Modifying/cutting airbox on KTM 300 for Velocity Intake, tips/suggestions welcomed

Ben 500RR-S · Dec 4, 2018

We have a SmartCarb on the way along with a PST clamp on carb heater, thermobob, trail tech thermometer and carb jacket. A Velocity Intake is also involved and I understand that the airbox will need to be modified/cut to fit it all.

How hard is it to remove the airbox on the 2008 KTM 300?

Is it also easy enough to cut?

2smokin · Dec 4, 2018

unbolt what you can, im trying to recall hoe the 08 looked, anyways i found it nice to unbolt the bottom of the subframe and swing it up. i cut mine with an angle grinder and just swung it back down to check fit. makes doing carb work super easy as well.

Answ3r · Dec 5, 2018

Care to show what is a "velocity intake" ?

Ben 500RR-S · Dec 5, 2018

Answ3r said:
Care to show what is a "velocity intake" ?

http://www.powersportstech.com/pst-velocity-intakes.html

From what I was told, because a SmartCarb, along with the clamp on heater, is so large, while I can use the reed cage side of the intake, the carb will be too big to fit on the airbox side so I have to modify the airbox and the Velocity Intake from PST is the solution.

Ben 500RR-S · Dec 5, 2018

2smokin said:
unbolt what you can, im trying to recall hoe the 08 looked, anyways i found it nice to unbolt the bottom of the subframe and swing it up. i cut mine with an angle grinder and just swung it back down to check fit. makes doing carb work super easy as well.

Thanks so much. I appreciate it.

I never thought of swinging the subframe up. I just did it on a 2008 CRF450X to get the carb on and off, thanks for the tip as that is exactly what I'll do.

I think I'll get thee to Harbor Freight to get one of those Fein-like tools for cutting the airbox.

Ben 500RR-S · Dec 5, 2018

The bikes, this past Saturday.

n16ht5 · Dec 5, 2018

Remove airbox all together.

Ben 500RR-S · Dec 5, 2018

ChrisNeibauer said:
Remove airbox all together.

Thanks.

I think this will be better than me hacking away at the airbox.

I had heard, though, that the KTM airbox is a mess. That it is not simply bolted on like every other Japanese bikes airbox, but KTM did some overly complex plastic origami to get the airboxes together but(and here comes the butt), once removed or cut, the entire airbox assembly/or all the parts are about $50.

I think I would rather take the thing off and then put it back on if the bike needs to go back to dirt than hacking it up and then having to replace it anyway.

n16ht5 · Dec 5, 2018

Have to do some wire and battery finagiling, its worth it though. Sheds snow way better too.

Ben 500RR-S · Dec 5, 2018

Might there be a way to leave the battery in its cozy little home?

I can't even begin to think of where or how I'd secure the battery of the space it is now has to be taken out.

I'll have to go and bring the bike home this Friday night so I can get this next project started.

KTM_FREERIDER · Dec 5, 2018

I am doing the same intake on an 18 KTM 450. I was hesitant to start hacking on the air box so I asked one of the local expert KTM Snow Bike guys and he said to get rid of the complete air box and to only run the Velocity Intake because of the type of snow we have in South West MT. I also talked to Brad from PST yesterday he confirmed to remove the complete air box as well.

Ben 500RR-S · Dec 5, 2018

KTM_FREERIDER said:
I am doing the same intake on an 18 KTM 450. I was hesitant to start hacking on the air box so I asked one of the local expert KTM Snow Bike guys and he said to get rid of the complete air box and to only run the Velocity Intake because of the type of snow we have in South West MT. I also talked to Brad from PST yesterday he confirmed to remove the complete air box as well.

Great! I just spoke with Brad at PST this past Monday and Tuesday. He was the one who had told me to remove the airbox.

How are we to mount the battery?

Did they mention how the box comes out? Brad had mentioned that it is not just bolted in and just that easy to get out. I'm not looking forward to getting it done but will just have to suck it up and do it.

I also forgot to ask, someone, but, with no support at the rear of the carb/the intake side, what happens to all the weight on the reed-cage part of the intake when the bike is getting jammed around in the snow where normally the airboot is there to help keep the carburetor in place?

KTM_FREERIDER · Dec 5, 2018

I am not sure how the battery is mounted on the 300 but I attached some pictures of my 18 450SXF.

As for removing the air box, I will just be honest and tell you that its not the easiest to remove. I removed all the plastics from the fuel tank back and then removed the two bolts on the lower aluminum sub-frame and loosened the two bolts at the top of the sub-frame behind the fuel tank and pivoted the sub-frame up. After that you will fight with sliding it off the sub-frame for probably a good 20 minutes until it finally decides to slid off.

CATSLEDMAN1 · Dec 5, 2018

well ok

KTM has complicated plastic. ?? not sure why. BUT. my riding partner and i have same year KTM bikes 450 & 500, 2013, he is running no air box with snorkle, I have stock air box with bottom cut out, stock filter dry with frogskinz cover.
Often on blower powder days his snorkle plugs and I can ride in elbow deep powder, never skipped a beat ? I was told when I bought my 500, go cut out air box, no snorkle, so far cut box is fool proof.

I made a 2' long snorkle covered with coarse foam and frogg skinz cover for a YZ250 I ran. In the wrong condtions I totally plugged, one swipe and it was running again, stay away from deeeep powder you can't go wrong.

2smokin · Dec 5, 2018

KTM_FREERIDER said:
I am not sure how the battery is mounted on the 300 but I attached some pictures of my 18 450SXF.

As for removing the air box, I will just be honest and tell you that its not the easiest to remove. I removed all the plastics from the fuel tank back and then removed the two bolts on the lower aluminum sub-frame and loosened the two bolts at the top of the sub-frame behind the fuel tank and pivoted the sub-frame up. After that you will fight with sliding it off the sub-frame for probably a good 20 minutes until it finally decides to slid off.

When i looked at how it was all attached i couldnt get over what a pain in the ass it was, i wanted to try keeping my side panels though so i just cut the inside and bottom of the airbox out. so far so good most of my snow build up is around the chain where the kit meets the frame. whereabouts southwest montana are you out of?

KTM_FREERIDER · Dec 5, 2018

I heavily debated on wether to cut or remove and then after some advise I removed. I am still in the assembly process but last night I did a mock up of the plastics and from what I can tell all the plastic will go back on.

Bozeman/Belgrade area

Ben 500RR-S · Dec 6, 2018

2smokin said:
When i looked at how it was all attached i couldnt get over what a pain in the ass it was, i wanted to try keeping my side panels though so i just cut the inside and bottom of the airbox out. so far so good most of my snow build up is around the chain where the kit meets the frame. whereabouts southwest montana are you out of?

When I get the bike back on Friday and get a chance to check it out, I'm going to weigh cutting vs gutting.

I'm more inclined to cut, especially if removing the airbox means needing to figure something out with the battery and all the cables/wires/harness'. I'm no fabricator at all.

2smokin, why did you have to cut? Did you install a snorkle for your intake?

Ben 500RR-S · Dec 8, 2018

I had the time this afternoon to get the airbox off.

While not a total pain, it was not too bad either.

I took the rear light assembly off and we will be leaving it off as there is no need for it at all.

A big 17mm nut came off at the junction of the orange rear fender and the inner liner. The battery unit and the three self tapping screws had to come out and once the two cables for the battery box are snaked/moved out of the way, the subframe can come off and the airbox unit can be slid down and off of the subframe uprights. They didn't just slide on down, the entire thing took some coaxing as the unit is molded around so many of the subframe's parts but once I got it started and moving, it came off.

I drilled three holes in the top of the Camso tray and bolted the battery box to it. Thankfully there was enough length in the cables to reach the tray and I had to also run a new ground wire to the subframe.

Now to wait for the SmartCarb, PST carb heater, Thermobob and Velocity Intake to arrive so I can get them all in. Ahhhh, progress.

Vincenthdfan · Dec 9, 2018

Ben 500RR-S said:
I had the time this afternoon to get the airbox off.

While not a total pain, it was not too bad either.

I took the rear light assembly off and we will be leaving it off as there is no need for it at all.

A big 17mm nut came off at the junction of the orange rear fender and the inner liner. The battery unit and the three self tapping screws had to come out and once the two cables for the battery box are snaked/moved out of the way, the subframe can come off and the airbox unit can be slid down and off of the subframe uprights. They didn't just slide on down, the entire thing took some coaxing as the unit is molded around so many of the subframe's parts but once I got it started and moving, it came off.

I drilled three holes in the top of the Camso tray and bolted the battery box to it. Thankfully there was enough length in the cables to reach the tray and I had to also run a new ground wire to the subframe.

Now to wait for the SmartCarb, PST carb heater, Thermobob and Velocity Intake to arrive so I can get them all in. Ahhhh, progress.

Pics....we need pics!

Ben 500RR-S · Dec 9, 2018

Man, I have been trying to upload pictures for a while but my digital camera takes 12MP images. I just tried to go down to 9MP and they are still go big to upload to this forum.

The pictures would be very underwhelming, there is just no airbox and carburetor though the battery box is now bolted to the top of the Camso tray.

Eventually a PST Velocity Intake is going to go on the end of the SmartCarb, like in this link;

http://www.powersportstech.com/pst-velocity-intakes.html

Modifying/cutting airbox on KTM 300 for Velocity Intake, tips/suggestions welcomed

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