Hello, John Talley here with Partzilla.com, and welcome back to our
next installment on our 2018 Honda Grom build. Now today, we're going to be
focused in on the intake system and the exhaust, actually. We're gonna change out
the throttle body, we're gonna put in a high flow injector, we're gonna have a
high flow air filter, and then all that's going to be funneled out through a new
exhaust system. Now this is part two of three if you want to loosely call it the
engine build. Now when we get to part three, that's when we'll deal with the air
fuel management. The neat thing about this one? When we're through building it,
we're actually going to give it away. So if you would check the link in the
description below it'll carry you to a landing page where you can enter to win.
But if the contest is already over, why don't you leave this little note in
the comment section and tell us what machine you'd like to see me modify and
then us giveaway. So that being said, let's head over and get started on this
one.
So the goal here over at the teardown bench is to make this resemble what came
off. So we're going to start off by transferring over the idle air control
valve as well as the throttle position switch. Alright, they are held in place
with Torx and the screws and it's a T25. So we'll start off with our throttle
position sensor. See if we can gently pry up on this. There we go. Then just
transfer it over. It just bolts back in place. Now there is no adjustment on this
one. I've seen on other units like TRX 420 where this is actually slotted and
you have to dial it in by taking a resistance measurement. Evidently on the
Grom is not the case: one location period. Now since we're over on this side, let's
go ahead and grab the air fuel or the idle fuel mixture screw. Now we're just
going to transfer that in. We're gonna lightly bottom it out and then back it
back out two turns. Alright, that's bottomed. One, two. Next let's go for the
idle air control valve and that was the T25 as well. Who would have thought so
many years ago a simple little minibike would have all this complicated stuff on
it now. Guess I'm really showing my age, huh? Well
the basic design of a minibike, when you think back to a QA 50, just had a simple
carburetor on it and now here we are a fuel-injected, and throttle position
sensors, and everything else of a modern machine. Now let's go and mount the
throttle body to the actual intake.
Get our O-ring. I'm just gonna sit in like this. And we're just reusing the two
eight millimeter head bolts that came out of the OEM, the original that is. Yeah
I believe we need to get that bracket over here. Compare these two. Tell me
that ain't gonna be pulling some more air. Big, big difference. Now all these pieces
when they all come together, it's gonna be nice. We're gonna go ahead and put
this little spacer in place. Now you've got these three threaded areas here, and
if you have the stock injector going back in, you just use those two. But ours
is just gonna use the single one in the middle. Now let's get our adapter kit and
get our high flow injector in there. Now one note, with this particular setup on
the 2018, the input was going to interfere with the plug going to the
idle air control valve. So, I just heated it up a little bit and bent it up enough
to clear it. Wasn't in the instruction book, but that was my way around it. Now let's
work on our injector. Now this one actually has an o-ring around the bottom,
so you will not be using this other rubber o-ring if you want to call it
that because that is actually made for the the stock setup-- or the stock
injector. Now, need to set up our adapter on top of our injector. That goes in
there, and then this little clip slides in to
hold it in place. Now we'll take this assembly and push it into the intake and
you should hear a click once that o-ring seats properly.
Now put in this other five millimeter hex and it'll hold the injector in place.
Now if you're looking at it from the side, what I did was modify this angle because
before it was just sitting straight and there's no way that plug would have been
able to clear. So, just bend it up a little bit, that should give us enough
clearance. We've pretty much got it together, now what we need to do is adapt
this down. So you've got this length of hose and then this brass adapter. Now
let's wrangle this hose onto the end of that adapter. What I'm doing here is just
pre stretching it a little bit so they don't give us much room. Because this is
actually too large compared to the one that came off. That is some type of
tight fit there. So we just need get clamps on then we'll be ready to install.
The chances that this actually blowing off are almost zero without the clamp
but we're going to put it on there anyway. So I think it's got right at 48
psi from the fuel pump in the tank? Last but not least, we have an adapter to go
on our injector. Alright let's get it bolted up to the machine.
The arrangement they have here, this gasket, spacer, then another gasket, and
then the intake itself. So you just sandwich them together like this. Stay.
This all goes together using the bolts that were holding it down to begin with.
When you're doing this other side, don't forget your little bracket that's gonna
hold the the air box in place. And that forward bolt that was in place doesn't
want to go now so we had to put in a shorter one. Let's make a few connections
now. Throttle position, and intake air, fuel injector. There we go. Now we go into
our fuel line, just push in and that should let it go through. Made a little
boo-boo guys. I actually put the adapter in backwards so we're gonna need to
remove it from the hose, flip it around, and then reinstall it. Through the magic
of editing, this just got spun around and reinstalled like it's supposed to be. Now,
there we go. We're gonna add in a zip tie just to
hold it in place up top along that frame spar and harness. Alright guys, we've got
our intake mounted, we've got our new injector, our a new throttle body, it's
ready to go. So we're gonna go grab the exhaust and
we'll get started on that. Let's start off by installing our studs for the
exhaust manifold, and the best way I know to do that is to take a couple of nuts
and just have them face each other, lock them down, and then you can drive it in.
So let's get this little plumbing puzzle put together. Take your header and go
ahead and put it into the mid pipe like this. And they want you to use this bolt
with this washer and it's supposed to go through here and then go into this
existing pickup point where the other exhaust was mounted. That is not going to
make it. So that is a little too short, I'd say about 10mm.
So I'm going with a little bit longer bolt. This is theirs versus mine,
so it can bridge that distance. Hopefully you have one of these in your extra bolt
pile as I do. And at this point, put your exhaust gasket in place. Now we're gonna
lift it up. Now you want to use the bolts that came off the stock exhaust system.
So we've got it loosely in place, I'll jump over on the other side and stretch
the spring in between the head pipe and the midsection. Now we're going to put on
the actual muffler, and because we are using a different foot peg set from
Driven Racing, we have to adapt it a little bit to get it to fit because
we're actually going to be a little bit short when it comes to coming out to the
mount for the muffler itself. So I'm just adding in a spacer to accomplish that
and then I bought a longer bolt to go all the way through. Just, you start
modifying things, this is what you run into and you just have to figure out a
way around it. Welcome to the world of modifications. I think that'll do, plenty
of clearance in between the swing arm, this bolt, and the muffler itself. So now
I think we can start to actually tighten everything down. Let's start up at the
head pipe first, get it snugged down. After you've run the bike for a while,
you may need to come back and re-tighten these. As the head and the exhaust gasket
expand and contract, it may develop a little bit of a leak and just needs to
be tightened back down so it doesn't burn through the actual gasket that's up
inside. Let's get that mid mount.
Last not least, the rear. And we have one more spring to install. It's not as if
this is going to jump apart but we want to go and install the spring. Now there's
one thing left to do. All this nice clean stainless steel has not been heated up
yet, but there's fingerprints all over it. So if we run it right now without
cleaning it, those fingerprints are gonna actually get embedded and turned up
being blue and we don't want that. So we're gonna get some contact cleaner and
a towel and wipe those down to where it is going to be ready for the first start.
So now let's turn our attention to installing the air box and the new
filter. With a larger throttle body we of course have to adjust to it, going from
the air box that we're gonna use. So we're gonna have to modify our existing
air box to get the new tube into it. As you can see, it's much larger. So let's
get this taken apart, get the old tubes pulled out, then using a dremel tool-- a
bur tool-- I'm gonna enlarge them to where they fit correctly. Just for kicks,
look at your surface area, one compared to the other. I believe that's gonna flow
a little bit more air, which this machine's going to need. So let's start
by getting this tube extension out of the way.
Of course that's melted in place, so I'll tell you what, we'll just ground that off
then that should release it. If you decide to grind like I did, just make
sure you get all of the shavings out. We don't want to pull that into the engine.
So we don't damage the intake air temperature while we're doing all this,
let's go ahead and remove it and put it to the side. And then we'll work on
breaking that glue loose, not gonna be that tough.
No glue on the second one. Now all we have to do is make both of these fit
there and there. What they call for is this opening to be 40.5
millimeters. What I'm gonna do is use my caliper to find a socket with a diameter
really close to that. A thirty millimeter socket is right at forty
millimeters. So that's going to be as close as I can probably get. So what
we'll do is lay it there, scribe it with a sharp point, and then hand cut it. This doesn't
have to be absolutely exact.
Let's do a test-fit and see what we've got.
I'm liking that. Pretty sure I've got it upside down, but fortunately I took
a picture before I removed the other one so I can get it back at the same angle.
Now for the 50 millimeter we're actually going to look at a 36. It is 50.1. Winner.
Let me do a little housekeeping, then we'll get going. Alright, according to
my phone, this one needs to sit about right here. And
then the intake is about right there. The final say-so's, we'll hold it up to the
machine and see if it correlates. So now that we've got it pointed in the right
direction, what I'm going to go back and do now is push in on it all the way
around and a little about little get in some RTV sealant just to make sure we've
got the sealed up properly because that's that's the most important one.
Very important that we keep any other particles from making it past where
these two join together because that goes straight into the engine. I think
that'll do. Now let's get our intake air temperature back in. Now Koso sends
two different foam filters that can be used inside of the air cleaner adapter.
I'm gonna go with the the tighter one the one that's going to be more
aggressive as far as filtering everything out. But before we install it
I'm actually going to open it up and put a light coating of oil on the foam.
The combination of the foam with a little bit of oil that will block out the
majority of dust and particulates that are trying to get in. I'm going to use a
little bit of PJ1 foam filter oil and I want it on the side that the air's going
to draw through, cause I don't want to over-coat it.
That should do. Not absolutely necessary but too many years on a motocross track
makes me very leery of not oiling a filter before you put it in. Now we're
going to use the longer screws that Koso sent to mount the outside cover back on.
Alright let's see if we can wrangle this back on there. Go ahead and loosen this
stuff back up, and dip it down enough to where we can get it in there. There she
is. Now let's go ahead and get that clamp loosened up and get it over the intake
on the throttle body. Make sure it's on there evenly. That should do it. Grab
our upper bolts, go ahead and get the top of the air box mounted. Just a 10
millimeter on either side. Alright, let's work on those throttle cables next.
So what you want to do is put in your top-- your return side first and just
tighten it all the way down. And then when you're doing the pull side, you want
just a little bit of slack that you have to bring in before it starts to open up.
So just a little bit of slack just right here, and then tighten it down. Make sure
that it opens all the way up on its own. Yep, that's against the stop. That's set,
let's go and get our cover back on. We need to get the tank breather line
routed back where it started. And then we have the crankcase vent line that
actually goes into the backside of the airbox.
Alright guys, before I do my typical outro I need to show you a change I
decided to make on the intake system. Once everything had been put back
together, I'd never addressed the EVAP canister and the purge control valve. Now
there's a lot of people out there that just take the system and bypass it. Well
that's not the way I wanted to do it. I wanted to just modify and enhance the
engineering that came from Honda, and not eliminate anything. So what I decided to
do was actually cut into the factory intake far enough to where I could
remove that brass nipple vacuum then there's a location on the Koso unit
where you can see, well, that's where it should be. So I drilled it out,
transferred it over to the new unit and then put it back together. Well alright
guys, that's pretty much gonna wrap up this video but we are nowhere close to
actually finishing up this project. All of this new equipment needs to be told
how to operate and we're going to deal with that in an upcoming video. Now if
you'd like to see that video, why don't you hit that subscribe button. That way you
will be notified when we cut it loose. And once again I want to mention that we
are actually giving this one away so if you would check the link in the
description below and you can enter to win this exact machine. Listen, if you
have any comments or questions, why don't you go ahead and leave them in the section
below and I'll do my best to answer them. Listen we just want to say thank you for
shopping here with us at partzilla.com and we will see you in the next video.