Tunnel Cutting

[Toad face killah]

So I know there are a few options out there for cutting a tunnel and doing it right. I'm a little hesitant cutting into a brand new sled but think the benefits in the powder sound worth it. Can anyone give a little advice with some do's and don'ts? I'm hesitant mostly because I don't want to screw anything up and leave a few shavings in the coolant system. I definitely dont want to take a chance at messing up my new warranty.....

I don't think I'd got the route of the MTN Tek coolant line mod to complete it, but would consider adding a tunnel cooler to make up for the coolant space I lost. I would probably go somewhere in the 7" cut range and do it right with welding it back together?

Any good thoughts out there from someone whos done it?

 

[neverenoughsnow]

i went with the MTNTEK kit first and ran hotter than hell.
the cut process is a pain, but must be precise. will make welding easier and it has to seal up. in the process of welding this week. i took a long skinny screwdriver with a small piece of paper towel around it soaked in brake cleaner to clean out the dust and pieces. just keep sweeping it with cloth till its clean. there are several videos on Youtube but they dont go into great detail. i cut around 7+" off and really like it. like how it dug in and kept going in the deep stuff. worth it, yes for those deep mountain days. if you want i may be able to send a couple pics that would help.

 

[couch]

After cutting I pulled the hoses from the bottle and the head and flushed filings out through the back while it was cut off ....

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[shattuck]

Maybe look into the b & m rear bumper it shortens things up quite a bit compared to most other bumpers without cutting your tunnel. I did the 163 track in the 155 tunnel last year and didn’t notice hardly any difference. I think you have to ride at a really high level for the short tunnel to be noticeable or help much.

 

[frntflp]

Maybe look into the b & m rear bumper it shortens things up quite a bit compared to most other bumpers without cutting your tunnel. I did the 163 track in the 155 tunnel last year and didn’t notice hardly any difference. I think you have to ride at a really high level for the short tunnel to be noticeable or help much.

Following -

I did the same last year to try the concept (and see if the new sled geometry is better with a 163 than RMK's of the past), so a 163 in a 155 tunnel. Not sure how much impact it had. Have a new sled on the way (165) and want to do a tunnel cut. Not a welder by any means. yes, I can cut the tunnel, that's the easy part - but then what .....

Update - decided to order a MTNTK kit. Fingers crossed.

 

[couch]

The aluminium extrusion is fairly thin ...need to be reasonably competent at al tig work or get someone else who is ..

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[IceAge Performance]

Being meticulous and thoughtful as you cut is critical. Like anything preparation is what leads to success. Clean cuts, clean welds. Cutting powdercoated tunnels is a little nerve wracking but its fairly easy to get it good looking in the end.

We recommend pulling the seat/tank and cowling then you can pull the lines as the front of the cooler. Once cut you can blast a ton of water then air down it ensuring the coolers are free of any debris. Also after welding before you fill it up with water, cap one side of cooler and add air to the other. Pressure testing beforehand has located a few tiny pinholes you would never see. A quick zap with the welder and your off vs having to drain and dry out the cooler which takes another hour at least.

It is very much worth it, we ran the 155 tunnel 162 combo last winter and ran some 155 sleds with shortened tunnels and hands down it makes a difference. The better a rider is the more they are able to take advantage of a sled that doesn't give up, just keeps digging.

 

[Toad face killah]

yea I'm still on the fence if it is truly worth the effort or not. I guess I've got time to contemplate waiting for my sled to get here. I do like the B&M fab boards that raise up the bumper and bring it in a bit. That'll be a start

 

[couch]

Being meticulous and thoughtful as you cut is critical. Like anything preparation is what leads to success. Clean cuts, clean welds. Cutting powdercoated tunnels is a little nerve wracking but its fairly easy to get it good looking in the end.

We recommend pulling the seat/tank and cowling then you can pull the lines as the front of the cooler. Once cut you can blast a ton of water then air down it ensuring the coolers are free of any debris. Also after welding before you fill it up with water, cap one side of cooler and add air to the other. Pressure testing beforehand has located a few tiny pinholes you would never see. A quick zap with the welder and your off vs having to drain and dry out the cooler which takes another hour at least.

It is very much worth it, we ran the 155 tunnel 162 combo last winter and ran some 155 sleds with shortened tunnels and hands down it makes a difference. The better a rider is the more they are able to take advantage of a sled that doesn't give up, just keeps digging.

Can't wait to try mine out!

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[boondocker97]

To the OP, even if you do it right you're still flirting with keeping your new warranty intact once you modify the cooling system. As always your warranty is only as good as your dealer, but as popular as this mod is becoming I wouldn't be surprised if Polaris investigates if the rear end of the sled has been modified.

 

[Wheel House Motorsports]

To the OP, even if you do it right you're still flirting with keeping your new warranty intact once you modify the cooling system. As always your warranty is only as good as your dealer, but as popular as this mod is becoming I wouldn't be surprised if Polaris investigates if the rear end of the sled has been modified.

If you do a good job i bet 90% of riders and shop techs would never even notice the sled is different unless you chop the thing drastically shorter. 5" off my khaos and most people just comment how i cut my snowflap off!

As far as performance. The more aggressive you ride an axys chassis the more you benefit from the chop. It makes the sled so much more capable in skis up tech manuevers and i found myself digging out of insane situations vs abruptly hanging track in the air and getting stuck. HOPING HOPING HOPING polaris sorts that out for '21.

 

[Toad face killah]

Thanks for the input everyone. I think just out of the spirit of a new sled and wanting to make it my own, I want to do it. I think a couple amazing days a year I hope to notice the difference. I live for the powder days, and if I can make those deep days just a bit better, then I'm in

 

[TallCan]

Instead of cutting your tunnel any downfall to putting 165 rails and track runder a 155 tunnel on 2021 Pro RMK ??? Think that my plan

 

[Sheetmetalfab]

Thanks for the input everyone. I think just out of the spirit of a new sled and wanting to make it my own, I want to do it. I think a couple amazing days a year I hope to notice the difference. I live for the powder days, and if I can make those deep days just a bit better, then I'm in

I really enjoy 7” shorter on my turbo 162.

Stuck? Naw just stand it up and whip it around.

 

[Sheetmetalfab]

Instead of cutting your tunnel any downfall to putting 165 rails and track runder a 155 tunnel on 2021 Pro RMK ??? Think that my plan

Just run without a flap and get a tucked in bumper.

 

[frntflp]

Instead of cutting your tunnel any downfall to putting 165 rails and track runder a 155 tunnel on 2021 Pro RMK ??? Think that my plan

I tried this last year (or close to it) bought 163 Ice Age rails and Series VI track. Worked pretty well. This set up keeps the tunnel in tact (as factory) and used stock or standard aftermarket parts.

However, the longer track pushed the rear axle back 4 inches. So I'm thinking that's roughly the same as taking a 163 tunnel and cutting off 4". Seems the most common tunnel cut is 7". Based on that, a 163/165 in a 155 tunnel is a good start, but not getting the full effect of a 7" cut on a 163.

The above said, I ordered a '21 Pro 165, and have a MTNTK kit on order with plans to do a 7" cut.

 

[damx]

This is my 163 stock tunnel, 165" track and kicked up bumper.

 

[frntflp]

This is my 163 stock tunnel, 165" track and kicked up bumper.

Tunnel isn't cut, at all ? Looks like my 155 tunnel and a 163 track/rails.

My 165 is in transit per an email received from Pol earlier this week - so still don't have a look at it. if the new 165's are set up like your pic from the factory, then I might just leave that part of mine stock (I,e, no tunnel cut) ..... hmm.....

 

[damx]

Nope, stock tunnel

 

[live2beel]

This is my 163 stock tunnel, 165" track and kicked up bumper.

What 165 track is that?