Does anybody know where to get reed valve petal replacements? Im scouring the internet and cant seem to find any..
These would be for a 1972 dt2 250. 

Yamaha hasn't listed them as a separate part , but using logic , I guessed the part number would be 311-13613-00 .
Checking on Ebay , there was at least one vendor with some available .
311 is the DT2 specific part prefix number .

Partzilla shows that they have them but they ain't cheap 10V-13610-01-00. I also looked at Boyesen which was one of the upgrade reed vendors. I don't see anything specific for a 72 but you may try calling them 800-441-1177

I just posted the same thing...  entire reed valve is still available new from Yamaha for about $125 which is what I'd do if the reeds actually need replacing.  The rubber coating is pretty old and hard by now.  

Not a fan of Boyesen but I'm sure they do make them, they definitely used to but like Wiseco for a while, the catalogs don't show the older bikes anymore.

yamabits in the UK has them

I've linked a couple of pages below from 1980 YZ80 because they're the same reed block except by memory they shaped the inside of the reed stops for better air flow--nothing realy--but i remember that from back in the day. So in the links the drop down under fitment has a thing saying see more & shows DT2-3 & RT2-3 for the gasket & the reed valve assembly Cost is getting up there but on Aliexpress where i go & i guess Amazon etc--if you knew what fits i'm sure there'd be a trick reed block for almost nothing with free shipping too. Just a question--what up with yours, or just want to replace the reeds because they're--nearly as old as me lol.

www.partzilla.com/product/yamaha/3TT-136...060beabae6fc1be05fe8
www.partzilla.com/product/yamaha/10V-136...060beabae6fc1be05fe8

I was able to find some replacements that fit thee reed valve for a 1972 DT2 250.
These were the ones from Boyesen, below.

I replaced the original stainless steel petals, which looked to be in good condition, actually.
In the process I chewed up the small phillips screws holding the reed petals in place and replaced them with hex screws. The hex screws werent the same length so I had to cut them down with a dremel grinder and added some loctite for reinstallation.

Original reed petals: imgur.com/a/dFBAgbf
Boyesen Petals 1: imgur.com/a/OlCWfsb
Boyesent Petals 2: imgur.com/a/TVafl6I
Boyesen petals purchased: imgur.com/a/6s0ML0j

I'll try not to ruin your day but if i ran those again i'd use the original reed stops. Used them back when they were first invented & with just the bar supplied, but went soft over time & stuck so far open i had to push start. But flipped them over & completed the day ok. Cause was likely the "go fast" fuel we were using back then. Now nearly 50 years later i just thought original stops might give them an easier time. Used them in my sons YZ80--they used the same 250-360 RT2 DT2 reed block. Blimey it was about 47 years ago counting lol. Hope it all goes good for you.