The Ultimate 300 Build Thread - 2014

mtn-doo · Sep 18, 2014

Going to install the 38MM Billet Smart Carb. Before the carb goes on, I am going to install the carb heat collar. I put the carb in the freezer for 6 hours. Next I prepped the collar by removing the plug and both barbed fittings. I lay the heat collar flat on top of a bench vise. With a butane torch I gently heat the outer corners of the heat collar until just "hot to the touch". Heating the outer edges pulls the inner radius outward a few thousandths. I then take the carb out of the freezer and lay it flat on the bench. With leather gloves, I index the collar in the position I want without touching the carb. Just hovering over it. When my alignment is where I want it, I push the collar into place and let everything cool for a few minutes.

The carb install is super easy. The one thing to remember is to pull the choke knob up before you turn your gas on. The carb is sealed and needs to vent the air out of the float bowl through the choke circuit as it fills.

mtn-doo · Sep 18, 2014

Next the carb goes into place. There are a couple needed items to make everything fit properly. One is the intake boot. I recommend the 2013/2014 300 "XCW" boot. They are a straighter intake shot and have enough room to trim 1" of length off to compensate for the added length of the carb. Simple measure and mark 1" back from the carb attachment end and make a clean cut removing 1". The fit is perfect.

mtn-doo · Sep 18, 2014

The last part of the carb install is the throttle cable. I feel this is also a "must do" item. With bar risers and the added length of the carb, I recommend the Motion Pro, T3 - +4 cable. It is a super slick cable. They have an inner core that is amazingly slick and smooth. Perfect for our frozen, icy conditions. It is also 4" longer making routing it and fitment super nice. The must important benefit is the cable is threaded the same as the carb cap. You thread the cable into the carb cap and lock with a lock nut. No slack or free-play. And "safe". I install this on ALL bike projects regardless of make or model. The Service KX500AF had the old "brass bushing" style cable end. They are loose and can bounce out of the carb top and hold your slide open. This is a must do.

Sickness · Sep 19, 2014

oops I did it again

HI Randy,
I was hoping you could answer a few questions for me...

I have a 2104 XC, I bought a 2014 SX cdi box, how does that affect the engine as opposed to the '12 and earlier? Should I return it and just keep the stock '14 XC box?

Is that a new airbox mod with the '13/14 XCW boot? I was already off and running with the 45 degree 2.5 into 3". Does the boot get finished off with a standard filter? No more cutting out the airbox?

What was it you said about the Smartcarb metering rods and snowbiking?

Can I use the ProCircuit Plat2 with the stock silencer? I know I can, but I guess the q is how much does the PC silencer add to the fun?

Once again, thanks for sharing this info with all of us!

mtn-doo · Sep 21, 2014

The 2014 XC CDI Box feels pretty good. Comes on real quick and early. I need to see if it shut's off on top or not? If it over-rev's , it will be a great box. I want some time with it though. I have both and will swap them around and get an opinion. The 07 through 2012, 250 SX CDI is the most aggressive. 2013 is de-tuned.

Great boot and box news. I worked with Cycle Playground on making a boot for the Smart Carb and heater combo. Received the first proto type last week. It is excellent. You can order from them. Ask for Michael at 570-954-1565. The do it yourself method is get a 2013 or 2014 "XCW" boot and cut off 1". Fits perfect. Cycle playground makes an inner molded lip for the boot carb transition. Yes on cutting out the bottom of your box. Either stock or pod, you need to cut out the bottom. Open everything up. No place to trap snow and works better than anything else we have experimented with. The box is only $38 from KTM World. You then have a winter box and a summer box. Swap when you swap your kit and tires. Keep both boxes complete with boots and filters. Super slick with two set-ups. No mod's to deal with.

The Smart Carb delivers fuel based on the size of the metering rod. Stock is usually perfect. However, if you are a little rich or lean, you simple change the rod. Don't plan on it and make this confusing or a hassle. The stock rod is perfect for 99% of the bikes.

You're very welcome! My goal in these projects is to help find solutions for the thousands of bikes out there wanting to get on the snow, and give the confidence to buy a Timbersled Mountain Horse Kit. If you're sitting on the fence with a traditional Carb or Icing issues, jump off the fence! The solutions are here for you to have a long, fun, trouble free season in the snow. This project is designed to inspire the thousands of 250/300 class bike owners to join the fun with confidence!

the gman · Sep 21, 2014

Also on a side note make sure you can install your fittings after you slide your heater on the carb or you will cuss yourself. I installed the fitting and the plug first. Sure is a nice set- up randy.... Thanks...any word on a universal blanket for the carb yet

mtn-doo · Sep 21, 2014

the gman said:
Also on a side note make sure you can install your fittings after you slide your heater on the carb or you will cuss yourself. I installed the fitting and the plug first. Sure is a nice set- up randy.... Thanks...any word on a universal blanket for the carb yet

I have a universal neoprene boot that is super nice. No manufacturing party involved. I will post dimensions and pic's so people can make one. Very easy and a "must do item".

mtn-doo · Sep 22, 2014

Backing up a bit to show the mounting and wiring for the EGT. The number plate bolt is perfect. The gauge placement is front and center. There is a yellow single wire that is a "hot when running" wire. Will not drain your battery. I use this source for grip warmers as well. I put a "dab" of liquid electrical tape on the connector to protect it. That mounting bolt is a great place for your ground wire as well. "white wire from the gauge".

mtn-doo · Sep 24, 2014

About ready for the cylinder and new head. Then the pipe etc all goes back on. I thought I would help pipe temps a bit and avoid the smelly, hot carbon fiber from the pipe guard. I pulled apart a pipe from a snowmobile and removed the high temp fiberglass insulation. It is about 1/8" thick. I used a little spray adhesive and started cutting pieces to fit flush to the edges of the guard. This will be a nice little touch helping the guard last as well as holding some heat. The guard fit nice on the pipe. No changes and looks OEM. No insulation visible.

mtn-doo · Sep 24, 2014

The new Head and changeable domes from Slavens Racing are in. They have a larger dome diameter, a little higher compression and the option for a 6000 to 12000 foot elevation dome. Very nice product and the "bling" looks sharp also.

http://slavensracing.com/

Summitseeker · Sep 24, 2014

mtn-doo said:
The new Head and changeable domes from Slavens Racing are in. They have a larger dome diameter, a little higher compression and the option for a 6000 to 12000 foot elevation dome. Very nice product and the "bling" looks sharp also.

http://slavensracing.com/

I have mine already installed! LOVE it!

mtn-doo · Sep 25, 2014

With the cylinder, reed block, Smart Carb with heater and thermostat, and new head all back together, I can install the new pipe and a new plug.

The plug needs to drop from a 7 to an 8. The larger number is going down in heat. The larger number the cooler. The 7 is good for the original application however, when you advance timing and bump up compression you need to drop down one temp number on your plug. The timing advance of the SX cdi box raises cylinder temps as does the added compression. You will find with a modded 300 you will get some "pinging". This is caused by residual heat in the plug causing pre-ignition / detonation. Interesting point about plugs. The spark temp is all the same temp. You do not get a "hotter" or "cooler" spark. The flame is all the same temp. The difference is the temp of the plug itself while running. A "cooler" plug simply gets rid of heat in the plug quicker and a "hotter" plug stays hotter while running. When the plug is a little too hot, it acts like a "glow plug" in a diesel engine. It is glowing hot and ignites the fuel at random times other than when it is supposed to by the ignition. The fine wire plugs are also superior at dissipating heat, which is the big priority, but also quicker and more efficient with the SX box. The best plug I have ever used in the "8" heat range is the NGK BR8EIX, lot #5044. There are two lot numbers for that plug. It is very important to get it in lot #5044.

mtn-doo · Sep 30, 2014

To stay on track with this build, "quick and major FUN", I am ditching the OEM throttle for an "on/off" switch. The stock throttles all take a lot of twisting to get from zero to WOT. I like a bunch quick. Like a 160 HP sled gives you everything in 1 inch with your thumb. For the purpose of this bike, quick and fun in the trees, I am installing a 1/4 turn throttle. I call it an on/off switch. They are already stupid quick in the trees, this will only add to the fun!

http://www.g2ergo.com/store/2-stroke-quick-turn-system/

mtn-doo · Oct 1, 2014

Time for the new clutch. For this bike's purpose, the new Rekluse 3.0 will be super nice. I have used the Rekluse on other bikes and found it is not mandatory but makes transitions and technical, high speed riding easier and faster in some situations.

I spent some time on wheels tuning this clutch for my liking. I do not want the "idle engagement" like you would on a single track bike. I want a "snowmobile" type engagement. Perfect for a two stroke and boondocking. I want the engine to get above the "soft spot" and be building rev's as the clutch engages. Just like a snowmobile. I have it about right. I can adjust after some snow time. Where it is now; Rekluse 3.0, Heavy wedges for solid engagement, three optional "super heavy" EXP springs to delay engagement until rev's come off the bottom, and the 450F, 280 PSI Belleville spring for stack pressure. Zero slip. Simply replace the OEM belleville with the 280 over the EXP ring. The slave cylinder external adjustment is super nice for adjusting free-play gain. Super nice clutch.

The result is pretty cool. Idling in 2nd gear, whack the throttle and the RPM's jump above the bottom "soft spot" as the clutch engages. Result, front tire at 12 o'clock high and back tire boiling. Instantly

This should add to the ST quick/fun factor.

wwillf01 · Oct 1, 2014

mtn-doo said:
Time for the new clutch. For this bike's purpose, the new Rekluse 3.0 will be super nice. I have used the Rekluse on other bikes and found it is not mandatory but makes transitions and technical, high speed riding easier and faster in some situations.

I spent some time on wheels tuning this clutch for my liking. I do not want the "idle engagement" like you would on a single track bike. I want a "snowmobile" type engagement. Perfect for a two stroke and boondocking. I want the engine to get above the "soft spot" and be building rev's as the clutch engages. Just like a snowmobile. I have it about right. I can adjust after some snow time. Where it is now; Rekluse 3.0, Heavy wedges for solid engagement, three optional "super heavy" EXP springs to delay engagement until rev's come off the bottom, and the 450F, 280 PSI Belleville spring for stack pressure. Zero slip. Simply replace the OEM belleville with the 280 over the EXP ring. The slave cylinder external adjustment is super nice for adjusting free-play gain. Super nice clutch.

The result is pretty cool. Idling in 2nd gear, whack the throttle and the RPM's jump above the bottom "soft spot" as the clutch engages. Result, front tire at 12 o'clock high and back tire boiling. Instantly

This should add to the ST quick/fun factor.

I can tell you on my 300 and every Rekluse I have owned... we are up to about 5 bikes as a family z start, core 2, core exp 3... I love riding tight trails here is Utah..... high engagement with the hardest springs has always worked the best if you are an aggressive rider or not... it stalls less, engages better and is the best power delivery. . That is my 2 cents.

mtn-doo · Oct 16, 2014

Back to get a little done on the 300 project. It's been crazy busy.... Before I get into the air box and intake system, I want to knock out warmers and the Pro Moto goodies.

I like the Moose Racing warmers. Easy install and a small, clean rocker switch for high/low/off. The number plate screw works nice as a ground location. Also I recommend shrink tube or electrical tape over aluminum. Clutch side bar and the throttle tube if it's an after market aluminum. This will prevent shorting out and add longevity. For the grip, I like the super soft and thin Super Moto grip. It has a soft "gummy" feel and is thin. When you put heat under it, it is quick to warm up and soft. Very nice

mtn-doo · Oct 16, 2014

The Fastway parts are top shelf. Super nice. I ride a lot standing, so I prefer the 2" Billet riser. They have a dove-tail fit. Super nice. The hand guards attachment is solid and a handy/solid place to pull your bike around or even tie it down. I don't care for the large shields so I drill and tap for a smaller, low profile shield. The adventure pegs are a great, large platform for snow boots. They keep improving every year. They had gussets and supports that made the familiar "ice ball" that was a pain in the rear. I completely gut the supports, sand, then re-paint in a gloss black lacquer paint. On a company ride last year, the Fastway crew was with us. They were shocked to see the pegs I cut up but then realized the supports weren't really necessary for weight bearing. This year they come without gussets. There is still the center spar. They should be better but the "option" is to remove the center spar and finish with a little sanding and paint. They look OEM and never get a snow ball.

barefooter · Oct 16, 2014

It is like waiting for Xmas morning to arrive.

I would really like my bike please. :face-icon-small-hap

portgrinder · Oct 16, 2014

I'de run 9EIX plugs in a setup like this. extra insurance.

keep going up till you foul one at low rpm.

Motogeek33 · Oct 16, 2014

mtn-doo said:
They should be better but the "option" is to remove the center spar and finish with a little sanding and paint. They look OEM and never get a snow ball.

That's a great idea on the pegs. I haven't had enough trouble with ice build-up with my Fastways to overcome my reluctance to start hacking on my $225 pegs, but yours look so good that I'll definitely keep it in mind. Nice job!

The Ultimate 300 Build Thread - 2014

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