Need help deciding 2T vs 4T

Alex.434 wrote:

Hi. I wrote this essay on 2st v 4st back in February when we had another post like this going around (see below). They are common...

Hi. I wrote this essay on 2st v 4st back in February when we had another post like this going around (see below). They are common... Just sharing some various info from my POV and take from it what you will... I will only add, based on your comments above, usage, weight, etc the following.

I think at 160lbs you'll get around pretty well on a 125 2 stroke. I'm 200-205 (with gear) and I was riding a 2020 Husqvarna TC125 yesterday and it was hauling me around just fine. Like any 125 you need to be makin' dat power up high in the revs.... as the low/mid isn't all that meaty. That'll be your biggest take-away going from a 250 thumper to a 125 pinger. However, the modern 125 screams up top and weights literally NOTHING. Every time I take the bike off the stand I'm amazed at how light it is.

None of us know your tracks or skill. If you ride places that have lots of slow tight corners immediately into jumps... yeah the 125 will suffer. If your tracks though have like normal corners and jumps, and you can ride the outside lines, that 125 is going to sing along and sail over everything just fine.

Jetting? Throw a Lectron carb on it and never have to jet your bike again. I put one on my personal TC250 Day #1 and never looked back. I'd recommend:

Lectron
Pipe + silencer
Reeds

DONE. Go rip.

Now to answer your other question: Modern 250 2 strokes are way easier to ride than the old beasts. The 2017+ KTMs/Husqvarnas are pretty damn linear power delivery and make good low & mid, not to mention top end. I can hit inside lines into jumps just as easily on my 250 two stroke as I can on a 450/250 four stroke. The 250s also have two maps from the factory and the MXA test riders, and myself, prefer riding in the 'mellow' map which makes the bike even more manageable (but no less powerful) out of turns.

Here's a pic from yesterday on the 125


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Feb Essay from this thread: https://www.vitalmx.com/forums/Moto-Related,20/4-stroke-vs-2-stroke,137…

41 years old
C (West Coast) to B (East Coast) MX rider.
B off-road / enduro racer.
Sporadic Moto-journalist and photo shoot talent.
Expert level roadracing and Supermoto racer.
Current MX bike: Husqvarna TC250
Other bikes: KTM 525 EXC, YZ250F Supermoto, RMZ450 Supermoto, Yamaha R1 Superbike, Alta MX, Alta EX

Personally I prefer to ride motocross on 250 2st's over 250F's and 450F's. When it comes to riding 4st's I've spent a lot of time on 250F's, so am damn comfortable on one of those out on the track, and always liked 250F's over 450F's. Though recently (last Thursday) I spent an entire day on a 2020 CRF450 and 2020 KXF450 for a photoshoot, and by the end of the day had Cahuilla pretty dialed on the big fo-fiddy.

So that said, I'm even more convinced the 250 two stroke is the ideal MX platform. It all boils down to sluggishness. The 250F's suffer from this less, but man, the 450's are just big boats compared to a nimble, modern, 250 2st. You feel that weight in the air, braking, cutting down for a line, holding on under acceleration, everywhere. It's not just mass, it's the additional rotational weight of the engine, and all those extra moving parts, also.

You go from a 4st to a 2st and the 2st feels like a featherweight fighter. Nimble, agile, easier to move around, and overall doesn't tire me out as quickly.

Power
Powerwise I do notice 250F's to be lacking power on a track like Cahuilla with lots of hills and soft dirt. Riding the 450's the other day I had that moment of 'OMG SO MUCH POWER' but when I sat down and thought about it, I was coming out of the turns, into the huge power robbing hills with big jumps at the end of them, relatively the same on both the 450 and my personal 250 2st. Whereas on a 250F it's a bit more of a struggle.

Numbers: Power to Weight
0.239 hp/lb - 2020 KX450 = 233lbs and 55.8 HP ($9,300)
0.236 hp/lb - 2017 TC250 = 212lbs and 50 HP (47 stock and mine has pipe, silencer, and reeds. Mind you the 2020 TC250 costs $8,400.. so you could buy all those parts easily with the $900 you save over the $9,300 KX)

As such the two bikes are less than 1.27% apart power to weight ratio wise. Your butt dyno isn't going to feel that, but your arms will feel it... hauling a bike around that's 9% heavier (the KX450 4 stroke). The Honda weights 12.26% more (!!), the Yamaha and Suzuki 15.5% 16% more respectively (!!!!!)

Racing:
I *really* dislike the four strokes for racing. I've worked around professional racers, and industry leaders, for over 15 years. They all say the same thing, the four strokes are way more forgiving and easy to ride. Meaning, if you mess up a little bit in a corner, on a SX track (spin the wheel, almost tuck the front, etc) you can literally just turn the throttle on the four stroke and clear the triple. From almost a dead stop, in 2nd gear, a 450 YANKS down low. However on a 250 two stroke, a mistake like that probably means you aren't clearing the next jump, and someone will pass you. Mistakes had racing (not injury) consequences, which in turn led to better racing.

Costs
Four strokes cost more to build, maintain, and race. This comes from the factories and A-level teams racing them. I'm not just making this up. This is what the heads of those organizations say.

Want to build your own. Johnny Joe Vet Racer? FMF's top 4-stroke SX pipe & silencer combo is $874. Good lord help you if you race a dual pipe Honda. That'll be $1400 please. Their top 2-stroke pipe & silencer? $640, a $234 savings, or 27% cheaper.

Go ahead and price out a full 450 factory motor build, compared to a 250 two stroke, then factor in one or two full rebuilds...

In closing
In closing I feel that a lot of folks are still remembering their 2001 RM250 and then comparing it to a modern 2020 450. Try riding a current-gen 250 two stroke. The KTM 250SX and the Husqvarna TC250. They are amazing. The motors are smooth (counter balanced), power is way more linear than the old days (especially in the 'mild' map. Tracts well), and they handle like a lightweight modern chassis should. Hell my wife, a fairly novice dirt rider, took a spin on my TC250 the other day at the Pala Fox Raceway Women's Day and got off it saying "I see why you like this bike so much! It goes anywhere and wasn't as hard hitting (aka scary) as I thought!"

Ultimately buy and ride what you like, as you can see I ride all types of bikes. The above isn't an attack on anyone, just sharing one person's thoughts, and POV.

Cheers.

PS: I'm sitting at a racetrack corner working, so yes bored and have time to type as I watch bikes go 'round and 'round =]

KennyT wrote:

You mind me asking your age? The reason I ask is they I had a blast on 125’s when I was younger (under 40) . When...

You mind me asking your age? The reason I ask is they I had a blast on 125’s when I was younger (under 40) . When I reached 50 it was all 4 strokes and I never had much desire to be full throttle on a 125 anymore. To me the 250F is one of the easiest bikes to ride on most any MX track. As I got older the 450’s were waaaaay too powerful for me. My vote would be the 250F....unless you’re a kid, then I would say go with a 125 and learn how to make that thing fly by working the clutch/gearbox.