Don't forget to attach the master-link clip in the proper direction! The "opening" of it points in the reverse direction of chain travel. See 5:40 for what it looks like.
I bought a new 1977 DT 400 for $1,000 when I was young, those 2 strokers were so simple. I put an MX head on it and a 67 degrees full throttle, magnesium front air forks with 11inches of travel. It was the 1st year for the mono shock. Now I drive a 2002 VTX 1800R (my 14th m/c) and will never go back to chain drive. I appreciate your videos, they remind me of the enthusiasm we have in our youth.😊