Air Box Delete

[Ausm7499]

I got tired of trying to keep the snow out of my airbox so I decided to delete it and try something different. I also have been having some carb icing issues so I installed a KTM carb heater. For the intake I used a 3" chunk of 2.5" silicone hose that just barely slide over a 2"X3" ABS reducer I then used a 3" - 22.5 degree ABS elbow to clear the subframe and then drilled out a 6" long piece of 3" ABS to use for my prefilter cage which I will be running an outwears prefilter over. Installing the carb heater was a lot easier than I thought it was going to be and aside from drilling a hole in the carb and tapping it for the heat probe everything was plug and play.

I haven't taken it out on the snow yet to see how this new setup is going to work but I am headed out Monday and I will report back. My bike is looking pretty bare with the radiator shrouds being the only plastic left on the bike but I am thinking this new intake should give me a lot less problems.

 

[SNOADDICT]

Looks good I tried something very similar to this last year but I couldnt get enough air at full throttle. I had mine run up through my rear fender with a 2" hose all the way up, I think that was the problem my hose was to long and the air stated to create some sort of a resanation in the hose. Im actually surprised no one has come up with some sort of aftermarket airbox replacement snorkel kit for these bikes as that was the main reason i sold my kit i couldnt keep snow out. Hope it works good for you, let us know how it works.

 

[up-high]

That looks slick. What about running the end up past the back of the seat to keep it out of the snow?

 

[SNOADDICT]

Ya thats what I did was run it up through the rear fender but like I said it didnt work. I was running a 505 and it just couldnt breathe. these timbersleds do throw alot of snow back towards the motor so I would keep an eye on the preilter as In my opinion its going to take a beating down there.

 

[up-high]

Maybe the diameter of the hose wasn't big enough? What did you use for a filter? Did the hose have sharp angles or smooth transitions?

 

[Ausm7499]

Initially I was going to make it more of a snorkel and run it up to the back of the seat with 4" ABS because I didn't think the 3" was big enough but I can't find a prefilter to fit over 4" ABS so I am going to try this and see how it works. I agree a lot of snow gets thrown through the subframe of the kit but I am hoping it just falls off of the prefilter and doesn't effect airflow that much. I will let you know how it works after Monday's ride.

 

[dirtrebel]

I cover the underside of my tunnel with thin plastic to eliminate the snow through subframe and find it helps alot even with conventional airbox. I run flowrite vents in the side of the airbox and a prfilter on stock foam filter and seal the crap out of the airbox. I would be careful with the prefilter only I have never been confident enough to eliminate some sort of foam filter. If the prefilter fails for some reason you will suck in snow and alot of it. If the foam stays DRY it is fine the problem I find is that if the foam gets wet and or snowcovered it wont work. Not trying to diss your idea as I like the snorkel idea alot I think if you can eliminate the spray through subframe with some covering it will help that snorkel stay safer. I think the best place for a snorkel is up by the number plate. if you could keep the airbox and come up under the seat to that area would be sick. Don't know about the sound thought? Just my.02

 

[Revv Up]

I applaud your efforts and hope they work out as I gave that setup some consideration but..... the KTM airbox is not that hard to make snow free.

Yesterday were were out in atleast 2' of fresh powder with no airbox issues (I did take the cover off a couple of times and there really wasn't enough snow in there to worry about)

Make sure to give us a report on how it worked out for you.

 

[TeamOrange]

I have had problems with carb icing on my ktm/2moto. I was thinking the outerwear was a waterproof membrane material and it had a leak somewhere so i took it off and ran it under a fawcet. To my suprise water ran through it pretty much like nothing was there at all! Your extention you built looks like it will just relocate the intake farther aft on the bike. The way i would mod your design is to replace the tube with holes drilled into it with a heavy stainless mesh and make it make it a larger surface area by either being longer or larger diameter or both and use an outerwear material which wont pass water. I was thinking just using carb heat might work but i am worried about so much water being run through the engine. I guess my point is that the black tube with holes in it seems restrictive. Hopefully im wrong and it works perfect. We will learn from your design either way. Good luck

 

[Ausm7499]

I started off the season running just the prefilter and filter cage without the foam ( I see no need to use the foam filter) and the bike has ran good until I get snow in the airbox. As for sealing the airbox I had spent quite a bit of time and effort to seal it and somehow I was still getting snow in it when the powder was deep. I also don't like that any moisture that gets into the box ends up in my intake because that is the lowest point in the airbox. I am not to worried about any restrictions with the intake I built it should flow plenty of air for a little 300, I have seen sled intakes much long and restrictive feeding much bigger motors. I am going to take some duct tape with me and if it seems I am having to much snow coming through the subframe I will tape off the openings. I am headed for the mountain tomorrow and I think we are going to have about 2' of fresh so it should be a good test, I will report back.

 

[more snow]

It also would be a good idea to put a ziptie or hose clamp where the prefilter material seals up against yoiur black pipe setup. Otherwise, snow will work past this interface.

 

[Ausm7499]

It also would be a good idea to put a ziptie or hose clamp where the prefilter material seals up against yoiur black pipe setup. Otherwise, snow will work past this interface.

I don't think I really needed the zip tie to keep the snow out because the elastic sits behind the lip of the collar on the elbow but as a safety precaution and for piece of mind I did put a zip tie around it. Overall the intake performed very well and was noticeably better than the airbox especially considering the snow conditions. We were riding in about 2' of pretty fluffy powder the type of snow that likes to get into your airbox and ruin your day. Even with the intake as low as it was and the constant snow being thrown on it from the track it never got completely covered or clogged up, most of the snow just fell off of it. When I stopped I usually just brushed what snow was on the prefilter off. I think the engine is getting plenty of air from the intake although I may have noticed a tiny bit more hesitation low in the rpm but it could have been my jetting to I will have to ride it more to see what the culprit is. Another problem I had was on the road ride back to the pickup the bike started running rough and would die as soon as I let off the gas, when I got home I pulled the intake of and found water droplets all over inside the intake and I am betting my float bowl is full of water and that's why the bike was running so rough. So the prefilter is letting moisture through in one form or another which is probably happening with every snobike setup but to combat this I am thinking about adding some isopropyl to the gas so the water mixes instead of collecting in the float bowl. As for carb icing I think I may have experienced it once thoughout day when the bike didn't want to idle very well but it could have been the water in the fuel to it's hard to say. I also need to verify that my carb heater is working, I put my finger on it after the bike had been running for awhile and didn't feel any heat so I may have a wiring issue or it may not get that hot at the top of the probe I will do some testing this week.

As of right now I am happy with the intake and am going to continue running it, I feel like it's going to give me a lot less problems than my airbox. A previous comment on this thread stated that the KTM airbox's are easy to seal up and I would agree with you if your talking about the older airbox design as I didn't have near the issue with my 06 525 as I have had with my 09 300 airbox. I think the newer KTM's 11 and up have a different airbox design that is more forgiving in regards to keeping snow out.

 

[Leftys]

The kit looks good. The only thing that I see that can potentially be a future problem is there is no support at the pre-filter end of the tube. The weight hanging off of the carb is a lot of stress on the carb to cylinder intake boot, especially with the vibration of the engine. Something may be there, but I am not seeing it.

On the idleing and water in the Float Bowl situation. Here is what I have found: The Jet Needle is iceing up so when you close the throttle slide the Jet Needle goes into the Needle Jet and blocks fuel flow and emulsification with the air creating a lean condition, which will not let the engine continue to run. When the ice melts off of the Jet Needle the water drains straight down into the float bowl. After a few times of this happening you have water in the bowl.

 

[Ausm7499]

The kit looks good. The only thing that I see that can potentially be a future problem is there is no support at the pre-filter end of the tube. The weight hanging off of the carb is a lot of stress on the carb to cylinder intake boot, especially with the vibration of the engine. Something may be there, but I am not seeing it.

On the idleing and water in the Float Bowl situation. Here is what I have found: The Jet Needle is iceing up so when you close the throttle slide the Jet Needle goes into the Needle Jet and blocks fuel flow and emulsification with the air creating a lean condition, which will not let the engine continue to run. When the ice melts off of the Jet Needle the water drains straight down into the float bowl. After a few times of this happening you have water in the bowl.

The intake is supported with the white ziptie that goes around my strud rod, it does a pretty good job but I want to figure out a better method.

Your water in the float bowl diagnosis sounds legit I think next trip out I am going to try wrapping some insulation around my carb and I need to verify if my carb heater is working. If I can keep the carb from freezing it sounds like I may resolve my water issue.

 

[Revv Up]

Hows about a crazy carpet ziptied to the upper frame to act as a fender for the offending snow being thrown?

 

[Ausm7499]

Hows about a crazy carpet ziptied to the upper frame to act as a fender for the offending snow being thrown?

That's a good idea I think I will do something like that.

 

[Revv Up]

I may have stolen that idea from Carbondaddy

 

[Ausm7499]

I now have two ride on this intake in 2ft of powder and am having minimal issues compared to the airbox setup. I didn't get time to address the issue of snow coming up through the subframe on the kit or wrap my carb with anything and it still ran pretty good. About halfway through the day I had to turn my idle up to make it idle but other than that it ran good. I really do need to put something around my carb though because it is completely covered with snow all day and I don't think that little carb heater can compete very well against that. I also know that I was sucking snow into the carb but it didn't seem to effect performance of the bike, the powder was so dry that it must have been making it's way through the prefilter because I could see snow inside my intake.

 

[dirtrebel]

trying this today

gonna try this today 2" radiator hose (rubber fuel should not melt it) to a 2" conduit 45. Foam filter with prefilter socks i made from organza. have 2 or 3 spares to put on if it gets wet. for me I am doing this because the airbox is to hard to service in the field.

 

[Telekiter]

gonna try this today 2" radiator hose (rubber fuel should not melt it) to a 2" conduit 45. Foam filter with prefilter socks i made from organza. have 2 or 3 spares to put on if it gets wet. for me I am doing this because the airbox is to hard to service in the field.

Pretty decent looking MH-copy you got there, care to elaborate on that DIY-kit .

Here is a picture of one that two Swedish guys made. Kind of nice don´t you think.



/Urban.