Hey guys im restoring a 75 DT250 and am currently working on the forks. I have read somewhere on here briefly about some of the earlier models having valve stems on the fork caps. My bike has these, after replacing the seals and cleaning everything up i noticed that neither one has the inner springs? i cant seem to find a diagram for these particular shocks or a thread on these. I guess my question is are these supposed to have those inner springs? or does the air take the place of that? I got a few pics of them disassembled.

That's interesting. So i guess they were still holding air then?. Someone's added the valves & done away with the springs. You'll need about 35psi of air but i'd get some springs & go back to original. I'm not sure what the top of the damper should look like but if you look does it seem like a spring has been there 'once upon a time'. looking at the link below of "76 as partzilla doesn't show "75 i think the top of damper looks the same so spring should sit ok. Looks like there's a stepped washer & a spacer on top. Bit confusing following the diagram but that generally how they work. Of course air is the easy way out for you & nothing to loose trying. I did 'that' in my "75 MX250B when racing but changed it back as made for harsh movement but maybe i should have experimented more. Was a phase we went through in "75. Then in "76 the YZ250C came out full air with bloody awful eyesore airbags on top of forks. I put springs in those shortly after buying it. In saying 'that' 'they' worked ok but hated the look. Hard to please 'me' lol. Link to the YZ250C below too for a look.

www.partzilla.com/catalog/yamaha/motorcy...t-fork-250b-c-400b-c

www.partzilla.com/catalog/yamaha/motorcy...0c/front-fork-yz250c

"Air forks" were a fad in the 70's. I tried it. They sold a kit to add the air valves to the fork caps and new fork caps with valves installed.

They sucked. If you put enough air in them to handle big bumps, they were topped out all the time and jarred your teeth out. If you lowered the pressure for decent suspension they bottom out HARD. As RT325 said, Yamaha came out with a dual pressure air system in 1976 on the YZ's but only offered it like 6 months before going back to springs.

The thing we did after wasting money on the air caps was use the stock springs and add a few psi to help stop bottoming... but the caps quickly fell out of favor and use... they did come in handy to bleed any built up pressure out of the forks... a feature some bikes still have.

I suppose i could at least try it but i think i would prefer the spring type. Unfortunately im not seeing any springs for sale, id have to check all the parts diagrams for the 250 models to see if they all take the same springs which im guessing they do. It seems as of late every time i need a part its super hard to find.

You can buy a crummy set of forks and remove the springs.

And yes parts have become scarce. Everyone is home with time on their hands so they are working on projects.