Clone clutch

I suppose you could use the word "junk" to describe that old stuff. Most everything, karting related, from that age, could be called junk when/if compared to todays stuff.

What time are you speaking of? I raced for about 20 years, followed by 20 years of active participation and then some. How long have you been in karting? I'm getting close to 55 years.
I am at 39 years strong and 46 years old and been in a kart shop since I was 10. I still race so anything racing that gets outdated is considered junk to me...LOL I Still use an original Mayco chain breaker. We have been around long enough to have every issue of the Nunley report. You will be happy to know I made my 15 year old grandson read it as he is just starting to venture into the world of 2 cycles and tuned pipes... He needed to understand exhaust temp and you explained it very well.
I have piles of old junk... K78s k35s k88s k55s DXL clutches Burco clutches, bystrom clutches, some Burco Superstars.. To me that junk is priceless and a part of who I am.
Regarding the OP's question from quite a while ago...
More and more clone builders are getting peak torque at, or near, 3900 today.
We used to set everything up around 3600 for the clutches we build for adult clone big pipe, but anymore, they need to be higher than that.
We weight and spring them properly for that range, then it's easy enough to adjust them to fine tune exactly where you want it to engage.

🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
Carlson Motorsports on Facebook
32 years of service to the karting industry
Linden, IN