250 Two Stroke Set Up

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8/30/2018 7:28 AM

Myself and others have mentioned before that we feel the 250 two stroke only really fits us in a very small window of track conditions, for me that is less jumpy or more of a "flowy" jump type of track, with deep loam or sand. I admit I probably only rode the 250T about 20 total times while I had one so I probably didn't give it a fair shake.

My question, if I were to get another YZ250T to compliment my 17 350SXF, does a FWW make a huge difference? My biggest qualm was definitely how sketchy I was over jumps. Felt front end high all the time, the first big jump I hit I almost looped her out...yeah, real squid stuff...but it scared the crap out of me.

I was thinking if I tamed the 14/52 to a 13/48 and a FWW it might make the bike a little less abrupt on jump faces. The 14/50 or even 51 wasn't fun for me. Maybe I'm just over thinking it. I don't ever remember feeling as sketchy on 125s regarding jumps and stuff but I've been off two strokes since 2004 except for a brief time in 2012/2013.

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8/30/2018 7:39 AM
Edited Date/Time: 8/30/2018 7:48 AM

Isn't going to 13/48 from 14/52 going to be more or less the same ratio as going up half a tooth in the rear (if going down one tooth in the front equals going up 3.5 teeth in the rear), which will have the opposite effect of what you want? The KTM 250 is highly tuneable. Flywheel weight, green spring, unplug the wire under the tank and you've got a tame but still powerful 2 stroke.

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Current rides: 2021 TM 144, 2008 YZ250

8/30/2018 7:46 AM
Edited Date/Time: 8/30/2018 7:48 AM

Why would you want to increase the rear sprocket tooth count to make less abrupt? Just lose usability and make it more abrupt, IMO anyway. I would go down a tooth or two. I think you just need more calculated seat time.

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vomiting equals disqualification.

8/30/2018 7:59 AM

Based on everything I've read about flywheel weights, it does sound like adding one would give you the benefits you're looking for. However, I'd make that your starting point, then you can play with gearing as needed. Never a good idea to change more than one variable at a time.

Out of curiosity - Did you have the sag/suspension "dialed in" on your old bike? The more I learn about suspension, the more I understand how significant even just a few mil's here and there can make a world of difference

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Positively, absolutely 110% obsessed with anything MOTO.

8/30/2018 8:08 AM

Flywheel weights are a great addition to most 250 smokers, I ran 9 oz on almost all of my YZ's and my SX. They will smooth out the hit and let you carry a bit more speed through corners.

I find that a 250 smoker is better for really jumpy tracks. Having less rotating mass is the 2 stroke advantage, sounds like you just aren't using good technique and are letting the hit of power put your weight back.

Focus on keeping your head over the bars and squeezing with legs at take off and you will see just how sweet it is to fly a smoker!

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8/30/2018 8:10 AM

I kind of a agree with the sentiment about the 'window" of use. They are much more fun on sand and tacky tracks than they would be on a dry hard packed track. This is my problem, I mostly ride on the latter, otherwise I think i'd be quick to go back to a 2 stroke again.

If I do again though I think I'm going to want the KTM XC250, something tells me they would put the power down just right in my conditions.

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17 KTM 450 SXF - AMAZING!

8/30/2018 8:13 AM

The 13/48 and 14/52 are really close but slightly different. The 14/52 was really snappy and was more of a on or off motor, which was fun but I found a little more hard to control. I was thinking the 13/48 wouldn't load up the shock as much.

Blake - Suspension was not set up and you're right it makes a huge difference in how the bike balances. Since I got my KTM set up its so much better.

From the stand point of jump technique my problem was I was leaving the gas on too long on the faces. I found that on tracks where the jumps are bigger and farther away from turns I could maintain speed easier and just carry that speed over, as opposed to being on the gas really hard up the face to clear a jump.

Calculated seat time was definitely lacking on the last two stroke I owned and would probably lend to a lot better of an experience.

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8/30/2018 8:14 AM

Leaning forward off jumps will keep the front from going high

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8/30/2018 8:17 AM

TJMX947 wrote:

The 13/48 and 14/52 are really close but slightly different. The 14/52 was really snappy and was more of a on or off motor, ...more

Sounds like you've figured out your own issue tongue

get the smoker dude! Best decision I made was getting rid of my 450 for my yz250

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

8/30/2018 8:27 AM

I never do flywheel weights or anything like that on mine. I do find with the combo of getting tired and the track getting rougher I tend to slide back on the seat too much and end up slamming the brake pedal in the air to keep the front down. With proper technique and throttle control you'll figure out the jumping just fine. I liked the stock yz gearing for most tracks personally.

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8/30/2018 8:29 AM

seth505 wrote:

I never do flywheel weights or anything like that on mine. I do find with the combo of getting tired and the track getting ...more

x2 on this. Keep my bikes stock with gearing, and motor. Pipes will be changed when I can afford it, but no FWW or anything like that. The YZ250 is such a solid package.

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

8/30/2018 8:48 AM

TJMX947 wrote:

Myself and others have mentioned before that we feel the 250 two stroke only really fits us in a very small window of track ...more

Honestly, having grown up on 2 strokes I feel safer jumping a 2 stroke and prefer them on a Supercross style of a track where you can flick the bike around and put it where you want it to go. I always felt 4 strokes gave the illusion that they "feel" safer and connected to the ground but that illusion is/was just that...an illusion and people tend to ride them over their heads and when things go sideways (literally) its much worse with physical injuries as compared to a 2 stroke.....typically this happens bec with the rotating mass of the overhead cams and the height within the frame and weight of the 4 stroke head as compared to a 2 stroke head which sits much lower and is MUCH lighter.

However, in a tight jump pack rhythm setting they were always too slow and cumbersome of a bike to enjoy that type of riding and 4 strokes may go straighter with much more ease but when they get out of shape to the point you know they are off kilter, its almost too late most times.

Thats my take on the 2 stroke, plus a 2 stroke will only let you go as fast as your talent will allow you to go.

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8/30/2018 8:53 AM

'16 YZ250, 14/51, small fww (not really needed lol), stock timing, stock pipe, FMF shorty. Super happy with it.

Initially I went with a heavy fww, and retarded timing as I was just coming off of a 450f, and afraid of the snap. Once I was used to it, that motor set up became just plain lazy.

Riding a two stroke is all about momentum, imo. You just can't power over stuff like a big 4s.

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8/30/2018 8:59 AM

Lightning78 wrote:

Honestly, having grown up on 2 strokes I feel safer jumping a 2 stroke and prefer them on a Supercross style of a track where ...more

I 100% agree with you. I am more willing to jump something out of my skill level because of the illusion of comfort the four stroke grants me, and like you said once the four stroke gets pointed out of a straight line you're basically holding on for the ride.

I was riding Sunday and honestly I just kind of felt bored, like I can take it or leave it. I told my wife that my feelings toward riding right now don't justify a 9k+ bike. We'll see what the next few months or year unfolds, in all honesty I think I would enjoy a 125 as much as a 250 if my weight were in check.

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8/30/2018 9:17 AM

I ran the GYTR FWW on two different YZ’s and couldn’t tell a difference both on a full blown race motor and a stock motor.

The YZ250’s don’t take much. You can play with the timing, but for me the stock motor setup is so dang good, it’s hard to beat. Maybe an extra tooth on the rear if you’re fast enough to carry speed to stay in 3rd, Run 50/50 pump and race fuel. Stock pipe is where it’s at. Don’t waste your money unless you damage to stocker.

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8/30/2018 9:22 AM

TJMX947 wrote:

Myself and others have mentioned before that we feel the 250 two stroke only really fits us in a very small window of track ...more

Lightning78 wrote:

Honestly, having grown up on 2 strokes I feel safer jumping a 2 stroke and prefer them on a Supercross style of a track where ...more

TJMX947 wrote:

I 100% agree with you. I am more willing to jump something out of my skill level because of the illusion of comfort the four ...more

Honestly dude, I had that same feeling when I had my 450. It was still fun, but it wasn't like I wanted to keep spinning laps. I was just done after 2 15 minute motos.

Once I got the 250 it brought back the fun and both times I've ridden it, the spark was there again and I put in 3 20 minute motos. That bike is so much fun to ride!

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

8/30/2018 9:46 AM

TJMX947 wrote:

The 13/48 and 14/52 are really close but slightly different. The 14/52 was really snappy and was more of a on or off motor, ...more

I think you may have your ratios slightly mixed up. A 14/52 gives you a 3.71:1 ratio, while a 13/48 gives you a 3.69:1 ratio. Both are VERY similar. So close you would most likely not be able to feel it. For example the difference between a 14/52 and a 14/51 would be.....3.71 - 3.64 = 0.07. So the difference between 14/52 vs 13/48 is much less than going up just a single tooth on the rear sprocket.

FWW's do help, but they will not magically take away the two stroke hit. My new 300XC has an almost electric feel. Playing with the power valve springs really makes a huge difference on the bike.

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Tomac and/or Anderson for 2020.....

8/30/2018 9:58 AM

BobPA wrote:

I think you may have your ratios slightly mixed up. A 14/52 gives you a 3.71:1 ratio, while a 13/48 gives you a 3.69:1 ratio. ...more

Oh I'm well aware of how close they are, I want them to be similar in how quick the bike picks up, I was thinking there is something to the smaller rear sprocket that would allow the suspension to not load up quite as bad as the 14/52 did. Like I said, I could 100% be overthinking this thing.

The hit wasn't so bad, it was more the tractability in slick conditions. In Sand I could ride the bike as is for days, loved it, could push until my arms gave out. Just pin it and lean into the turns. Throw in a jump out of a turn and I would mentally wet my pants.

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8/30/2018 12:56 PM
Edited Date/Time: 8/30/2018 8:22 PM

The larger front sprocket takes load off the suspension. Keeps the chain in a more parallel shape most of the time.

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8/30/2018 12:58 PM

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8/30/2018 7:54 PM

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8/30/2018 10:15 PM

TJMX947 wrote:

The 13/48 and 14/52 are really close but slightly different. The 14/52 was really snappy and was more of a on or off motor, ...more

BobPA wrote:

I think you may have your ratios slightly mixed up. A 14/52 gives you a 3.71:1 ratio, while a 13/48 gives you a 3.69:1 ratio. ...more

TJMX947 wrote:

Oh I'm well aware of how close they are, I want them to be similar in how quick the bike picks up, I was thinking there is ...more

For tractability you want the flywheel weight

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8/30/2018 10:49 PM

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

8/31/2018 12:52 AM

The 250 2T does take some getting used to, especially jumping. I found I was jumping front end high the first few times I rode one too. I find on the 250 I need to accelerate up the up ramp and then just roll off a little at the lip. Suspension also plays a part, standard yz suspension has fast rebound, slowing that down and also going in on the high speed compression helps too.

I have a 9oz fww on my 250 as well. It just takes the edge of the 2 stroke snap, still no mistaking it's a 2 stroke. I mainly ride hard pack and it's great. When I ride a really tacky track I sometimes feel that it takes a bit too much snap away but it just let's me get on the gas a bit earlier.

I recently put a dep pipe and standard length silencer on it. This took a little bit of the initial snap the stock pipe has then builds a stronger mid range and top end with more over rev than stock. Very good pipe and, boosts power but is very smooth

Biggest improvement I made was putting a pirelli mid hard rear tire on it. I used to run a pirelli mx extra x, it was ok but a tire designed for hard pack makes a big difference

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8/31/2018 6:26 AM

From my experience of owning an RM250 for 8 years...

FWW's work (the RM has a lighter FW than the YZ as stock anyway). I tried both a 6oz and 13oz. The 6oz didn't make enough difference to warrant the cost.
Longer silencer = smoother power. Shortys sounds great and give loads of hit, but are more difficult to ride in slippy conditions.
Ensure your jetting is perfect. Good jetting will give a smoother transition through the power band.
Definitely play with gearing.
Do not ignore your tyres. Don't buy low quality ones and pick tyres that are best suited to your conditions. Also play with pressures and set them accurately.
Look into a G2 Throttle Tamer. I purchased one when converting an RM250 for enduro and was incredibly impressed with the extra throttle control it gives. Not ideal for hardcore racing but for beginners or low grip/techy tracks it works great.

It's easy to go OTT and do to much. My current set up is a 13oz FWW, v force and Pro Circuit exhaust. Totally stock engine with just minor jetting and powervalve tweaks.
As mentioned, technique goes a long way on a 250 2 stroke. Spending a lot of time on one will make you a better rider.

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@russ_69