what mods should i make to it? and i heard changing the front sprocket helps anyone know what size that would be?

 

do you have a ltz400 or a ltr450?

 

Or a yfz as in the title. It irritates me when people put things in the title but don't restate in the subject. Anyway, ltzguy450 do the norm pipe, filter. Most will tell you do suspension upgrades first when racing.

 

Well you didn't say what kind of racing you were going to do. I don't know much about flat track racing but I know a little about setting up a bike for motocross.

If you expect to hang with anyone you'll have to do a high comp piston, 13:1, (Most won't let you change bore size so know the regs where you want to race) you'll have to use 110 racing fuel with the 13:1, different cams like hot cams or web cams (yeah it takes two) full exhaust, jet kit, K&N with a moded air box, and a major suspension overhaul. You'll need an extended axle, extended a-arms, (my local tracks have a max width of 51 inches again know the regs where you want to race) different front shocks (like Elkas, long travel is better) something triple rate where you can adjust preload, compression (the best shocks have low and high speed compression adjustability) and rebound make sure it's vavled for your weight, would recommend different rear shock (same applies to rear as the front shocks) but if you wanted to save money you could use the stock rear shock with different linkage (Elka makes a linkage kit you can use with the stock shock but gives you more travel)

If you can afford that and you have money left over then you'll want to cut your vavles, port and polish your head, and get a new steering stem and handlebars.

Take of your headlights, tail light, parking brake (get a block of plate for the rear caliper) and get different rims and tires like holeshots, they make different versions with different compounds and some grip and wear better than others. It'll take a few sets to determine which work best for the dirt you race on. Strip you stock stickers and get a cool graphics kit, or have someone sponsor you and use their stickers. Don't forget to plaster the stickers from all the aftermarket parts you just bought all over your bike. Get bumpers that you can attach numbers to and add a kill switch tether.

This should get you started and after doing all of this you will learn enough to start working out the details that will make your machine faster. After all of that start learning to ride from the other guys at the track that are beating you.

Oh I almost forgot I'm assuming you were talking about a YFZ 450 btw so I would drop a tooth on your front sprocket.

 

alright thanks and yea motorcross racing well this is my first year racing a full season and i think i racing stock class but i can change anything in shocks just cant touch motor or with of bike.
thanks and yea yfz450