I am going today to look at a 74 Honda MT250 Elsinore enduro.  All the pieces are there including turn signals and the video the guy sent shows it running, although it looks like he had to use a snort or two of startdammit on it by the spray can in the background.  I am aware of the countershaft sprocket issue where they can start to wobble and also heard of unscrupulous folks welding the sprocket to the countershaft.  I also want to make sure the oil injection system is operational but other than cables, clutch and brakes what else should I be aware of or looking for when I test drive this bike this afternoon?
I am wanting this bike to be a stablemate to my awesomely fun 77 DT250.

My new CR250M Elsinore in "74 wore the shaft out.
Terrible system.I'm pretty sure it was that one i machined or ground the teeth off a worn out sprocket & ether welded the two together or bolted them together if the splines lined up on both, then it picked up the good spline further back.
Then held it on with a circlip. Was a "get me by" at the time & maybe i was waiting for a new shaft but the weekend arrived before the shaft. Blimey that was that 50 years ago. Still got the scars lol. Threw a rod too. Actually broke a rod in two of them. No obvious reason although was always working hard. Couldn't buy a conrod kit & only came as a complete crank. By memory the Elsinore had a bobweight crank like an old British Villiers motor.
We sold Honda & Yamaha then & i was sponsored by Honda that year.
Sorry, that's got absolutely nothing to do with your post. Enjoy your MT250.

I have a 1976 MR 250 which is close to the MTs. The starting issue is most likely due to the carb, clean it and then clean it again. The pilot jet must be impeccibly clean. I am not a fan of Keihin carbs in general; slightly off topic but I finally got tired of the Keihin on my Honda XR400 and put a flat slide Mikuni on it, it used to take 20 kicks, it now takes two. My MR 250 still has the Keihin and starts and runs good, but the air cleaner and and fuel system is kept very clean. I hope that helps.

If you want a laugh [& i'm laughing after a wine on an empty tummy], this 'very lame' video we did for Honda back in "74 'i guess it was'.
That's me on the Elsinore & also looks like me 'same helmet' on the SL125 doing an impression of a wheelie lol. Funny looking back. Found it simply by googling [Honda No1 under the sun]. Believe it or not it took two days to do it due to weather at the local beach area about 30 minutes out of town in my MK111 Zephyr with bikes on trailer. Donations gratefully recieved haha.
www.ngataonga.org.nz/search-use-collection/search/C1663/

RT 325 . I remember that ad from back in the day .
 

Hey Swoop, didn't mean to put you off you Tea "dinner" lol.
There's a Suzuki one out there too with Ivan Miller by memory.

Yes , I remember that one too .
They both made off road riding look great fun .