A low-budget fix up of a beater 1974 DT 175 continues.
Hate to ask a simple question...but my Clymer manual is unclear and I can not see any exposed threads.
Is the r/h (primary drive gear) crank end nut right hand or reverse (left hand) thread?
Thanks... 

Right hand. 

I'm not aware of any left hand thread fasteners used in the Yamaha enduro engines, unless you count the 27mm x 1.0 LH magneto flywheel puller threads in the flywheel...  but that's not a fastener. 

Many thanks...I've worked on a number of Yamaha engines over the past decades and thought that.
But this one is a bit stubborn and I wanted to make sure I wasn't having senior memory fade!
As a side note...on Vintage Husqvarnas (like your 76)...the r/h side nuts that rotate clockwise when the bike is running (flywheel and tapered sprocket) do in fact have l/h threads. Many an old Husky crank end has been snapped off by someone with an impact wrench thinking they were loosening the flywheel nut. Ooooops!

Yep...a bit of propane torch heat...a stout 6 point socket on a 48" breaker bar...and off it came. My guess it was previously over-torqued...just a bit! Thanks again.

Just yesterday I took the right hand crank nut off my '71 CT-1. I put a strap wrench around the gear to brace it, and used a cordless impact wrench with a 6 point socket, and it came off very easily. Before I took that off I used the same strap wrench to hold the clutch as I removed the spring screws with an impact driver.

 

Yes, Husqvarna is different...  but starting in about 74 they got away from the horrible taper fit sprocket...  went to splined shaft with snap ring.

Husky cranks seem "brittle" too...  I've seen them snap without impact and without turning the wrong way.  But maybe were previously damaged...  anyway the threaded stub is not nearly as strong as Yamaha's. 

I just drop a piece of alloy in between primary & clutch gear & never fails to work. Or if the cylinder is off then something through the conrod gudgeon eye that's not going to damage the eye & block it about halfway through the down stroke. Maybe i'm over complicating things. Just a rattle gun & hold it by hand, it'll come off.

In my case just holding the primary gear with a strap wrench and hitting it with the impact wrench, it came off right away. However torquing it back down is going to be a different situation. This is my first time doing this, so I'll see what happens. I'll tighten the primary nut down after I have the clutch and clutch gear back on, and put a strap wrench on the clutch bracing against the foot peg, and if that doesn't hold, then I'll go with an alloy piece between the gears. I saw elsewhere where someone said they used a penny.

Quote: "Just a rattle gun & hold it by hand, it'll come off."

Thank you RT325. That's how I have been doing them all along, but I didn't want to confess to it. 

I could admit to a lot of bad practices in my shed haha but know my own motors pretty well.