messy garage! lol I've got enough spare parts laying around and in those boxes to almost build a couple of bikes...

And thats my son's YZ.... he's got new front plate, shrouds, and graphics coming for it soon, so it'll look right.. Its an 04' 250 with SSS suspension, oversize front brake, and 15' plastics.
And yeah, the 15' stuff bolts right on for the most part.

I have a friend with a stock 03, solid bike but it has sort of a weird, delayed hit. Nothing nothing nothing and then boom, very hard and short hit. I have a LOT of 125 time over the years, but this one is different and difficult for me to come to terms with. I've read that the 04 had a different governor spring in the powervalve and it helpe move the hit down a little.

Chassis-wise they are very nice and still feel pretty modern. Bars feel sort of up high compared to my CRF (and it's not just the bar size). I think a revalve or ideally swapping the forks for some SSS units would make it a great bike.

I have had two 04 125s. Great bike. Super good motor and steel frame.

Go with a vforce, fatty pipe and shorty silencer.

I went with a 49 tooth rear and one leaner on the main jet. Not sure what sea level you are at. I would get new power valve springs and clutch springs. Go through the linkage, the lower pivot of the shock gets abused so that would be something I would go through.

If you can get the SSS forks, you will be set. Those are by far the best forks you can get off of the show room floor. So spend some time and find them on ebay and convert the front end.

I spent maybe 1000 dollars on everything for my bike and that was with wheel bearings, full top end, etc.

My bike is in the bike check if you want to take a look at it, ask me questions and I will try to answer what ever I can.