HELP!! stock '04 YZ450F ???'s

Hey TTer's I'm looking for all of your knowledge and input. I just picked up a slightly used '04 YZ450 and would like to do all the cheap/free mods that will make the bike more user friendly, powerful, sexy..... whatever...?

Like I said it's stock.......Do you have to do a wire mod to them, possibly a BK mod....?? Give me a rundown or a list of neat mods or tricks that you would recommend!!

thanks in advance!! :cry:


What type of issues are you trying to fix? If it's too powerful you can either pull the TPS (do a search) or put on a 15t front. Other than that I dont know what else your looking for.

Just trying to figure out if there are any mods or upgrades that can/should be done to the '04. I did the BK mod to my 426,the wire mod, and a powernow.....

Like I said, just curious if the '04 needs any tweeking.... I want all the FREE horsepower or handling ability, or whatever that I can get......EVEN if I can't use it!! Meaning I don't have the riding capability to use it to the MAX!!



Your 450 does "NOT" need BK mod - don't waste your time - get a new chain - stock is junk and decent handlebars and go ride the beast. JD Jet kit will wake up the throttle....get a adjustable air screw - nice addition

I looked at the carb briefly but suspected that Yamaha had corrected the accelerator pump issue after the first couple of years but according to you....I guess not. I will look into the BK mod. I Have a set of Renthal bars that I'm putting on it and I will deal with the chain in due time.....

I definately will do a air/fuel mixture screw.....makes it really easy to make little adjustments when needed.....

What does the JD jet kit do/provide.......??? I have several jets from all the bikes I've had in the past and have just winged it on the jetting issues based on the tailpipe color and plug color... I'm willing to listen to anything that may improve the...already awesome...YZ450F!!



I read his post above several times yesterday and the wording doesn't make a lot of sense. I think he left out the word 'not' in it.

"Your YZ does NOT need the bk mod - don't waste your time."

That looks like what he meant to say.

My YZ hasn't given me any indication that it needs the mod. With a few jetting changes it runs perfectly.

my 04 has an applied top clamp,protapers & 756dunlops(yes they wear out fast but they work best for me)this thing ripps!

overrdrive-a 13 tooth front sprocket?for the woods i guess? mine has stock gearing-ripps holeshots in b class mx all the time :cry:

SO........It does NOT need the BK mod??? I haven't even put a lap on the track with this bike. I did ride it for a short rip in a field near where I purchased it and it really pulled hard......even compared to my 426 that I have set up just right for me!! I do think the guy had VP race fuel in it though :cry: which is supposed to make a ton of difference in performance.

I'm not going to get too excited about changing gearing just yet. I'm a fast "C" rider or should I say a SLOW "B" racer... I think the stock gearing will work for now. BTW, I'm 6'4" and 230 lbs with gear on...... I'm going to put handlebar adapters on the stock triple clamps so that I can put on the TAG bars that I like.

Any other things that you can think of that will help for tall guys.........I'm all ears...



Try picking up some lowboy pegs. I am 6'3" and the extra 1/2" back and down helped huge on my YZ250. Also when you get more money try picking up some triple clamps that push the bars away from you. It makes standing easier...more room for the tall guys.

overrdrive-a 13 tooth front sprocket?for the woods i guess? mine has stock gearing-ripps holeshots in b class mx all the time :cry:

It's just a playbike. I've never even been on a track before. I just wanted a fast bike with a ton of power. The 13T is to lower my first gear so I can putt along better when I want to. I've only had it in 4th gear two or three times so I didn't miss the top end...

I spend most of my time riding practicing wheelies. The 13t was a definite plus for me. :cry:

I might just leave it as is and go ride it first. You might like it stock.

I guess I can live with it the way it was built..... sounds like it must be pretty good based on all the lookers and very little input on inprovemnets.....I just dropped off the suspension at MX-tech to have him go through it and set it up for me..........big guys that ride poorly... :cry: so we'll see.......

thanks for all your input


if your looking for a free mod that makes your bike look better i suggest the pipe mod. I've done it to my bike and cant tell any performance difference but it definately looks a lot better. Cut a few inches off the tail pipe. I cut 4 off mine and i think 5 woulda been perfect. if you look back theres a few posts about it.

Dont do the BK mod! It is not necessary. I wouldnt cut the pipe down either, it is designed for a smooth powerband. If you cut it down in length it will change the characteristics of power, maybe better at the top but sacrificing the bottom. Ride the bike and see what it lacks if anything. There is enough for the pro's I would think that would be good enough for me at least til I rode it for awhile. Getting your suspension set up for you was your best investment. The JD kit has special custom needles that have been developed for your model. I have read nothing but good about his kits. :cry:

Once again, Thanks for the ideas...... I did get a set of fastway pegs to lower them down. Feels better already even if it only drops my stance a 1/2"!!!

What kind of price can I expect to pay for a JD kit, and where do I find them?? I'm going to go and see if I can find an adjustable air mixture screw, I had one on the 426 and was really handy for making the adjustments needed.


TT Shop sells the JD kit for $69....they advertise it on the home page. Let me know if they make a difference. I've been considering a set. :cry:

Scrap the stock chain for a solid OEM one and replace the case saver with a plastic unit from Zip ty racing. You'll probably save yourself alot of money in the end by taking care of this business first.

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