KTM300XC Build Project

[mtn-doo]

The e-start was perfect. Never has to turn over. Touch the button and instantly idles. First cold start and all through the day. Super convenient.

I am not sure about the LT with the 300. It doesn't rev as high as a 450F. Tops out around 9K. I feel the combination of that bike, engine are a match made for the ST. Will it turn the LT?, absolutely! 55HP is about what most 450F's make. The 300 is ridden aggressively and is super fast as a boondocker. I feel it is faster than my 450 banging the trees, others agree... however, if you want to sit down and cruise, that is a different type of riding. Probably a big 4T cruiser for that.

If I had a 5 mile race through trees and x- country, I would be on the 300. It is super aggressive and fast on the ST.

 

[Rush44]

If I had a 5 mile race through trees and x- country, I would be on the 300. It is super aggressive and fast on the ST.

Sign me up for that race! That sounds sweet.

 

[mtn-doo]

A little "shake down" vid of testing. That 300 modded this way is crazy awesome! Faster than my 450 if you push it. I just ordered a new 300 from my local dealer. It has a couple finishing touches to be done, then going home to it's owner, "Lachoneus". On second thought, after sufficient testing "required", i'm thinking a delivery date about mid April???

http://www.youtube.com/watch?v=pC8bAh0JspA&feature=youtu.be

 

[dirt rider]

A little "shake down" vid of testing. That 300 modded this way is crazy awesome! Faster than my 450 if you push it. I just ordered a new 300 from my local dealer. It has a couple finishing touches to be done, then going home to it's owner, "Lachoneus". On second thought, after sufficient testing "required", i'm thinking a delivery date about mid April???

http://www.youtube.com/watch?v=pC8bAh0JspA&feature=youtu.be

In the back of mind, I've thought that the 300 would be an excellent bike for a Mountain Horse kit and now after riding one, my thoughts are confirmed. The 300 flat rips and the light weight is instantly noticeable. You can't be lazy on it though, it is a bike that begs to be ridden and aggressive riders will love it. My 500 LT had trouble keeping up in the trees. Well done Randy!

 

[mtn-doo]

Thanks Steve, great testing day. We will need one more. Custom graphics just arrived, new UFO plastics, and the 38MM Smart Carb any day now. We will put together a good 300 vid that day... thanks again

 

[dirt rider]

Sounds great. Just let me know and I'm in!

 

[dirt rider]

So here are my thoughts on the 300......

As soon as you jump on the bike, you instantly feel how light and nimble it is. It turns really quick and stays up on top of the snow in the deep powder. Granted this bike has some well executed mods to add power and acceleration, but it all works. In the trees, the bike would accelerate faster than the 500 I was on and would carry the ski easier. We didn't have any wide open faces to see which would climb better in a straight up climb, but we will.

A four stroke is easier to ride and you can be a little lazy on one and still get around. The 300 doesn't have a lot of bottom end torque and must be kept in the sweet spot. For me, that comes natural as I'm a long time 300 rider, but in that sweet spot, the bike pulls hard and picks up track speed very fast. It's easy to do by feathering the clutch, but something I thought I should mention.

Even though the bike still has the stock carb, it started instantly every time and never sputtered once. We didn't ride a full day so fuel mileage is unknown as of now but didn't seem to use any more fuel than the 500.

I think this is a good project to consider as there are a lot of 300 KTM's (and other two strokes) sitting in garages that could be a viable option for snowbiking. The other plus is that modifying a two stroke is MUCH cheaper and easier than a four stroke.

 

[sullcat]

+1.....
a lot of times 2 vs 4 is rider preference.....I prefer 2
...The 300's work well with a little set up....

Brewster West put a SX kit on a 150 xc.... we dialed in a billet 36mm smart carb....the little thing rips good... I think gearing is a little short but need to get to the hills to test...

there's nothing like the sound of a group of "angry wasps" !!

 

[mtn-doo]

Hey guys,
Here are some pic's of some of the custom little etra's that add up to an overall better day out riding. #1- First is the air box memory wire cage we discussed earlier. I have found that spring cage, box bottom removed, proper venting, OEM intake boot un-altered provides the best engine performance and a "clean" box and filter. All day in the pow on the SXF and proved consistent with the 300XC as well. Abundance of air = HP and over-rev.
#2- The snow "roost" gaurd wider and longer than the little dirt one block snow from blowing forward under the air box. Also, it is made of neoprene rubber and will bend forward under the box when under "roost pressure".
#3- The rear engine guard. It is wide, from the chain to pipe wide across and formed to mold against the contours of the air box. It is also custom fit on the bottom to drop below the swing arm bolt completely stopping any snow from being thrown forward against the case and rear of the engine. It sits forward of the rubber roost flap.

All the little things add up to a better end package. The engine, carb or throttle body, and rear case stay clean. Warmer case, clean intake. Increases performance and provides a better, trouble free day.

 

[Jon Mutiger]

When considering the smart carb on a 2T, why wouldn't you go with the biggest one you can?

Jon

 

[mtn-doo]

When considering the smart carb on a 2T, why wouldn't you go with the biggest one you can?

Jon

Good question. When you "over carb" an engine you loose all low and mid range. Volume is increased and velocity decreases, thus signal decreases. That is why you will see a PWK series in a 36MM on a low/mid built engine. It produces tremendouse velocity at the crack of the throttle but lacks volume, and a 38/39MM on the same engine that is a mid/top engine. A 36MM has tremendous velocity at just the crack of the throttle. Amazing hole-shot and low end acceleration but not enough volume for WOT horsepower. It is a balance between velocity and volume. The apex of those two curves is the ideal carb for that specific engine.

 

[mtn-doo]

The arrival of the Cast 38MM Smart Carb kicked the last few details into high gear.

 

[mtn-doo]

Wiring for the Carb Heater complete and the temp sensor located under the seat. Instalation complete. Carb jacket next

 

[mtn-doo]

A good Carb Jacket takes a ton of time. I used Neoprene rubber, Heavy duty snaps in the corners and Velcro seams. Done and a nice tight fit. That completes the Carb system.

Custom Graphics and new plastics installed, Carbon Fiber Pipe Guard installed and after three returns!, found hand guards and shields that are acceptable. Time for a final test and tune run, then It goes home to it's very excited owner.

I will post the finished photo's and a tuning vid.

 

[Hooterville]

Heater installation

I am waiting for my cast carb to arrive and was hoping for a bit more info on the installation of the heater. Did Corey include details on where to drill and tap the hole?

 

[mtn-doo]

The cast version does not have a bossed area like the billet version does. The probe is located in the bell of the intake. Corey has to modify the probe to insure proper fit. He will send it to you drilled if you ask. It is in a small and very thin area. Very critical limitations. No room for error.

 

[mtn-doo]

Well, the Smart Carb testing is going well. This is by far the fastest, tree banging, boondocker I have ridden to date.... amazing bike, and haven't even pushed it... yet

http://www.youtube.com/watch?v=YK1m2wbGLZU&feature=youtu.be

 

[summitboy]

Randy, video says private ?

 

[mtn-doo]

Public now... sorry

 

[MTN AIR]

I rode a snowbike last week at my cabin in CO... Loved it...

Now I want to get one.

Thinking about a new 300 but I'm not a great dirt bike rider.. I have a 350xcf that I ride in the summer. Most 2 strokes are a little revvy for me. My theory(that I hope you guys have some opinions on) is a 300 with a Rekluse can be ridden slow too?

I would want this for summer as well..

Let me know your thoughts on this one.
Thanks