How to install an Under Tunnel Exhaust on your 4-Stroke!

[sleddheadd]

looks Sweet!

 

[Rockmeister]

Mine has built up ice from the time I first got it.
Big clunkers... lol
Feel sorry for everyone behind me when they fall off!

Hasn't seemed to change much since the exhaust change.
They did get a bit smaller, think due to closing off the tunnel.
Had the exhaust on all last year, about 3500 miles.
Will watch it closer this year for it though, thanks for the input!

 

[nytroERrider]

Wow, thats a great write up! Dont you think when cutting or breaking that rear tunnel piece off will make it more easier to break? How did it break in the first place?

Jake

 

[Rockmeister]

Thanks!

The pot metal piece is paper thin, almost no strength to start with.
Had broke all on its own, yours probably has also if you look close.

The factory muffler actually adds strength to it.
So does the new mount.
The plate I added is MUCH stronger than it started from the factory.

There really doesn't have to be too much strength that far back actually, behind the rear suspension mounts, there isn't that much stress.

Lifting the sled from the grab bar, is probably the heaviest load it sees.
Thats why the tunnel extensions aren't that tuff.

 

[sobfrogg]

I cut the pot metal pc out to get my exhaust in. Just lock Rock, the exhaust supprt I put in gives the rear of the tunnel rigidity. Lighter and stronger then the cast pc.

Here is before I put in the brace:

 

[bdm]

When I did mine a couple of years ago I had two problems:

1) It is good that RM used a baffle. Without a baffle the glasspack resonated in my helmet something awful. I added a CC insert and that took care of it.

2) I am not sure if this problem was exhaust related but twice last season in bottomless powder I had a bog that was similar to if all of the hood vents were blocked, yet they were clear. In hopes that there was some kind of backpressure issue related to powder in the area between the track and the tunnel I extended the outlet to come out further back - way under the tunnel extension. We will see if that helps.

 

[SRXSRULE]

When I did mine a couple of years ago I had two problems:

1) It is good that RM used a baffle. Without a baffle the glasspack resonated in my helmet something awful. I added a CC insert and that took care of it.

2) I am not sure if this problem was exhaust related but twice last season in bottomless powder I had a bog that was similar to if all of the hood vents were blocked, yet they were clear. In hopes that there was some kind of backpressure issue related to powder in the area between the track and the tunnel I extended the outlet to come out further back - way under the tunnel extension. We will see if that helps.

In deep powder snow packs in under the hood and gets into the airbox and causes the bog. You need to buy some of that self addhesive foam tape. I like the 1.5" wide stuff thats around a 1/4-3/8 thick. place it on the under side of the hood where the hood seals down to the bellypan. the other thing is the aluminum bar the hood hooks under, make it fight tighter. Either adjust the bar down or add soem foam tape to the under side of the hook on the hood.

One last thing, then vents right in te center of the hood. they need to be tapped off. it works easy to remove them, tape off and put back in.

Keep the powder out of the air box and it will rip all day long in 3 ft of POW! Eric

 

[Rockmeister]

I have heard that from Katchess about bottomless powder creating backpressure, haven't seen it myself, yet we don't really get bottomless powder.


Here are some pics of the seat mount.

Rear View of Left Mount.

Inside View of Left Mount.

Had to re-use the factory J-bolts to pull the seat forward enough.
The perforated pipe strapping was supposed to be temporary, yet lasted about 3500 miles so far. lol

Hope this helps!

 

[rxrider]

Thanks rockmeister

That pics came in very handy as I'm just about installing my Apex seat on top of a REV gas tank.

If you have more pics of your seat mounts please email them to rxrider@bluezone.no

They will be a great help when on the install

 

[Bodacious]

Looks great I know another guy that did something very similar , the only problem was the tunnel built up with ice really fast , ( same issue as the Venture Lite and some Phazers ) ...The hot exhaust melts the snow and the snow dust kicked up from the track ..it was a real pain in the #*$&@ ....You can get a couple hundred pounds of ice built up under there .....Hopefully you don't have the same issue ...His solution was to extent it and bend it out the side of the tunnel...........

Just a thought about additional ice build-up...the 3 into 1 header pipe on the FX Nytro is totally exposed to the snows under tunnel turbulance, so it would seem that icing would be very heavy in the front part of the tunnel as well, maybe even more so than the muffler would create near the mid-rear section, being that the header pipe must run at even a higher operating temperture...?

 

[kyzer]

I don't think it's the heat form the exhaust it's self , but the hot exhaust air coming out ......When it's trapped underneath for a bit the hot air melt all the snowdust to the inside of the tunnel and it keeps building up....

 

[Rockmeister]

I don't think it's the heat form the exhaust it's self , but the hot exhaust air coming out ......When it's trapped underneath for a bit the hot air melt all the snowdust to the inside of the tunnel and it keeps building up....

Running in quite a bit of deep powder this weekend, noticed the ice build-up that kyzer is speaking of.

The ice build-up was more than it tends to be stock, totally filled the tunnel and covered the skid.
Working on a simple way to pipe the exhaust out from under the tunnel without creating too much noise and not interfering with the track, etc....

Here is more info on the ice build-up with a pic of it.
http://www.ty4stroke.com/viewtopic.php?p=577428#577428

Come to think of it, the sled would build up ice on my back before I re-located the exhaust...
The under tunnel eliminated that, but made this ice build up...
Hmmmm... need to figure out a way to eliminate both issues...

 

[Firemann32]

What year and model sled was this mod done on?

Reason I ask is the 1 Adapter NAPA# 735-1626 2-1/4 ID x 2" OD didn't fit. It needs to be larger than 2-1/4 on an 07' Apex Mtn.

 

[Rockmeister]

This adapter requires some modification, it has to be made into an oval to fit the "Y" pipe.
That is the only one that connects to the factory piping and would possibly be effected by a factory dimension change.
Where the "Y" is cut can also make a difference.
Had to file off some of the less than perfect seam lines on some of the parts for them to fit properly.

Is it close, or waaaaaaay too big/small?

This was done on an '05 RX-1 Warrior, many have done them on most other models.

Hope this helps!

 

[sobfrogg]

What year and model sled was this mod done on?

Reason I ask is the 1 Adapter NAPA# 735-1626 2-1/4 ID x 2" OD didn't fit. It needs to be larger than 2-1/4 on an 07' Apex Mtn.

I believe the Apex MTN exhaust will be the same pipe that is on my Attak. I have not measured it but it looks like 2.5" tall and 3" wide.

The apex pipe is different than the RX1/ Warrior pipe. The mod can still be done but a different adapter will be needed.

If you you can wait a couple of days I can cut my old Attak pipe and give it a measure