Airbox leaking ...?? 07 FSR need help

[Why Z?]

Hey all,

I think I have a leak in my air boot that is causing a lean surge and other lean related issues and possibly gotten some crap in the motor so I am now trying to fix before I ride my baby again.
See it you think I am right and if so, what I can to to remedy the problem:

Some background on the bike :

I picked up a 07 EC450 FSR. (Fuel injected 4t)
Basically brand new (was a research bike for a major power sports company and then it blew up and I bought it from a guy who was a tech for them and bought it and rebuilt it)

Anyway, long story short bike is basically brand new when I got it (20 km) and now it has close to 300km so still pretty new.

Shortly after I got I noticed some funny things :

-hard starting when cold (very finicky sometimes refused)
-backfired quite a bit but I didn't think too much of it as a lot of 4t do this
-would occasionally stall on decel after cruising speed and letting off the throttle
-seemed to run a bit hotter than it should have but I nothing extreme
-started bogging between stopped and first, 1st and 2nd
-started hesitating/surgin at cruising speeds (on road) without moving throttle. Not extreme but not right either . Ran kinda jerky like

-IDLED FINE. Not high or low just fine
-gas: 91, non-ethanol pump gas

I started to consider the possibility of an air leK. I have hated how this filter/airbox works from the first place - it's so tight in their it is hard to even get your hands in there to feel for a good seal - let alone see it. Still, I was careful with this.

Despite my effort I think air getting in some where.
On the airboot where the "gasket/lip" part of it braces up against the air box face (on the side in front of air filter) it doesn't look sealed.

I TAPED THIS PART UP w electrical tape, and the "surging/choppiness" went away, seemed to start/warm up better, seemed to run WAY smoother at speed.

Then the tape on the filter started to fail (just a short term fix) and I noticed some noise coming from that area that sounded like a leak .

So I think I have a leak. But as I look at the design of the air boot it doesn't look like this should be possible. It is one piece on to the air filter,.... So....?

Does my diagnosis sound right?
What should I do to fix it?

-do I need to buy a new air boot?
-is there a way to seal the airboot/gasket etc or repair?
-are there any crossover options from other bikes so I can have a "normal" air filter/gasket/easier seal/wing nut? (Never had trouble on my previous YZf or KX bikes)

Sorry long post.
Thanks,
Katrina

[Jakobi]

Hi Katrina,

Sorry for the bumsteer in your other thread. I assumed the 2007 model 4T would use the same design airboot as the 2T for that year. After checking the parts fiche it appears I was wrong and what you are saying about the airboot sealing against the airbox is correct, and also appears to be a poor design at best.

The 2T models use part BE250128017
The 4T uses BFS450728017

Both share the same airbox face BE250728054. I've got a mate with an 09 450 so might be able to have a look at his. Same part as your 07 but not sure when I'll get a chance. Not sure if you can use a 2T boot on the 4T either. As for the gasket/mating surface it doesn't look like there is one. I'd be using some sort of gasket sealant though if it simply bolts against the airbox front.

The spring loaded retainer is gold. Better than any wing nut setup.

Hope that helps
Jake

[Jakobi]

PS. Can you have a look and see if the air boot bolts onto the airbox, or if it pushes through.

Exploded views etc and part numbers can be found here - http://www.gasgasmotos.es/en/manuals/models-2-2007.html

[Why Z?]

Thanks Jake,

The air box just pushes through.
Which is a weird concept for me to understand .

So after taking this thing apart just down to where I can see both sides of the air boot, I feel as if there is no where the air boot could possibly leak. There are no visible tears on the inside of the boot. It looks like smooth, pretty hard plastic, and it is continuous with the surface the filter mates against.

Even if there is space between the air boot and the air box (where that side of it pushes up against) that would just be air from the outside going around to the other side, correct? Because everywhere the air boot touches the air box is sort of the "exterior" of he air box is it not?
Basically what I am thinking now is the air box is more or less just "holding" the airboot into place.

And yes I looked at the parts diagram and that is how mine is I guess. IMO, not a super helpful diagram.

Now I am wondering if I just "made up" this leak because it seems physically impossible ... Unless, that air boot is 2 pieces inside somewhere where I can't see.

This is making my head hurt.

I really really love this bike but I gotta figure out how to make this air box sealed andor really understand that I'm worrying bout the wrong thing

Any ideas guys

[Logan]

Best way to find out if and where you have a air leak is to use starting fluid.
Start your bike let it idle, raise the idle screw if you need to too. Start spraying small squirts around the intake boot, carb and airbox. If the idle goes up you know you have a leak. Remember, small short squirts starter fluid is highly flammable and your engine will be hot.

Hopes this helps