Work continues doing a low budget fix-up on a 74 DT175 for a 16 year old neighbor to try his hand at AHRMA Vintage XC.
Engine is together with new piston/rings and both crank seals.
Carb is damaged (pilot jet seized/mangled and pilot air screw seized tight) so I'll hit my local bike bone-yard and try to find a decent replacement. Bike will not start with $16 Chinese carb...

Anyway...my questions:
I've worked on many CT2/3's with the flywheel magneto. This Dt 175 has a mechanical advance unit. Seems silly to me...it's a 175 for Pete's sake, not a 500! The unit on this bike does not move freely...it does "open" but seems reluctant to return to the retarded position. 
Do any of you simply wire the advance open using a small loop of thin s/s safety wire and be done with it? It is timed now at 1.85 mm btdc (advanced) using a dial indicator (genuine 1970's Yamaha!) and a 12v battery/bulb. I do not recall CT2/3 or the DT2 I worked on last year having an advance...

Second, I noticed a diode wired in-line on the ignition wire. I've read in another post this is to prevent the engine from running in reverse...which the 60's era Bultacos were prone to do...hilarious at the start line of an enduro! Is there any OTHER reason to retain that diode? I have removed it.

Third, the bike is equipped with one of those orange "magic coils" that are supposed to work on almost any ignition system. They worked fine for me in the past on a 71 Husky Femsa magneto as well as a 64 Triumph Tiger Cub with the dreaded ET ignition.
My magneto is putting out a big fat blue spark on kick over. So...any reason NOT to stay with that orange coil?

As before, I appreciate any advice or suggestions.
Sure hope I can find a correct good condition carb.

Yes you can wire advance fully open.  Set timing at full advance.  Yes, diode can be removed.  No reason to change coil.

“Sure hope I can find a correct good condition carb.”

I found an original carb in really good shape for my DT175B on eBay last year for $100. The bike had a China carb on it when I got it. So they can be found if you are diligent with your search. I will watch for another during my ritual searches. Good Luck!

Could just Tig the cam in advanced position, 1.8mm btdc. Won't rattle then. Chinese carb shouldn't be the reason it wouldn't start, unless its bunged up from sitting. Have one on my 175 & she rips!!. Here's a link to the page with vid, rather than blockup your post with my vid.
yamaha-enduros.com/index.php/forums/gene...5500-rpm-in-5th-gear