KTM300XC Build Project

[relentless rider]

Are you using the sx low elevation head or high? .I thought I herd a little destination going on so started mixing a splash of 110 and it went away.ive always been a believer in good fuel, and what comes out of the pumps anymore is crap

 

[CATSLEDMAN1]

gas

with gas prices coming down I'm concerned gas quality is coming down as fast, going to run some av gas in my yz250. Took my older hi compression yZ head and did a little mod to open the chamber lower compression for 2013 poooor gas.

Worked with pal this summer on 2013 300 KTM with head mods til electric start is now marginal in warm weather with 185 or so compression on our gauage...........so there seems a limit if you want the e start.

 

[mtn-doo]

with gas prices coming down I'm concerned gas quality is coming down as fast, going to run some av gas in my yz250. Took my older hi compression yZ head and did a little mod to open the chamber lower compression for 2013 poooor gas.

Worked with pal this summer on 2013 300 KTM with head mods til electric start is now marginal in warm weather with 185 or so compression on our gauage...........so there seems a limit if you want the e start.

Kick and hit the button at the same time. The kick gets it over the hump, then the button will keep it spinning. Very slick trick. Works perfect. Also a batt with 200+ CCA will turn 200psi in "warm weather". We will test and document cold starts. Heck, I'm not at all worried... Last season I started a 210PSI, KX500 every day with no e-start. It was usually started and warmed up before the other bikes. I'm not scared. Ha

 

[relentless rider]

And the 300 starts almost every time with one kick,

 

[mtn-doo]

Got the cylinder back. It's a thing of beauty! Basic port job. Better flow from both sides. Sub-exhaust ports widened a little. Everything shined up. From idle to wot, strong and smooth.

 

[mtn-doo]

After a basic port and polish and the SX head, my "target" comp was 180 psi. This put a smile on my face!

 

[mtn-doo]

Darn, the last post bumped to a new page. On the bottom of page 1 are the cylinder pic's. I meant to post them together.

 

[relentless rider]

Looking good! I'm going riding tomorrow ill let ya know how it goes.I ended up swoping the gears around to 20-17 in the MH as I was in 4 gear just around the .yard going slow.well see tomorrow if that works.ill be trying a few different gear combos.
12-17 17-20 was 12inchs roll out,
12-17 20-17 was 16 1/2 roll out.

 

[somepunk22]

What are you guys hitting for top speeds with stock gearing on the XCs?

 

[relentless rider]

What are you guys hitting for top speeds with stock gearing on the XCs?

Ill let you know tomorrow night

 

[thejean]

What are you guys hitting for top speeds with stock gearing on the XCs?

Good question. Never looked. Will do this winter.

 

[burnz]

this seems like a fairly high dollar build yes? what of the mods you are doing to the bike do you feel would be absolutely necessary to be able to run a track behind the 2-stroke and which wouldn't? very interested in this build kudos cant wait to see how it turns out

 

[mtn-doo]

this seems like a fairly high dollar build yes? what of the mods you are doing to the bike do you feel would be absolutely necessary to be able to run a track behind the 2-stroke and which wouldn't? very interested in this build kudos cant wait to see how it turns out

This is not a high dollar build. A basic 450F will cost you tipple in cost for equivalent mods. The basic "must do" list is fairly short and inexpensive. People need to realise they do not need a state-of-the-art bike to go every where and have the most fun on snow they've ever had. There are several factors to consider. "one bike, summer and winter"? only a dedicated "snow bike", to be the "hero" when you ride? etc... This build is for a guy who wants a super fun and capable snow bike AND an awesome summer bike. The 300 class 2 stroke, the 300XCW/XC specifically, is the #1 summer do all bike and the #1 winning cross country/enduro bike you can buy. That pretty well covers your all around summer bike. To prep it for snow, the basic "must do" list is fairly short and very inexpensive compared to a 4 stroke. A smart carb for BOTH summer and winter, a must do. $375. Intake mods for snow. Air box and intake $70 + $150 and you are ready to ride. No hassle, oil changes, tuners, etc... If you want the best built custom 300 it will cost more of course, depending on mod's and ergo items you prefer. All the custom goodies add up, but a no hassle good performing 2 stroke is the easiest and "no hassle", no maintenance, gas and go option.

 

[mtn-doo]

Looking good! I'm going riding tomorrow ill let ya know how it goes.I ended up swoping the gears around to 20-17 in the MH as I was in 4 gear just around the .yard going slow.well see tomorrow if that works.ill be trying a few different gear combos.
12-17 17-20 was 12inchs roll out,
12-17 20-17 was 16 1/2 roll out.

Try the 12/17, 16/17 great combo.

 

[relentless rider]

Very happy with the 300! 2 to 3 feet of powder with no base and the bike flat out rips, ran 5 gear on the flats, and 2 and 3 for most of my climbs,2 gear wot tthough nasty treed in side hills with the track just blowing off , pretty cool, dont be scared to rev the nuts out of it with the pipe singing ran it all day that way.
the 300 with a lighter person is a woods Slayer,
Didnt stop to miss with gearing happy for now with 12,17,20,17, but from heavier riders id probably lower gear .so thats my 2 cents .
Mtn doo ill try that gear combo as soon as I can have enough time to shut it down for a few. Lol

 

[mtn-doo]

Thermostat. I tried and tried to find a clean fit for the 70C thermostat. It is a no go. The length between the head and the nipple in the frame is so short and close there is no way to get the 4 pronged 70C to fit. The next option is the 55C KTM single in and out. It was a close fit but fits! Very clean and no modifications. With this being a 2 stroke, the 55C, 153 degree F, will be good. The 2 stroke loves cooler temps and no motor oil and valve train to worry about. The 55C has been the choice for ice racers and works well in the 2 stroke bikes.

 

[mtn-doo]

Finally received the pipe and silencer. Was waiting on the silencer. Installed and the P3 Carbon Fiber pipe guard came in yesterday. I will wait on installing it until the last minute.

 

[thejean]

Is a thermostat needed? My bike seems to run fine without an upgrade.

 

[summitboy]

Lol. I would of sent you my P3 pipe guard. I just threw my PC Platinum 2 in the garbage lol. Never again !

That P3 is nice stuff eh. Best pipe guard made in carbon bar none. Makes all others look like potato chips. Spendy though. Almost as much as a pipe

I think that stat is gonna be to cold in the deep stuff. Im bettin you will have a Bob in a 70C soon. Can u not use the housing from the XCW ? I know a 70 will fit the 55 housing from a 2010 300XCW.

 

[mpowyo]

yea this will be awesome to hear how it turns out. I ran My 08' 300 xc-w on my 2moto then my ts. Slavens head red spring and platinum 2 when I got the ts and It worked awesome but you do feel like you have to be spot on the jetting because of all the full throttle. Having to run 12 front sprocket was a pain and the airbox filling also a problem I still havent solved considering making some kind of snorkel. Having walked miles out from blown up sleds before made me kinda nervous. That said kinda wish I woulda stayed with it and tried a smart carb.. That bike crushed my 12' 500 xc-w untill about 65mph but the mods made it an animal in the tight stuff in dirt, white knucle fury! haha. Can not wait to hear more makes me wish I kept mine now sold it so cheap anyway.