yz300 woods / snowbike build

dirtrebel · Aug 7, 2014

Hey guys my first snowbike was an old yz 250 2 stroke, ran it for one season and then went wr450, and then yz450, now I'm ready to go back to smokers. I still like the 4 strokes for their ease of use and cold temperature performance, but the maintenance is a pain and expensive. Ever since becoming a die hard snowbiker I have also been enjoying alot of summer riding, and I have found that a big 450 race bike is really just too much power and weight for me to handle on the high altitude "goat" trails of southwest Montana. Ive been looking to get a "woods" bike now for some time and was very close to getting a beta 300, ktm 300 or gas gas 300. For me though I really like bikes that can pull "double duty" as a woods bike and snowbike. This narrowed it down to the ktm 300xc pretty much as the only choice, but I am really more of a yamaha guy. I wanted to make sure I got a bike that I could handle in the woods and that would also be great on snow. so wide ratio and heavy flywheel / enduro tuning were out. electric start for summer is not mandatory for me if the bike is a 2 stroke. So after almost pulling the trigger on the orange I thought I should take a look at the good old yz250 one more time. I happened to see something that really caught my eye! Its a 2013 yz250 that was bought brand new and then the owner installed pretty much everything under the sun to make it a rip snorting crazy race bike! The owner decided he did not like the 2 stroke. Lets just say I got it for less than a new stock yz250.

Athena 300 big bore with Eric Gorr porting and extra piston and gasket set.
Rekluse core exp 3.0, heavy pressure plate springs and medium.
gytr billet clutch basket
steahly flywheel weight
cv4 silicone hoses
hammerhead levers (rear brake and gear shift)
fmf fatty pipe with shorty silencer, powercore 2 silencer and turbine core spark arrestor silencer.
v force 3 reeds
Bored carb with some insert thingy in it
xtrig spring preload adjuster
sprung for 230 lb rider (great fork springs for snowbiking)
applied upper triple
4 unused air filters
jd jetting kit
billet plugs and adjuster blocks
tm designs skidplate
guts racing gripper bump seat
get wireless hr meter (6.5 hrs when I got the bike!)
all stock parts included!

So i got it, just too good of a deal to pass up, rode it once and felt like I was on a rocket! So i decided to unbuild it! Yep that's right, I put it all back to stock! 250 topend back on, so now I have the pristine 300 topend and pipe for snow and a nice tame lightweight 2 stroke for summer woods! I put the stock springs back in it, forks and rear, removed rekluse as I dont really like it, it makes me forget to use the clutch and screws me all up, but for snow it might be cool. Stock pipe back on to tame it more, rejetted carb, added some cycra center reach mount busters and a hyde racing pipe guard and skidplate in one. Flatland radiator guards. Trail tech tto temp gauge. Put on an 18" rear wheel I had for my 450 and an IRC m5b tire, and a black front wheel from my 450. Added a pro moto billet kickstand and away we go! Took it on a 74 mile deep woods ride from taylor fork thru cabin creek to hebgen lake and back thru red canyon and the thing is sick! so lightweight and managebale! I will be remodding it for winter and snow and running a longtrack on it! I might run my 450 on colder days as it is -20 alot around here, but we will see. I will be doing carb heat and maybe a smart carb not sure yet, I really hate to spend any more money but don't want to be penny wise pound foolish at the end of the day. I will update here and there as snow approaches!

Wheel House Motorsports · Aug 7, 2014

dirtrebel said:
Hey guys my first snowbike was an old yz 250 2 stroke, ran it for one season and then went wr450, and then yz450, now I'm ready to go back to smokers. I still like the 4 strokes for their ease of use and cold temperature performance, but the maintenance is a pain and expensive. Ever since becoming a die hard snowbiker I have also been enjoying alot of summer riding, and I have found that a big 450 race bike is really just too much power and weight for me to handle on the high altitude "goat" trails of southwest Montana. Ive been looking to get a "woods" bike now for some time and was very close to getting a beta 300, ktm 300 or gas gas 300. For me though I really like bikes that can pull "double duty" as a woods bike and snowbike. This narrowed it down to the ktm 300xc pretty much as the only choice, but I am really more of a yamaha guy. I wanted to make sure I got a bike that I could handle in the woods and that would also be great on snow. so wide ratio and heavy flywheel / enduro tuning were out. electric start for summer is not mandatory for me if the bike is a 2 stroke. So after almost pulling the trigger on the orange I thought I should take a look at the good old yz250 one more time. I happened to see something that really caught my eye! Its a 2013 yz250 that was bought brand new and then the owner installed pretty much everything under the sun to make it a rip snorting crazy race bike! The owner decided he did not like the 2 stroke. Lets just say I got it for less than a new stock yz250.

Athena 300 big bore with Eric Gorr porting and extra piston and gasket set.
Rekluse core exp 3.0, heavy pressure plate springs and medium.
gytr billet clutch basket
steahly flywheel weight
cv4 silicone hoses
hammerhead levers (rear brake and gear shift)
fmf fatty pipe with shorty silencer, powercore 2 silencer and turbine core spark arrestor silencer.
v force 3 reeds
Bored carb with some insert thingy in it
xtrig spring preload adjuster
sprung for 230 lb rider (great fork springs for snowbiking)
applied upper triple
4 unused air filters
jd jetting kit
billet plugs and adjuster blocks
tm designs skidplate
guts racing gripper bump seat
get wireless hr meter (6.5 hrs when I got the bike!)
all stock parts included!

So i got it, just too good of a deal to pass up, rode it once and felt like I was on a rocket! So i decided to unbuild it! Yep that's right, I put it all back to stock! So now I have the 300 topend and pipe for snow and a nice tame lightweight 2 stroke for summer woods! I put the stock springs back in it, forks and rear, removed rekluse as I dont really like it, it makes me forget to use the clutch and screws me all up, but for snow it might be cool. Stock pipe back on to tame it more, rejetted carb, added some cycra center reach mount busters and a hyde racing pipe guard and skidplate in one. Flatland radiator guards. Trail tech tto temp gauge. Put on an 18" rear wheel I had for my 450 and an IRC m5b tire, and a black front wheel from my 450. Added a pro moto billet kickstand and away we go! Took it on a 74 mile deep woods ride from taylor fork thru cabin creek to hebgen lake and back thru red canyon and the thing is sick! so lightweight and managebale! I will be remodding it for winter and snow and running a longtrack on it! I might run my 450 on warmer days as it is -20 alot around here, but we will see. I will be doing carb heat and maybe a smart carb not sure yet, I really hate to spend any more money but don't want to be penny wise pound foolish at the end of the day. I will update here and there as snow approaches!

its dumb what people will throw at bikes and give away for less then oem price if they dont like it. good find, i wanna go rip that thing with wheels. ive been on the 450 train but my buddy has been shredding the yz250 lately and man is it light a nimble in the woods!!

Rush44 · Aug 7, 2014

Good build man. Keep us updated. Right now I'm in the same boat. I love the 450 for the winter but it's just too much for the tight single track. I'm looking at a 300xcw or new te300 for a dedicated woods slayer that could also do double duty as a snowbike once spring comes around. I'm also thinking about getting involved in the local XC circuit and doing the summer Hare Scrambles they put on. The 450sxf just isn't the bike for it.

Looks killer man.

Draxxus · Aug 8, 2014

Keep us posted on the build , sounds sick

wwillf01 · Aug 8, 2014

dirtrebel said:
Hey guys my first snowbike was an old yz 250 2 stroke, ran it for one season and then went wr450, and then yz450, now I'm ready to go back to smokers. I still like the 4 strokes for their ease of use and cold temperature performance, but the maintenance is a pain and expensive. Ever since becoming a die hard snowbiker I have also been enjoying alot of summer riding, and I have found that a big 450 race bike is really just too much power and weight for me to handle on the high altitude "goat" trails of southwest Montana. Ive been looking to get a "woods" bike now for some time and was very close to getting a beta 300, ktm 300 or gas gas 300. For me though I really like bikes that can pull "double duty" as a woods bike and snowbike. This narrowed it down to the ktm 300xc pretty much as the only choice, but I am really more of a yamaha guy. I wanted to make sure I got a bike that I could handle in the woods and that would also be great on snow. so wide ratio and heavy flywheel / enduro tuning were out. electric start for summer is not mandatory for me if the bike is a 2 stroke. So after almost pulling the trigger on the orange I thought I should take a look at the good old yz250 one more time. I happened to see something that really caught my eye! Its a 2013 yz250 that was bought brand new and then the owner installed pretty much everything under the sun to make it a rip snorting crazy race bike! The owner decided he did not like the 2 stroke. Lets just say I got it for less than a new stock yz250.

Athena 300 big bore with Eric Gorr porting and extra piston and gasket set.
Rekluse core exp 3.0, heavy pressure plate springs and medium.
gytr billet clutch basket
steahly flywheel weight
cv4 silicone hoses
hammerhead levers (rear brake and gear shift)
fmf fatty pipe with shorty silencer, powercore 2 silencer and turbine core spark arrestor silencer.
v force 3 reeds
Bored carb with some insert thingy in it
xtrig spring preload adjuster
sprung for 230 lb rider (great fork springs for snowbiking)
applied upper triple
4 unused air filters
jd jetting kit
billet plugs and adjuster blocks
tm designs skidplate
guts racing gripper bump seat
get wireless hr meter (6.5 hrs when I got the bike!)
all stock parts included!

So i got it, just too good of a deal to pass up, rode it once and felt like I was on a rocket! So i decided to unbuild it! Yep that's right, I put it all back to stock! 250 topend back on, so now I have the pristine 300 topend and pipe for snow and a nice tame lightweight 2 stroke for summer woods! I put the stock springs back in it, forks and rear, removed rekluse as I dont really like it, it makes me forget to use the clutch and screws me all up, but for snow it might be cool. Stock pipe back on to tame it more, rejetted carb, added some cycra center reach mount busters and a hyde racing pipe guard and skidplate in one. Flatland radiator guards. Trail tech tto temp gauge. Put on an 18" rear wheel I had for my 450 and an IRC m5b tire, and a black front wheel from my 450. Added a pro moto billet kickstand and away we go! Took it on a 74 mile deep woods ride from taylor fork thru cabin creek to hebgen lake and back thru red canyon and the thing is sick! so lightweight and managebale! I will be remodding it for winter and snow and running a longtrack on it! I might run my 450 on colder days as it is -20 alot around here, but we will see. I will be doing carb heat and maybe a smart carb not sure yet, I really hate to spend any more money but don't want to be penny wise pound foolish at the end of the day. I will update here and there as snow approaches!

That is a great find... That should push some good hp...

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mnsnowhawk · Aug 8, 2014

Damn rebel. You have too much fun with all your bikes. I need to get back out there this year. Hopefully work stays busy. Nice find on the bike. The ever evolving sport that we love. So much fun.

mxracer299 · Aug 12, 2014

I saw that bike on CL a while back, that was a steal! I did the same thing, picked up a Ktm 250 xc for summer riding and have a modded 300 cylinder for winter, should be the best of both worlds with just a cylinder swap! You just cant beat a 2 stroke for MT trail riding, I did a wr 450 and ktm xc 450 for the last 2 years, I just dont know who said 4 strokes are better...they need to be slapped! Haha I need to get down to the Gallatin before summers over, where can you ride motos by Hebgen, im going to be there this weekend mtn biking Mile to Sheep and maybe Lionshead but wouldn't mind bringing together moto down for a ride as well.

dirtrebel · Aug 12, 2014

mxracer299 said:
I saw that bike on CL a while back, that was a steal! I did the same thing, picked up a Ktm 250 xc for summer riding and have a modded 300 cylinder for winter, should be the best of both worlds with just a cylinder swap! You just cant beat a 2 stroke for MT trail riding, I did a wr 450 and ktm xc 450 for the last 2 years, I just dont know who said 4 strokes are better...they need to be slapped! Haha I need to get down to the Gallatin before summers over, where can you ride motos by Hebgen, im going to be there this weekend mtn biking Mile to Sheep and maybe Lionshead but wouldn't mind bringing together moto down for a ride as well.

you can ride motorcycles in the backountry on the north side of the lake. kirkwood, red canyon or tepee. up red canyon into cabin creek and then down kirkwood is awesome! Trail 205 and 210. either turn around at the bottom of kirkwood and go back or ride the highway back to your truck at red canyon. Also, you can take trail 206 (cabin creek divide) and go into carrot basin and towards pika point if u want more miles, eventually u will want to turn around. There is a gas station just east of the kirkwood trailhead, when u pop out on the highway. Here's a link to the motor use map. I'm stoked to be back on the 2 strokes!

http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3798791.pdf

tomk · Aug 13, 2014

mxracer299 said:
I saw that bike on CL a while back, that was a steal! I did the same thing, picked up a Ktm 250 xc for summer riding and have a modded 300 cylinder for winter, should be the best of both worlds with just a cylinder swap! You just cant beat a 2 stroke for MT trail riding, I did a wr 450 and ktm xc 450 for the last 2 years, I just dont know who said 4 strokes are better...they need to be slapped! Haha I need to get down to the Gallatin before summers over, where can you ride motos by Hebgen, im going to be there this weekend mtn biking Mile to Sheep and maybe Lionshead but wouldn't mind bringing together moto down for a ride as well.

if you ride up watkins creek, I lost a Gopro up there, somewhere between the end of the first open field and the trail Y that goes to Cofin Lakes or to Lions head! Off to the right of the trail:face-icon-small-hap

dirtrebel · Nov 4, 2014

snowbike install

Put it all back and made it a snowbike. This is my warm day tree banger bike, my primary ride will be a 2012 yz450 4stroke with long track. It got alot of hours on it last year so I figured I would build this as a backup to tinker with.

I'm gonna let the pictures do most of the talking, I'm sorry they are sideways.
1. bring it in and strip it.
2. reinstall .54 fork springs and new seals.
3. bring in a 2014 st kit. (thanks mx racer)
4. reinstall athena 300cc topend
5. install thermostat, temp sensor and carb heater plumbing.

dirtrebel · Nov 4, 2014

continued

6. install bearing upgrade kit into 2014 st.
7. install smart carb with heat collar and prepare stock carb with a heat collar.
8. remove bottom of airbox and install pod filter setup
9. button everything up and fire it up for a few heat cycles, then retourque head and base bolts.

Before first ride:
install pipe guard, rekluse core exp 3.0 with heavy wedges pressure plate springs and exp ring springs. and reinstall stock flywheel. Build carb jacket.

Draxxus · Nov 4, 2014

Nice build give some ride reports later if you can especially in comparison to other builds if you can

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n16ht5 · Nov 5, 2014

I'm dying to know if you are going to sell the YZF and just run the YZ in the end... I wonder how the HP numbers compare?

dirtrebel · Nov 5, 2014

n16ht5 said:
I'm dying to know if you are going to sell the YZF and just run the YZ in the end... I wonder how the HP numbers compare?

I'm dying to know as well! As you know I am really partial to the 4 stroke, until it shells that is. Around here we get alot of below zero temps and deep "cold smoke" powder so the grip heaters and headlight is nice on the fi yzf. Plus my yzf is pretty "hot" with the gytr high comp piston and gytr cams. Also I have always run longtracks and the 4 stroke is the go to bike for longs, I don't know if the 300 would excell with a long. Someone else on here said something about when the two stroke bogs a little and falls off pipe you suffer while the 4 strokes tractor right on by. I hate the front intake on the yzf though, it clogs seemingly no matter what (ive tried it all) and if you open it up it looks terrible and will deafen you. My next 4 stroke might have to be a hopped up wr450f (rear intake on the wr) I think both 2's and 4's have pluses and minuses, with such variable conditions we have here I see both bikes getting ridden alot! I cant wait to go into "battle" on this lightweight smoker!

dirtrebel · Nov 5, 2014

n16ht5 said:
I wonder how the HP numbers compare?

claim of 53-57 with the 300 kit.

dirtrebel · Nov 5, 2014

Draxxus said:
Nice build give some ride reports later if you can especially in comparison to other builds if you can

Sent from my iPhone using Tapatalk

will do, as soon as we get some snow I plan to try both carbs back to back and see if this whole ignition mapping thing is an issue or not. I really want to feel the difference in the 2d map and 3d map on snow where I can actually run her wide open under load. For those of you who may have missed it when you put a smart carb on a yz250 you remove the throttle position sensor because it is integrated into the stock carb. when you do this the cdi revrts back to 2d ignition mapping. some claim no difference others claim big difference. I could not tell a huge difference on dirt, because I am not an aggresive rider. Although it did seem a little less "snappy" a good thing for me on dirt, lol. I can swap carbs in about 10 minutes if I'm not all shrouded and jacketed for testing purposes.

CATSLEDMAN1 · Nov 5, 2014

old blue's

this will be my 4th year on my wr450. last year I built a yz250 sno bike, fooled with it a bunch early season, then parked it when I got tooo busy riding.
Long track on both bikes. So going to be interesting to see how you like your blown out 250. A better carb than stock will help for sure.

dirtrebel · Nov 6, 2014

does anybody have an opinion on cast vs forged piston on these 2 strokes? This big bore piston is a forged unit. Years back with the polaris triples and other sled engines I was warned to steer clear of forged (wiseco, etc). I was advised that in a snow application forged was dangerous because of the rapid cool off of the engine when stopped for lunch, stuck, etc. I will obviously be aware and do good full warm ups, but its hard when you take a short break and the engine cools all the way off. 2 strokes take forever to warm up fully at an idle or high idle so its easy to jump the gun and braaap of right into a cold seize. The bypass thermo will help blend the warm coolant with the cold and speed warm up. I never had any prolems with the yz250 on snow a couple years ago with its stock cast piston. Is a forged piston more dangerous than a cast under rapid heating and cooling scenarios?

tomk · Nov 6, 2014

dirtrebel said:
I'm dying to know as well! As you know I am really partial to the 4 stroke, until it shells that is. Around here we get alot of below zero temps and deep "cold smoke" powder so the grip heaters and headlight is nice on the fi yzf. Plus my yzf is pretty "hot" with the gytr high comp piston and gytr cams. Also I have always run longtracks and the 4 stroke is the go to bike for longs, I don't know if the 300 would excell with a long. Someone else on here said something about when the two stroke bogs a little and falls off pipe you suffer while the 4 strokes tractor right on by. I hate the front intake on the yzf though, it clogs seemingly no matter what (ive tried it all) and if you open it up it looks terrible and will deafen you. My next 4 stroke might have to be a hopped up wr450f (rear intake on the wr) I think both 2's and 4's have pluses and minuses, with such variable conditions we have here I see both bikes getting ridden alot! I cant wait to go into "battle" on this lightweight smoker!

found a solution for lights and heated grips, not enough watts to run both at the same time, but you could have both wired in and use what you need more when u need it!

http://www.steahlyoffroad.com/light...oils/yamaha-yz-250-99-09-lighting-stator.html

no reason not to run a smoker 100% now, sell the heavy turd and buy another smoker!! braaaaAAAAAAPPPPPP:becky:
^
(thats the powerband kickin in) :face-icon-small-win

dirtrebel · Nov 6, 2014

:face-icon-small-win

tomk said:
found a solution for lights and heated grips, not enough watts to run both at the same time, but you could have both wired in and use what you need more when u need it!

http://www.steahlyoffroad.com/light...oils/yamaha-yz-250-99-09-lighting-stator.html

no reason not to run a smoker 100% now, sell the heavy turd and buy another smoker!! braaaaAAAAAAPPPPPP:becky:
^
(thats the powerband kickin in) :face-icon-small-win

I know I know, mo money, but worth it if it isn't a piece of crap that leaves me with no spark. When you fly out a couple times this year you can ride the smoker, but I'll have to keep you cold and in the dark so you don't braaaap on by!

also I think my heavy turd was well ahead when I rode your kx500 and you rode it!:face-icon-small-win

yz300 woods / snowbike build

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