I am wondering what the best and easiest way to gain power out of my baby F would be?

It all boils down to power to weight ratio. reduce weight vs increase power. The best (and cheapest) place to loose a lot weight is the rider. (assuming you are normal and not already at 5-7% fat and buff) But that can also be the most difficult. With 4 strokes the best way to gain power is displacement, but that usually comes at the cost of reliability. If you already know all these generalities, I apologize.

The 250F is in a fairly high state of tune as delivered. A pipe will gain a couple of HP usually at the cost of more noise. Or just moving the power around. Gearing will change the power delivery but not actually change the hp numbers.

Carburation is about as good as possible without going to a fuel injection (which does not exist, yet). Probably the best possible way is a big bore kit. Old timers have been forever saying with regard to 4-strokes....."there is no replacement for displacement".

As for myself....I think my stock YZ goes pretty good. I am also at 200 pounds without gear. In the day when at a "fighting" weight of 165 pounds I really rode well. I am currently loosing that 35 extra pounds. I am confident my YZ will down right rip when back to 165.

search TT for previous discussions on big bore kits.

You don't say what if any mods you've already done to it so to increase the power:
Add a pipe of your choice and re-jet to match
Get a Power Now intake bell to help the low end pull and make for easier starting
Get a Boyesen water pump cover and impeller. The combination of the two reduces parasitic drag and the improved impeller design helps the bike run cooler. Cooloer motor = more power. Factory bikes always have modified covers/impellers for that little extra.
Snap up a Vortex ignition module and replace the stocker. It has better power everywhere.
After these mods examine your gearing for the riding you're planning to do and adjust a tooth or two to maximize your punch.
Keep in mind if you're racing that a suspension calibrated for your weight and riding style is worth more than some extra HP.

Besides the impeller and cover for easy. I would say run an oxygenated race fuel and jet properly. The jetting should be done anyway regardless of fuel. After that some of the stuff starts to get a little less easy.
PK

I was told that race gas isn't good for an engine that has nothing done to it, ex. like after market stuff. My bike is jetted perfect right now, the suspension is in getting done right now.

1. Get a 450
or
2. Twist the throttle more
or
3. Learn to ride faster
or
4. Buys an exhaust system
or
5. Run a higher octane gas and speed up the timing. (Just guessing on that one )
or
6. Hook some nitras oxide up to it.

now for my first words i dont want to seem like a smart alick ( i think thats the spelling)
1. y do u want more horsepower... honeslty these bikes have enough power in them to make any person happy. i mean all of the bikes have so much horsepower that even RC cant use it.. no offense to racing.. and unless u are running in the big leagues with him then y worry.
2. yzracer... no.... upgrading a bike just to be able to twist the throttle a bit more and to ruin an engine with nitras oxide if u arent going for a speed record is a waste.. if anybody thinks about the bikes as they are... they are running grenades.. i mean y are dealing with explosions beneath your crotch every what second??? not a good thought *shudder* but really is the extra horse poewr needed.... if u want to go faster... go to the WR and take off the head light... get a YZ tank and seat... get a vortex ignition system an aftermarket pipe and hang on. My WR will top out around 90 and the YZ tops out at what 58 56.... all that the YZ has over the WR is weight ( which with the removal of a few things can be changed) and the acceleration... so just my thoughts...

When i said to hook up some nitro i was being a smart a**

vtcyclist-
"Carburation is about as good as possible without going to a fuel injection (which does not exist, yet)."

you might want to ask the Cannondale guys about that one. the Cannondale bikes ARE fueal injected.

Cannondale are fuel injected? Absolutely. I am aware. But we are speaking about Yamahas. No stock or aftermarket fuel injection is available for 250F.

I have done some research and came to the conclusion that I will buy a Vortex Ignition system, it looks like the easiest way to move the power around and add a little aswell. I have the YZ dude, not the WR. And after I refill the bank I will put a Big Gun on it.

Actually if you really want to spend the money, you can buy the same fuel injection used on the Cannondale bikes from Optimum Power Technology https://www.optimum-power.com
Prices start at $2500 for the 250F and go up to $3000 if you want the full package with map select options. It is a pretty cool idea but HOLY CROW is it expensive.

hey.. i didnt say that u had the WR i was stating what the differences between the bikes were in the means of horsepower and top speed... i dont know exactly y u want more power

I want more power because I don't want to move to the 450, I just want to squeeze my bike for all the power it has potential for.

If your racing the bike in the 125 class you can take it to 262 and still be legal. I run the Dubach pipe and am really pleases, heard good things about the Yosh pipe as well. The Vortex did wonders for the 01 but really cooled off on the 02's since Yammy remapped their ign. You'll want to do the free "Now" intake track. Don't forget the 03 E cam is a must!

that still doesnt say anything... if u dont want to move to the 450 then dont.... i guess that im still confused about y u want the power ..... and potential... it has alot... but what it has stock is still a whole lotta power

power bomb header;
power core 4, or white bros pipe;
softer tires your terrain allows;
lowest tire pressure you can get away with;
race fuel (and rejet for it);
bigger rear sprocket;
vortex ignition;
high-flow air filter.

hotcamsinc.com also sells a race cam, but you in fact already have a race cam in your bike, and there have been occasions when people have had bad results from trying to take these bikes hotter than they already are, fundamentals-wise.

joe

Carburation is about as good as possible without going to a fuel injection (which does not exist, yet).

I've read and seen pictures of fuel injection on a 250F in a Dutch mag. They were testing it in Veldhoven, The Netherlands. looks pretty interesting. I'll post some kind of translation of the article later. The guys that started this project are located in the U.S. though.

Later more....

GAS GAS has a new 400 fuel injected thumper.

i read an interesting report on fuel-injected dirt bikes just the other day. the headline on it was "cannondale files for Chapter 11 bankruptcy protection" ...

of course fuel injection is an intriguing idea. but whadda you do when you put a different pipe on it, or go to a hotter or cooler spark plug, or take it to denver where the air is less dense, or take it to Galveston, where the air is super dense and wet, or do any of the hundreds of mods we do all the time. each and every one of these would require a new ignition mapping to be downloaded into the logic circuit controlling the fuel injection system and ignition. sure, cannondale provided a handheld unit for doing just that, but what a load of crap to have to go through just to change jetting for cold weather.

if you look around yamaha's corporate site, they in fact have an in-house project going where they've retrofitted a fuel injection system onto some blue bikes. hopefully they'll keep it in the laboratory for a good long while :-)

joe