Bike recommendation for 26 year old newbie?

This. Not intimidating for newbies. Friendly on your wallet. Use on track or off-road.

Get a klx 140 with the full size tires 21/18 and learn how to ride that. Once your beating the piss out of that I’d go to a 250f or 125 two stroke. 
 

you shouldn’t ride on a track til you have a good base of skills IMO. 

Just don't buy a 450 because you think you'll "grow out of the 250." I hear that so much from twenty something newbs. Right before they scare the hell out if themselves and never come back.

Get a 250f or yz125. My wife was similar age and smaller than you and her first bike was an rm125 and she took to that with no problems

CR500

The smart move is a 250F or 125 motocross bike.

You're a 26 year old dude who wants to ride motocross, so a motocross bike is the right tool for the job. They'll both be plenty fast without being completely trouble-inducing.

Or a CR 500, obviously.

When you say total beginner, what exactly do you mean? What specific motorcycle experience do you have? You’re going to get way different answers based on if you answer, “I’ve never thrown a leg over a motorcycle and have never tried to use a clutch.” Vs “I can ride a bike around a field and use a clutch but need more practice before I get on the track” 

I get where you're coming from but to be fair any grown man should be able to learn to use a clutch on about 2 minutes flat.

Plus you only need to use it to pull away and stop.

Edit. I forgot Americans all drove automatic cars forever, is that still the case?

man, some of yall are acting like you havent watched hours of total beginners looping out on their first ride.

It's your first bike, you don't have to learn motocross on a motocross bike. Get a beginner-friendly trail bike and then move up to a motocross bike when you're ready.

125s/250fs are no joke

If we are talking about starting with a brand new bike then I would recommend a 250F.  They are all very similar, although the Suzuki is a kick start only (and the cheapest). 

The Honda CRF150R is also a good bike slightly smaller in physical size but great for learning how to ride on a track, and will quickly build your confidence. Only down side, if you plan on doing any trail riding the 150R is too small.

A 250f is too much. It is a race bike, not a learning bike.

It will scare you and, even though its considered a little bike, it's still a very powerful machine.

I would get a woods bike of some sort first and then transition it to motocross. Once you can jump the jumps, get a race bike.

A KTM or Husky 150 TPI bike is pretty mellow and no jetting to worry about. The suspension can be soft for jumps though. An '06-21 YZ125 is also a good choice. The newer ones are apparently harder to ride due to changes in the power delivery. It will be a while before you should try any serious jumping so an air cooled 230/250f might also be ok to start. The KLX 140 with 21/18" wheels might be good for a total beginner too, but I have never ridden one.

Regardless of how you start once you decide to start hitting jumps get a 125 2t so you can really learn how to shift and keep a bike in the power.

Yeah the vast majority of Americans drive automatic. Only people who are super into off-roading or have a car passed down to them or something like that drive stick, the rest will avoid it at all cost. 

Find a lightly used '22 KTM 150SX.  Great bike to learn on and easy to work on.

I guess that could change things for a total beginner then, good call dude 👍

Over here practically everyone from 17 years old is using a clutch and stick shift every day to get to work or go for dinner or whatever so it transfers to a bike pretty easily.

Because it’s soooo easy to ride around the track…

What is your budget?

if you're learning to ride so late in life, probably best off starting with trail riding. Learn to use the brakes and get basic bike control down before you go panic-revving and boner-airing at your buddies track or get landed on by someone who doesn't see you.

Yes the suzuki leftovers are at good entry cost. But by the time you factor in the very low resale value in 2-3 years, the math has been done over and over again on here that you are going to end up about equal buying a leftover KTM after factoring in resale. 

Anything 250f mate. You won’t be able to ride a 125. May as well get electric start for ease of things. 
don’t get a 450. 
my 49 yo brother had his first 3 days ever of riding this year. 
He started off on a klx 140/230 then a exc 250 2t. The. A exc 250f the a exc 350f on the 3rd day. 
he preferred the 350 above all else remembering that the exc is a lot smoother then a sx model. 

ATK 700 Intimidator.  
 

you’ll never out grow it.  

Yz125 or rmz250 (preferably 2019 or newer). 2017 or newer kx250f might also be an option. The 2017-2019 kx250f is pretty easy to ride. 

Wrong place to ask here ! Just go and buy what u like ! 

Most of the decent MX riders you see start at 4-5 years old. A lot of muscle memory and how to control body mass to be able to take a jump or corner. Riders that start late around 8-12 years old typically don't develop very well as MX riders. 

when you get more into it in a few years you'll probably realize there's more substance in off road riding. Eventually you'll get tired of expensive and crowded public tracks that give you 4 laps at a time. off road is a bit more bang for the buck these days, more beginner friendly, a lot safer on bones and body

If you know someone with a bike 250cc or less to try that would be good. The trouble is there aren't any full size 4 stroke bikes smaller than a 250 and 125 2 strokes can be a little more tricky to start on. As was said above 15 year old kids get on 125s after they've been riding for 10 years already. 4 strokes are easier to ride, but 250s do have more power than 125s so be careful you want to have fun, not trips to the hospital. 

With a 4k budget you'll probably be buying used and 4 stroke mx bikes can be a bigger gamble as fas a s engine goes. 

You could also look for old Honda XR250s or yamaha WR250s, they aren't mx bikes but they are full size and can be ridden on a track at beginner speed. Engines are more reliable than the pure mx bikes and alot of them aren't as thrashed.

If buying used try to find a super clean bike not a roached one. 

Take your first ride on grass, not pavement, just in case.

26 isn't too late to start riding motorcycles, you'll never be a pro but that wasn't the point anyway, riding dirtbikes is fun.

If you're a total beginner, as in, never ridden before, I'd still go a 125 or 250f but put a rag over the air filter. That will dull the power right down and when you are ready you can just take the rag out and have normal power. That saves you stuffing around with heavy old trail bikes that you'll grow out of quickly. 

I did the same thing with my daughter on her yz65 and then yz85. Only took a couple of rides and the rag came out of the air box

With that budget, buy the nicest Kawasaki KDX200 you can afford.  Anything 89+ will work.

They’re forgiving, still have decent parts support, and are easy to work on.  You can realistically pick up a nice one, ride it for a few years, and sell it for what you paid.

There’s a few KDX Facebook groups and I see nice bikes in there daily.

Yes they’re a “woods” bike, but it’s a good bike for building fundamental riding skills.  Realistically you’ll want to likely do some trail riding and learn some of the basics before you ever set foot on a track.