jetting?

[maddmatt02]

I got a 04 YFZ coming, I get the money on the 22nd of this month to buy it and then it gets put onto a truck and on its way. its jetted to run at sea level. were at 5k or something, plus right when I get it I am going to do the cam mod, and ditch the pro design kit and get the FCI intake kit. so I am going to need to jet it, and since I havent really even finished getting my 300 set, I dont really wanna spend time learning on an expensive bike, so I was just gonna see about bringing it in to get it on the dyno? whats the hourly fee? also how long is setup, can you usually get it setup and jetted within an hour?

also, about the oil mod, Ive seen on YFZcentral a guy did it by drill/tapping for a jet, making a groove for the oring, and using the original oil pump. I think he said he still has around 40psi of oil pressure.

do you think that that is sufficient or do you have to get the new pump? and is it reccomended to buy the more expensive kit using oem parts?

[rollercoasterdan]

First off, look around here http://www.yfzcentral.com/invision/ There is a TON of great info. 3rd, save up some money and do this oil mod, http://www.jtatv.com/yfz450-oil-upgrade-kit.htm Best for the money unless you need a new side case already.

About the jetting, I have a non cam-modded 04 with a full GYTR pipe and a Pro Design filter and I have a 165 main and a 45 pilot, not too sure about the clip position/screw. Something around there should work out just fine. But before you go changing things just try running it, the jetting may be fine already.

BOG: Replacing the stock leak jet with a #35 leak jet is supposed to help, look on yfzcentral for more on that. Otherwise they have a few mods. If it is jetted perfect there will be little to no bog.

Post up whats its jetted with after you try it out.

Anyways, be careful at first with 450, big step from a 300 to a 450. Dont worry about buying an FCI yet, you'll already have more power than you know what to do with (assuming the DRD in the sig means a Dr. D pipe)

And lastly, much better choice going YAMAHA

[maddmatt02]

yeah, I hear people say dr. d but isnt it really dubach racing developmetn or something? also, I have ridden it plenty before, I am fine with the power, bike I raced with was a big bore stroker, cam'd, 460ex. in a drag the yfz would barely beat me though, and wasnt rider because we did double passes back to back and all 4 times were same exact results. I got a 39mm FCR on the 460 but never got it tuned before the bike left, but from the early stage I knew id walk the 450 after that.

also I ride a crf250 alot, have owned a R1 and a daytona 600 so I am used to having a good amount of power under me.

and about the jetting, I think its in the mid 170's and i dont know about the pilot, but they ran 50/50 91/104 most of the time and jetted it for about 100 feet above sea level because it mostly was only ridden at winchester bay, OR. I cant wait to get it out to glamis or dumont now that its gonna be down here.

and I have nothing against yamaha but only reason its a yamaha is because I got it with sand/stock/FT tires/wheels, piped jetted, graphics, lowering kit, pro design, nerfs, bumper, all stock parts and I know its entire history, for 2600. I was dead set on getting a 450r, and I bet I still will and give this to my girlfriend eventually. I havent touched the 300 in a while, one reason is it doesnt charge, but the reason I dont fix that is when it is running the power just doesnt impress me at all. I have to punch it up and drop in a cam, etc... before Id consider it fun, Ive ridden a built 330 and it was actually an awesome bike, no 450, but really fun.

[maddmatt02]

you'll already have more power than you know what to do with

oh also, forgot to add, theres no such thing as enough power. your talking to the guy who bored/stroked/ported his pocketbike and has the race pipe on it and all.

[rollercoasterdan]

oh, I thought you had only ridden the 300. Those jets he has in there are probably going to put you way too rich. But with a fci you never know. Anyways good luck, might see you at sw sometime.
Running 91 in the motor is fine as long as he didn't bump the compression up then you might need to run mix

[maddmatt02]

nope, engines never even had an outer case cover off at all, except for a warrant repair of a waterpump problem, I cant remember what it was, but it was leaking and I dont think it was just a gasket. but other than that no internal repair/modification.

I was thinking about cams, but went over a dyno comparison and none made more power before 8k and barely made more after, and quite a few lost power all the way around.

so Im not doing that, and I doubt id bump the cr for the small gain.

[ElderGeek]

Dan posted the oil mod link.

Here is an earlier discussion we had.

Here are a few more links for your YFZ.

DogDad Tech pages, a little old but still applies.

Step by step cam mod

Yamaha parts catalogue

Yamaha SERVICE Manual


Enjoy your new toy!

[maddmatt02]

oh man I cant believe Im gonna own a yamaha. now I get to hear all the crap about hondas from true yamaha fans and they are gonna think Im just like them and hate honda as well...

[rollercoasterdan]

Don't worry, you'll never go back to Honda after this anyways
But to make it more race ready if you want to, you can usually find a pair of std. travel +2 a arms for $300-$400 and an extended axle right around $200 on yfzcentral.

Right there you would have a decently MX/Dune ready quad that has a a lot of power too.

[maddmatt02]

I was looking at having GT thunder revalve/respring front and rear and long travel real link, and some +2 SMC arms, I thin they are 475 with lifetime warranty. maybe some JD arms. I might not wanna put too much money into it because I can GAURANTEE I will go to a trx450r eventually and give the yfz back to my girlfriend. even if I know the yamaha is a little faster stock, for some reason I just always have liked hondas.

and yeah i have ridden a 450r, it was ALL stock though. but it was still pretty impressive for being corked up.

I do have to say I like the characteristics of the engine in the yfz alot more, but the honda was all stock so who knows what it feels like once its piped and properly jetted.

it has 3" rear wheel spacers right now, and although its not the best solution, it has been jumped quite a bit, raced a bit, bumped wheels all the time and they are still holding up fine. probably just leave it like that til I bend the stock axle from the extra leverage or something.

I cant wait to get this thing down to mexico this christmas. fastest thing ive gotten to fly down the beach on down there are 250ex's. so Ill be able to go about twice as fast down the beach now.