My rt2 360 is up and running,  new crank & seals, perfect piston clearance with the 2 hole / 2 ring  genuine piston 
Ignition is a vape system checked at 2.9mm btdc, mikuni vm32 carb with 240 main jet, 25:1  premix plug Chop after 1 mile wide open throttle  reveals foxy brown spark plug, do I need a head skim and port job or are they really that gutless ? Can anyone recommend a tuning guru, I used bob farnam years ago and results were always top notch ?

There is a lot more in there. You could start with basic porting, widen the exhaust port and raise it up into the mid/high 170 degree range. After porting, correct the compression ratio, get the squish band fixed.

If I had an RT, I would be keen to try an RT1-B piston port cylinder. The reed valve on the RT2 and RT3 is undersized. The DT360 got a six petal reed which was still too small. The RT1B is a piston port, which removes a significant restriction within the intake tract. It's a big bore motor that doesn't need to rev to make power, so the piston port configuration doesn't impose the same kind of compromise that it does on a motor like the R5 350.

Picking up an RT1-B piston port jug also leaves your original cylinder intact, can always go back to where you started if it doesn't turn out right. I bet it does though. A properly tuned piston ported 360 will have some serious guts.

My RT2 I tried different heads, cylinder porting, after market reed's, removed the airbox,  it wasn't until I got an after market exhaust that the bike came alive , If I would have started there I may have been satisfied enough to do all the porting stuff, I tried a torque engineering whispering Smith, a GYT pipe and a Bassani, the Bassani made the biggest mid to top power, the torque engineering has a huge fat power band right in the middle that's perfect for how I ride it , also the stock airbox is restrictive in my opinion, it needs a better airbox, I used a uni foam pod style for better mid to top power , carb jetted accordingly 

First thought if it's underpowered is exhaust carbon restriction in the spark arrester deep down in the end which is non removable--in theory. Mind you if it was that bad I'd think a plug chop after full throttle extended run might come up black instead of brown from.
Missed the last word by the looks.probably was 'from a clean exhaust' if that fits.

My first question is what are you comparing the performance to?

When we were kids, a 175 seemed pretty quick... and it was in the days of sharing roads with VW bugs and other cars that could barely hit 65 mph and took more than 20 seconds to get there.

That was one of my biggest adjustments when I got back into riding these old bikes.... they are MUCH slower than I remember them being.

(Having ridden them both, my 2017 XT250, which is anemic by modern standards with about 20 hp is actually a pretty even match for a DT360 performance-wise.)

If you give me a call I could help you a lot with this stuff. 702-858-9177. Check out my website Rich's tailoredporting.com