Welcome back to the channel guys. My name is Cameron. And today we're gonna be tinkering on this beauty back here
it's a 2003 CR250 that I've been building and
Today we're gonna be discussing one of the biggest issues with these bikes and that is how the air boot seals to the airbox
A lot of you have probably heard of this. It's a really crappy design and
Could lead to a serious engine failure. So definitely worth looking into you
so the problem with this design is that all that seals the boot to the airbox is
This little foam gasket and that's definitely not enough
So when you tighten the screws that hold the boot on to the airbox the boot will actually warp
maybe not quite to that degree, but
it'll create a gap there and
That allows air and more importantly dirt to go through there and into the engine. This design was used on the o2
207 co2 50s, which I have here and also on the
2002-2007 cr125 as well. So if you have either of these bikes
Definitely something you want to consider. There's another issue with this design as well. And that's inside the airbox. There's all these little nubs
Where the air filter sits on the airbox and it's supposed to seal right there and obviously having those nubs
Doesn't create the best seal and a solution for that is a gasket called the pro seal
It's like a rubber or foam type gasket. It just sticks through the airbox
You can see it's a little bit thicker and has all the cutouts for the nubs
so basically just raises up that surface there to the top of the nubs and
Allows the air filter to steal a little better and later in the video
I have a better kind of more permanent solution for that
This is kind of a quick fix, but I'll link this little gasket down below in the description
Now the most important issue here is the air boot to airbox seal
so discuss the three solutions I have for that and the first one being the cheapest and easiest way to fix it and that
Involves using some Permatex liquid gasket like gasket maker. This is the ultra black
basically, what we're going to do here is put a generous amount on the lip here all the way around the airbox and
Then we're gonna mate up
the boot onto there
Let it tack up before tightening it down. See what the
Instructions say here. Looks like it tacks up in an hour and then you want to let it dry for 24 hours before use so
Once again, get the sealant on there put up the boot
don't tighten it down all the way let it dry for an hour and then snug it all the way down with the screws and
That's not going to be a hundred percent guarantee that it's gonna seal and last
But literally it's like a five-dollar solution and I've heard of a lot of people having good luck with this
Basically you want enough sealant on there, too
When you put the boot on it uses out the edges just a little bit
But keep in mind this isn't going to be the cleanest or prettiest solution, but it's effective now
The second solution is a bit more involved, but the end result is a lot cleaner and it's more effective
so the basic concept here is to adapt an air boot and the air filter mounting plate from a
97 to 99 cr250 onto this air box that design was a lot better and pretty much foolproof
It's something that Honda should have stuck with so how we do that is by cutting out the center portion of the air box here
Dropping that out
And then the 97 to 99 air boot has a dual lip just has an extra flap that comes out
One lip goes on the inside the air box and one goes on the outside
So it's like the perfect seal and I don't have a dual lip air boot to show you guys what that looks like
so I'll put a picture on the screen so you guys can see and
As far as the air filter mounting plate, it's metal and replaces this cheap little plastic one inside here
so it's not gonna flex like this one does and that has studs that come through and
Bolts the air boot onto it so a really solid solution, but it takes a little bit more time
and you have to find the 97 to 99 air boot the air box and all the
Components inside as well and I'll actually drop a link down below that explains more about this setup. It has pictures
Right up. This is a really comprehensive tutorial on how to do this modification
keep in mind this mod only works for the C or 250 s because the air boot only fits on the 250 carb and not
the 125 card now the third solution and the one we'll be using is
This one that has aluminum plates one goes on the inside the air box one goes on the outside and in my opinion
this is the most effective way and
You don't have to do much in the way of cutting
So the basic idea with this solution is you have two lumen plates. You bolt them together with the air boot in between
they're obviously not gonna flex they're pretty thick and
They're not going to create any air gaps between the air boot in the air box or between the air filter
and on top of that you shave off these little nubs inside that I was talking about earlier and
That creates a good seal between the air filter and the air box
And before we get started got to make sure all of the old sealant
Gasket dirt grease all that stuff is off the air box in the air boot now
the first step is to drill out all the mounting holes for the air boot and the size we're using is a
257 so 2.25 7-inch. It's
One size up from quarter-inch. So we're gonna drill all the way through these holes obviously try to be as straight as possible
and
all the way through
The nub on the other side since the air box already has little holes there
Those will act as pilot holes and that should make it pretty easy
After drilling you're gonna have some birds around the holes. So you want to trim those off with a scalpel or a razor blade and
Make sure all of these nubs are the same height when you're all done trimming
So now the hole should look something like this now
The next step is to go inside the air box and trim off these nubs that we drilled through
You want to trim them all the way down to the surface? You don't want anything poking up
Got all the nub shaving down not the Tydeus job kind of takes a while, especially with these lower ones
It's pretty tough to get down in there. But the tool I found that works best for this is a little scalpel
I'll link it down below. It's pretty nice for shaving gaskets, too
I'm gonna go ahead and test fit the plate make sure it's a snug fit
Sweet stroll the holes line up
All looks good
Now before I slap this together, I'm gonna seracote these plates black. I want them to match the air box
I think that would look pretty good
The plates are looking good all done with sarah coding and now we can slap this whole kit together
So we're gonna put sealant on the inner lip of the air box here as well as this lip around the outside
And then seal that's going to go on this side of the ring too as well as the inner lip of the air boot
The sealant should look something like that when you're finished up
every bit of that surface should be covered and
Then the inside of the air box should have a nice fat bead all the way around as well
It's got to make sure there's no way dirt can get through that now
I'm going to get this plate set in place in the air box and then get to work sealing this side
All right, I think we're ready to slap this thing together just gonna line up the boot here
Gonna start popping in some bolts here make sure everything lines up
Damn glove got stuck in there get out of there
So things weren't lining up the greatest
so what I did was put all the bolts in from the inside get that inner flange lined up with the air box and
Now I'm gonna line up the air boot. Hopefully this works a little better this way
Honestly this outer plate really isn't lining up too good for the holes
Look like they're fine. But this
fifth hole right here is a little bit off and
That's holding us up from being able to put this together looks like an got it
Lined up right now if I can get this one on the rest of them should be pretty easy got that one lined up
This one looks like it'll go
All right
So we got all the bolts lined up took a bit of work to get him to go
But I would recommend doing these two bolts first
These are the harder ones once you get those lined up the other three should be pretty easy
So now that we've got all the nuts on I'm gonna tighten them all down evenly so I'm gonna go in a crisscross pattern
Here kind of like you're tightening a five lug wheel
Got everything tightened down and looking good and within an hour before that sealant starts to dry
You want to clean up the excess around the edges?
Looking pretty trick now for the filter cage you want to make sure that it fits
Snugly against this inner flange. You don't want to see any air gaps there
Looks like it's pretty tight seal all the way around won't need to do any trimming to get it to fit better
So that looks like a go. I think we're all set
So just let that RTV sealant dry for 24 hours before using the air box and then we put an air filter on
You want to grease the inner lip here at the air filter where it fits against the air box?
So that'll ensure even further that no dirt gets past your filter
The very last thing I want to do this air box is make it look good and keep it looking good
So I'm gonna get rid of some of these scratches
Son fading and kind of pitting back here
so I'm gonna hit it with like 800 grit sandpaper just for a little bit and then finish it off with the
Seracote trim coat. This will give it a nice shine and it says it lasts for up to 200 washes
So let's give it a shot. I've got the air box all sanded down
Now before that coating can be applied the air box has to be clean with dish soap and completely dried there
Can't be a speck of water on it
So basically just wiped down the air box with the cloth inside and then to give it a consistent finish
You just wipe it in the same direction like this to finish it up
All righty guys air box is all finished up looking absolutely
Amazing honestly looks better than new and works better than new too
so like usual
I will have all the products they use throughout the video including the aluminum plates
the seracote the trim coat all
Link down below in the description for you guys to make it easy and one thing I didn't mention about the trim coat
It's a ceramic coating
So it has anti stick properties and you guys know how dirty the inside of these air boxes get over time
So I actually think the trim coat will help keep them clean. I'll keep you posted if that works or not
Here's another look at the finished product here
Literally looks brand new. This stuff is freakin incredible
Definitely worth a shot and I believe seracote offers a free sample on the website
I can find that. I'll drop a link down below
Thank you so much for watching the video guys and like always if you enjoyed it. Make sure you go ahead and share it
I really appreciate that. So expect to see a lot more videos with the cr250 coming out pretty soon in the next couple weeks
We got some really cool parts showing up. So that thing should be done sooner than later. I'm excited
That's all I got for you today until next time keep it brand
You