2003 yz450f

[yamaha450777]

hey guys, new to the site and 4 strokes... i just got a 03 yz450f today, stock except fmf 4 pipe and powerbomb header , and i have some questions, i heard that your not suppose to use the clutch when shifting. is that true? what are some things i should check before riding it. The guy i got it from bought it last year from the original owner, he didn't know if it had ever been rebuilt.

[TIG88]

Congratulations on purchasing the beast!

Change the Timing chain, I use the clutch when I shift, and it wouldnt hurt if it had a top end, I'm doing mine shortly, it will be its first. Also check the valve clearence.

Also, the header will glow red if you let it idle for 30 seconds

[yamaha450777]

how often do they need a top end? what are all the parts that need replacing, and about how much? should i get oem parts or aftermarket?

[426 NOOB]

how often do they need a top end? what are all the parts that need replacing, and about how much? should i get oem parts or aftermarket?

They dont need one very often, some people have over 200 hours on stock tops, but others change them every 60 hours. It all depends on how hard it is ridden. but it is a good idea to change the cam chain every year or two depending on how hard its ridden as well. Personally I would go oem. The stuff lasts forever. You will need timing chain, piston, rings, and gasket kit. Hopefully thats it. that is if the cylinder is in good condition. Others will add what I missed. I want to say with oem components it would run about $ 300 maybe a bit more. Make sure you run a good oil like amsoil or mobil 1 motorcycle grade, and change it every 6 or so hours of seat time.

[TIG88]

Personally I would go oem. The stuff lasts forever. You will need timing chain, piston, rings, and gasket kit.

Go to the TT store. Get a piston, rings, piston pin, head gasket, base gasket, and the circlips (2). Also grab a chain while your in there. Total should be right around 200 bucks. You're also gonna need a flywheel puller ($15).

The cylinder wall is plated, so it dosent ever need to be honed real good. You do have to run a fine grit ball hone down there 3 or 4 times to remove the crap thats built up on the wall over the years, which will allow your new rings to seat. If you dont wanna buy a ball hone ($50) for a one time use, you could bring it to your dealer, there service guys oughta be able to do it pretty cheap.

[tai450f]

hey i just got a 03 yz450f and i love it, big jump from a 95 wr200( 2 stroke ) and i was just wondering if anyone els really rides many trails on em?

does anyone know of any good sticker kits out for them?

[TIG88]

I ride trails exclusively with mine, I'll post a pic of mine later this afternoon, I'm putting on the graphics kit shortly, from FLU designs.

[finthat]

For clutching while shifting, it is done either way. Depends on what I'm doing if I'm just trail riding I'll clutch 90% of the time, on the track I will go with out here and there more like 50-50 depending on the situation....eg. holding on for dear life = no time for clutch. If u do a search on here you'll find info about clutching. I would do the top end as well, along with all fluids including fork oil.

Have fun!

[GENE426]

I loved my 04 and never did anything to it engine wise

[TIG88]

Had to stop for Easter Dinner, its all done except for the tank graphics. It was a complete kit for 100 bucks shipped. I couldnt be happier.

[tai450f]

heyy thanks all, TIG88 your bike looks great, ill try to get some pics up soon, i like tha kit you have on it, im looking at something around the same, im only 18 so i more want to look at dc srh or anyother freestyle kits i can find if thers any out ther.

had my 2nd run on it 2day and its perfect! some times i dont think it even needs a front wheel, its had a full top end done just befor i got it ?

[XR133]

I recently picked up an '03 450 and I was really concerned that it wouldn't be a great choice for woods riding, but after getting it together and racing a couple of harescrambles on it, including one this weekend in OH that was as sloppy as they get, I find it to be a very capable woods bike. I'm coming from an XR400, which is about as forgiving as it gets, but this thing has all the low-end grunt and infinitely more top end. With a new S12 rear tire, I had no problems with uncontrollable wheel spin even in the soupy stuff. I did manage to loop it out on a hillclimb once, but that was operator error, not the bike's fault. ? Still getting used to the 4-speed gearing, but it's not a problem - just different. I think you'll like it...

[TIG88]

heyy thanks all, TIG88 your bike looks great, ill try to get some pics up soon, i like tha kit you have on it, im looking at something around the same, im only 18 so i more want to look at dc srh or anyother freestyle kits i can find if thers any out ther.

had my 2nd run on it 2day and its perfect! some times i dont think it even needs a front wheel, its had a full top end done just befor i got it?

What does age have to do with it? Im only 20 ?

XR133, you'll find that if you do alot of real tight woods stuff, that a 13 tooth front sprocket works really well. I dont have one yet, but I hear a flywheel weight is also pretty nice.

Ive also found that in the woods, at least without the flywheel weight, it helps to keep the idle a little high.

I'll post a pic when the tank graphics are on. Its a pretty sweet kit.