some options for a dt360 .50 oversize piston are
445-11636 dt360 piston drop in
308-11636 rt2 piston drop in
365-11636 mx360 single ring
Honda FL350 wiseco, comes piston port but its a forged piston can add windows yourself or run as piston port engine as turbodan suggests. dont try to add windows to a cast piston

if you run one of the single ring pistons listed above youll have to service it twice as often...
rings may different between each model so youll need rings to match the piston
ive attached to this post a .dxf file that you can take to a lasercutter or give to a service like www.sendcutsend.com to get a spacer plate cut out for the FL350 piston, should cost about 30 bucks.

edit: the earlier rt1 piston wont work, because the ring gaps are in the boost port area on the dt360.

would I need to mill ports in piston for options without?

Don't modify any cast pistons or they will crack, you could possibly put a window in the wiseco piston but I think it would work just fine without it in our dt360s...
the earlier bikes make the same power without it i think

thanks

per Akara advice I found "275-11636 rt1" 0.5mm over piston 275-11636-00-00 and associated rings (as in 2) 275-11601-20-00.

If Akara or someone can confirm that this old pig will run acceptably with this combo (e.g. no piston windows in skirt) then I am all set for now. Since I couldn't find root cause of meltdown I am going to strip engine down, clean out, check everything out, reassemble and pressure and vacuum test before putting back in frame and frying more Franklins.

Just read rt1 edit, so that’s not an option

I am going to sit tight til new year and see if I can secure proper piston then

Thanks all -

Honda FL350 is a reed valve, Honda did not window the piston.

Completely optional. I have one with windows and one without. I don't know which one I like best. The one with windows makes better midrange and not as much top end as the one without but there are variations in porting too so I can't say for sure what makes the difference.

The stock DT360 piston has the windows very low in the skirt. They increase the intake duration but they still close the port before the piston reaches bottom dead center. With no windows your intake timing is fixed to about 190 degrees but the reed valve ultimately controls intake flow anyway.

My guess is the 12 would be the minimum run per size, due to their setup costs, etc. it might be an interesting project to look into to do possibly a group buy? I know that some Hodaka stuff has been repopped that way. If there was enough interest, I could see the site organizing things and acting as the purchaser. I would think if greater column was ordered, a better discount might be available, making it a doable business proposition for the site.

My thought is you could skip first over, and shoot for second and third, maybe 4th if enough interest. Would need to explore with Wiseco as to their options.

Mako

PS, I am more than slightly interested as I have one of these bikes . . .

So three options based on availability?:
- Original DT piston for my left nut
- RT2 w/2 rings and no piston ports
- mx360 with 1 ring.
Is this correct and which is best course of action?

Try contacting Enduronut.
He is the guy to ask .