best clutch for starting from a dead stop


my son races a jr class flathead with a 3/8 restrictor, slightly smaller than purple, they start the little guys from a dead stop, any suggestions or experience on what clutch comes out of the hole the best ? been running a greased lightning, looking to make it better for the coming season
If, on the starts, the engine is being held at peak torque, and the clutch is not producing a lot of heat, (a power loss) in any case any more than the rest, that’s the best any clutch can do.
Put a bathroom scale between the front of your kart and a “strong” wall, the clutch setting that gives you the best scale reading is the one you want to use. Be careful, don’t hold the gas on anymore than you need too. Let the clutch cool down between tests.
Comments, compliments, criticisms and questions always welcome.
I would think the vortex would be a good choice. simple and progressive spring setup. similar to constant velocity.
blueprint the greasd lightning could help if it has not been done. though a new clutch is always nice.
have your motor put on the dyno and see where it needs to come in.I always used to laugh when my daughter would drive right by the kids running the latest and greatest disc clutch and we had a 5 year old noram that was set to the proper speed.
if your allowed to run a disc clutch like the greased lightning, and money is not an object, i would be putting a bully on it, no questions asked
We've done very well with the Horstman X5 on our rookie kart (green flag from a standing start.) Very lightweight clutch and small diameter for quicker acceleration. The smaller friction area also works well with small plate engines. If you're looking at only running this class with standing starts for a year or two, you might well consider the X5 clutch as well. I've got a very nice fresh X5D available right now for $150 on here - and tons of spare drivers and baskets for them if you ever need.

Always hard to beat a Bully as far as durability, parts availability, and resale.

Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cuts
Thanks guys, I picked up a ward revo 2 disc along with a bunch of other parts recently. If it preforms as good as it looks I should be in business, no access to a dyno, but an old duffer told me put a bathroom scale between the nose of the kart and the garage wall, adjust clutch til I got highest reading on the scale... It sounds viable, and it also sounds like my kinda hillbilly tuning !
you could also have somebody hold the break down and rev the engine where the rpm stops on the tack that where your ckutch is fully engaged, but pleas do not try to hold the tire from spinning that is a real good way to get hurt