WR250R Modifications

Hi everyone, i just recently picked up a 2008 Yamaha WR250R and had a few questions about some things the previous owner did to it. I'm new to these fuel injected bikes and all the different sensor inputs and emissions controls. First I'll list some of the mods already done. It has a FMF Powercore 4 slip on muffler with the stock header, flatland racing skidplate, cargo rack and hand guards along with pro taper bars. I was going over the bike thoroughly after getting it home and noticed two cable ends that had been cut close to the muffler, after doing some research i found that the cable is connected to a servo that operates a valve in the exhaust pipe. The previous owner cut the cables and left everything else intact and plugged in.. Is there some kind of delete item i need to install to correct this? Also i've read that with an aftermarket pipe it's recommended to get the power programmer is this true? Also does this bike have any kind of oxygen sensor? I looked all around the pipe and in the wires bundles for a pigtail but couldn't find anything. I was hoping to keep the bike stock but i guess that won't happen now. Other then the butterfly in the exhaust being gone i believe the rest of the emission control are still intact. IE the flapper in the air box and the Air injection pump. I've also noticed it has a slight hesitation when accelerating is this do to some of the mods?

Howdy.

Personally, I think the guy was a dumbass for cutting the cables instead of using tools and removing them from the electric servo motor that controls their movement.
You can either remove what's left of the cables and leave the servo motor plugged in, or remove both the cable remains and servo motor and install a "servo eliminator" device (like the one sold by Graves Motorsports) that fools the bike into thinking the servo motor is still there.
Myself, I'd just remove what's left of the cables and leave the servo motor plugged in.

It's not absolutely necessary, but the bike will run better and have better throttle response if you add a Power Commander, FMF Power Programmer, or other fuel programmer.
I rode my 2008 WR250R back-to-back both with and then without my programmer hooked up, and I couldn't wait to get it hooked back up.

USA bikes don't have an oxygen sensor.
Euro bikes do.

Yes, your hesitation could be due to the bike wishing it had a programmer installed.
I'd also make sure the fuel in the tank is 100% fresh (not trusting what was in there when you bought it) and service the air filter.

YZEtc wrote:

Howdy.

Personally, I think the guy was a dumbass for cutting the cables instead of using tools and removing them from the electric servo motor that controls their movement.
You can either remove what's left of the cables and leave the servo motor plugged in, or remove both the cable remains and servo motor and install a "servo eliminator" device (like the one sold by Graves Motorsports) that fools the bike into thinking the servo motor is still there.
Myself, I'd just remove what's left of the cables and leave the servo motor plugged in.

It's not absolutely necessary, but the bike will run better and have better throttle response if you add a Power Commander, FMF Power Programmer, or other fuel programmer.
I rode my 2008 WR250R back-to-back both with and then without my programmer hooked up, and I couldn't wait to get it hooked back up.

USA bikes don't have an oxygen sensor.
Euro bikes do.

Yes, your hesitation could be due to the bike wishing it had a programmer installed.
I'd also make sure the fuel in the tank is 100% fresh (not trusting what was in there when you bought it) and service the air filter.

Thank you for the response! I was reading up on the forums here and found a way to make a delete for the exhaust servo by using a certain resistor, do you know anything about this and how well it works or should i buy the one from graves motorsports? And i have to agree the previous owner was a idiot for cutting the cables... So now the whole thing is junk. But i'll definitely look into a fuel programmer I've heard they work wonders on these bikes.And even with the bit of hesitation the bike still feels pretty fast so i'm interested to see how much more it will gain. And you may be correct about the fuel, the guy i bought it from said it hadn't run in a few weeks so i'm assuming the gas is a bit old. I'll get some 93 octane for it tomorrow and see if it helps any.

First, welcome and congrats on your new ride.  


Either buy the servo eliminator or make one yourself (resistor mod). I bought mine. You know it'll work.

Programmer will help with the hesitation and add responsiveness. Install one.

If you are going to add the programmer, you might as well change your air filter for something that can breathe better. Generally, NoToil for offroad, K&N for street.

Gas. A few weeks old? Just burn it (run the bike) and add fresh 91 when needed. I leave my bike sitting in my garage for 5 months during winter with a full tank of 91 and it starts and runs fine in the spring. No worries.

Don't be afraid to mod this bike, stock is nice and all for...(Sorry, I really don't know why anyone would keep it stock). It wants to be modded and abused. This is a rock solid bike, it can take a beating, all day long, day after day.

Read up on all the engine/emission mods on here, and then do them all. Gear the bike down a bit, and you will have a fun little motorcycle.

Enjoy!

Gearbox94 wrote:

YZEtc wrote:

Howdy.

Personally, I think the guy was a dumbass for cutting the cables instead of using tools and removing them from the electric servo motor that controls their movement.
You can either remove what's left of the cables and leave the servo motor plugged in, or remove both the cable remains and servo motor and install a "servo eliminator" device (like the one sold by Graves Motorsports) that fools the bike into thinking the servo motor is still there.
Myself, I'd just remove what's left of the cables and leave the servo motor plugged in.

It's not absolutely necessary, but the bike will run better and have better throttle response if you add a Power Commander, FMF Power Programmer, or other fuel programmer.
I rode my 2008 WR250R back-to-back both with and then without my programmer hooked up, and I couldn't wait to get it hooked back up.

USA bikes don't have an oxygen sensor.
Euro bikes do.

Yes, your hesitation could be due to the bike wishing it had a programmer installed.
I'd also make sure the fuel in the tank is 100% fresh (not trusting what was in there when you bought it) and service the air filter.

Thank you for the response! I was reading up on the forums here and found a way to make a delete for the exhaust servo by using a certain resistor, do you know anything about this and how well it works or should i buy the one from graves motorsports? And i have to agree the previous owner was a idiot for cutting the cables... So now the whole thing is junk. But i'll definitely look into a fuel programmer I've heard they work wonders on these bikes.And even with the bit of hesitation the bike still feels pretty fast so i'm interested to see how much more it will gain. And you may be correct about the fuel, the guy i bought it from said it hadn't run in a few weeks so i'm assuming the gas is a bit old. I'll get some 93 octane for it tomorrow and see if it helps any.

New member here, first post. I would suggest doing the resistor mod. Go to radio shack (before they close them) and get a 10k-ohm 1/4 watt resistor. Look at the picture at the bottom of this page and do the same. http://www.thumpertalk.com/topic/699479-cheapest-diy-servo-bypass/page-4. Wrap w/electrical tape. Simple, cheap, and effective. Did the same a few weeks ago on my new (to me) wr250r.