I’ve always ran 520 o-ring chains on all my race bikes since the 1980’s but this is my 1st vintage legal Yamaha enduro. I really want to run a o-ring chain.

 Since the o-ring or x-ring chain is slightly wider than a conventional chain do any of you guys know if the o-ring Chain is gonna rub the engine cases at the front sprocket?

I Wanted to ask before I order a new chain and spend the extra $$$ on a oring chain

Thanks again for everyone’s help with this project 

I will let you know tomorrow. I have an RK 520 o-ring chain that is going on the bike once I wake up, get some coffee in me and plop the engine in to the chassis.

Man that was perfect timing! I never even considered it until I put a X-ring chain in my cart with Rocky Mountain ATV and it told me that it was not compatible with my 1975 dt400. The Google gave some mixed info as to it would rub the engine cases or not. Thanks for your help!

DID makes at least one narrow x-ring chain.  Modern KTM's need them as a normal o-ring chain is too wide to fit.

I've had success with the DID VT2 series of x-ring chains on my vintage bikes.  It has always worked.   I don't think I've specifically used it on a 75 DT400 though.  

The VT2 chain seems to be discontinued.  It looks like the replacement is the "ERVT" series.  The max outside width (pin length) is 0.736" so you can compare that to the width of the standard chain you have now.  

(The older VT2 was only a few thousandths wider than a non-oring chain and a lot narrower than a standard oring chain.  I expect the ERVT is the same narrow design as the VT2 with a new name?)