new 07 wr250f

[trailfox]

I just bought a new leftover 07 wr250f, I have done the free mods.(exhaust baffle removal,grey wire and the yz throttle stop is on order. I have also removed the air box baffle and lid.) I have a bad bog if you wrap on the throttle to hard. I've read about rejetting. I've also seen powernow systems and demissions powerback kits from F2 racing. I was needing help on the best fix for the bog.any info would be greatly appreciated.I'm also new to thumpertalk and new to trail riding so i don't know much about tweeking on this bike yet. thanks again.

[William1]

Read all about the O-Ring Mod and AP Tuning

Do not do the powernow or any similar gimmick.

Get a James Dean Jet kit, get a Merge Racing extended fuel screw. Both from the TT store.

[trailfox]

thanks for the info. I will check it out. Does the powernow now system not work.

[WR250F Captain]

the powernow system costs more than the F2 racing bulls eys and its half the product.

it's not dyno proven, just word of mouth

that bog when you wack the throttle is from the accelerator pump not being timed right.

[lincoln224]

I have a 07 wr too. You WILL need to re-jet, along w/ the o-ring mod. It should get rid of that bog. Do not buy the powernow. I did, and it made my jetting problems worse. Took it out, and not my bike is running good. I also went up two teeth on the back sprocket, but I needed more low end for riding in Colorado.

[trailfox]

Is there any rule of thumb for determining what jet size to get ? Does it help much to remove the emissions pump ? Thanks again for all the help and info.

[Hilo Thumper]

Is there any rule of thumb for determining what jet size to get ? Does it help much to remove the emissions pump ? Thanks again for all the help and info.

Check the Jetting Data Sticky at the top of this forum for a bike that's used under similar conditions as yours i.e. altitude and temps and use that as a starting point.

Most Jetting Kits (F2, DJ, James Dean, etc.) have a recommended jetting included in the instructions and are usually pretty good start point as well.

Congratulations! ?

[trailfox]

thank you

[trailfox]

what is the AIS? Is that the emissions box on the frame?

[WR250F Captain]

what is the AIS? Is that the emissions box on the frame?

AIS is air induction system, that pumps fresh air into your exhaust and is vacuum operated. its what makes it go pop pop pop when you engine brake.

if your talking about that bronze pump thing that, on mine atleast it did, says mikuni on it then yes

but correct me if I am wrong:bonk:

[trailfox]

is that what everyone takes off and replaces with the demissions kit?

[WR250F Captain]

is that what everyone takes off and replaces with the demissions kit?

YES it is ?

[trailfox]

What is the taffy mod on the cfr carburetors ? I believe that is what is on mine. Is the crf-mx carbs on the yz bikes only ?

[WR250F Captain]

What is the taffy mod on the cfr carburetors ? I believe that is what is on mine. Is the crf-mx carbs on the yz bikes only ?

why would you put a CRF carb on a YZF?

never heard of a taffy mod.

your not getting FCR confused with CRF are you, cause my KTM has a FCR on it as well

[trailfox]

yea, my bad. I meant FCR. I was told to do the o-ring mod to help eliminate the low idle bog. i read that the o-ring mod is for the FCR-mx only and that the taffy mod is for the standard FCR carbs.

[WR250F Captain]

yea, my bad. I meant FCR. I was told to do the o-ring mod to help eliminate the low idle bog. i read that the o-ring mod is for the FCR-mx only and that the taffy mod is for the standard FCR carbs.

I believe the WR only has a FCR, not the FCR MX. I've never heard of the taffy mod, but do the o ring mod.

whats this "taffy mod" you speak of?