just got a used wrx, wondering about some existing mods?

I just bought a 2008 wrx. The bike has the baffle removed, and the air box mod. (flapper mod I believe) and possibly the ais removed. 4500 miles

Unfortunate I didn't research the mods beforehand and after reading around I am worried the bike may be running lean. It seams to be running strong to me, but i don't have much to compare it to.

Just looking for advice on what to do. Should I be worried about the air/fuel mix and buy a programmer? Or maybe the damage has allready been done? I understand this bike runs lean from the factory, but am not sure how much mods affect the bike?

handyman439 wrote:

I just bought a 2008 wrx. The bike has the baffle removed, and the air box mod. (flapper mod I believe) and possibly the ais removed. 4500 miles

Unfortunate I didn't research the mods beforehand and after reading around I am worried the bike may be running lean. It seams to be running strong to me, but i don't have much to compare it to.

Just looking for advice on what to do. Should I be worried about the air/fuel mix and buy a programmer? Or maybe the damage has allready been done? I understand this bike runs lean from the factory, but am not sure how much mods affect the bike?

When you say "baffle" are you referring to the spark arrester and the little end cap?
Or are you talking about the EXUP valve that's inside the pipe?

Is the majority of the stock exhaust system still on the bike? Most of the muffler?

If so, I think you'll be okay.


If you keep the bike for any extended period of time you'll probably want the programmer and a pipe and some other goodies too. It's an addiction.

Most of the exhaust is still on the bike, I believe that only the spark arrester and end cap were removed.

A quick look at the exhaust header pipe right where it comes out of the cylinder will tell you if the AIS is there or not.

A quick look under the seat at the "snorkle" on top of the airbox will tell you about possible flapper mod.

Based on what you've stated - I don't think you're in danger of hurting bike by being too lean.

If you're really concerned you can probably find a spark arrester and end cap on eBay or even here at this forum.

A guy is parting out his bike in the "for sale" section.

Thanks, I feel much better now.

I also ordered a uni filter fit it, am I correct in assuming there is now way it could affect the engine enough to do any harm?

handyman439 wrote:

Thanks, I feel much better now.

I also ordered a uni filter fit it, am I correct in assuming there is now way it could affect the engine enough to do any harm?

Not sure about your last sentence.

If you open up airbox enough, and open up exhaust enough, you do run into the danger of getting too lean.

At least that's the "most posted theory" we all seem to live by.

I'm a member here, at ADVrider, supermotojunkie, and thumpertalk. I've not seen any posts about somebody getting so lean their bike was damaged. Most people don't want to push that envelope.

If you alter the intake and exhaust you need to really consider getting a fuel programmer to increase your fuel ratio to prevent going too lean.

I don't think just the flapper mod and removing the spark arrester is enough to be dangerous in terms of leaness.
If you were to remove airbox door completely, or start drilling holes into airbox I'd recommend you get a fuel programmer.

If you remove stock exhaust and replace with a more open exhaust pipe, I'd recommend you get the programmer.

A few hundred bucks for a programmer is way cheaper than fixing a damaged engine.

From what you've posted though, I don't think you should worry about being too lean for now.

However - I can't see you bike, or know what's been done....and internet advice is not always the best advice to bank on.

Maybe some others here can chime in and confirm or debate what I've posted.

It's best to never take one persons word for anything on the internet.

What I ment was

- I am changing the origional filter with an aftermarket "uni" brand filter.

One more area that could possibly lean the bike out a little more.

I know the K&N air filter supposedly lets way more air into system than the stock filter.

Not sure about the UNI brand you're referring to.

Since your exhaust is still mostly stock, which means it's still plugged up pretty good, assuming the pipe hasn't been cut open, gutted, and rewelded, you're probably still safe to run without fear of being too lean.

well, I finally had time to work on the bike a bit. Turns out the entire flapper assembly was removed, leaving a big hole in the top of the air box. Now I am worried that this thing has been running too lean again?

Picture of my spark plugs, new and old

Just did a compression test on the bike. Only 90 psi warm or cold. Took at least 10-12 cranks to get there.

I dont know what I am going to do now.

handyman439 wrote:

Just did a compression test on the bike. Only 90 psi warm or cold. Took at least 10-12 cranks to get there.

I dont know what I am going to do now.

What's it supposed to be? I have no idea what the compression should be in terms of psi.

Why are you doing that check?

Does the bike run strong?

Are you sure you're not bumming yourself out (obsessing) over stuff you might not need to be worried about?

I called a couple dealers to ask about the airbox, they said they would not recommend opening it up like that.

According to them, normal is 110 or 120 to 150 or 155.

The bike starts good and seams to run fine. This is my first dirt bike so I have nothing to compare it to. Good chance I am over reacting, but i am pretty sure it's not running 100% anymore.

Just searched through the .pdf service manual available somewhere on here.

Per the manual compression should be 105 (min) - 135 (max) psi. Standard is 121 psi.

Keep in mind, guages vary. No two guages read the same. Low compression could be a result of a poor ring seal, or poor valve seals.

I don't think the plug looks too bad; maybe a bit on the lean side.

handyman439 wrote:

Just did a compression test on the bike. Only 90 psi warm or cold. Took at least 10-12 cranks to get there.

I dont know what I am going to do now.

Did you check with the throttle WFO?

handyman439 wrote:

I dont know what I am going to do now.

Get the 280 kit from Thumper Racing and call it a day! (this is assuming the rings are the issue)

I think people are over-reacting here.

We went from "do I need a fuel programmer?"

to

"you might need a whole new top end"

Before jumping to hideous conclusions I think people should go back to basics and work forward.


Slowly.

Can the OP tell us where he lives? Maybe somebody here at this forum lives near, and can assist in a hands-on way to see what's going on?


Worst case scenario I think the OP should take bike to a Yamaha dealer and have it checked over.

I live in minot nd.

I did the compression test with the throttle at idle, as instructed by the local yamaha dealer.

I actually went in and talked to their mechanic about my issue to see of he could look it over. The guy didn't seem like he wanted my business. Acted like a prick the whole time and finally said "maybe I could take a look, but it will be at least 3 or 4 weeks, if your lucky"

handyman439 wrote:

I live in minot nd.

I did the compression test with the throttle at idle, as instructed by the local yamaha dealer.

I actually went in and talked to their mechanic about my issue to see of he could look it over. The guy didn't seem like he wanted my business. Acted like a prick the whole time and finally said "maybe I could take a look, but it will be at least 3 or 4 weeks, if your lucky"

If you check compression with the throttle closed you are restricting the intake air, this will give you a false reading.

Twist the throttle wide open and see what you get for a reading.

I will try this tonight if I have time. I also plan on testing my gauge against another to see if it may be inaccurate.

Why do you think it's lean? The mods you stated will not make it lean. Just ride it. Remember it's a 25 hp bike.

OK,

I guess I am overreacting. Got an expensive toy and wanted everything to be perfect?


I did the compression test again, WFO, and got 110psi, which may be towards the lower end, but nothing to worry about I dont think. I also realized that there is something extra on top of the airbox. Anyone know what this is, or where it came from?

That's the tip-over (AKA lean angle) sensor.
If the bike tips over, it is supposed to do something like cut ignition, cut fuel, etc.

If that were my bike, I'd install a fuel programmer because it gives better throttle response.

Is the lean angle sensor actually mounted in that picture? In that picture it is aligned such that it would be a wheelie/stoppie sensor. The long dimension of the sensor is normally aligned such that it runs from one side of the bike to the other, not front to back. First picture in this thread shows how they are normally mounted from the factory.

Ya, that how it is currently mounted. I will probably move it to the stock location.

I am thinking about getting a fuel programmer for peace of mind if nothing else. I havent researched them much, but it seams like most people run the FMF. Should I look into other options or is the FMF the way to go?