black spring

Did a search, some info, so thought id put up a thread. I'd like feed back from any and all about what stall speeds and clutch springs worked best for them. Please include gear ratio (or tooth counts), tire size (diameter), bike and rider weight, camshaft, clutch make, spring color codes...

I couldn't stand making one boy watch the other riding, so I caved and bought a DB w/97cc. The little guy is a small 10yr old. No way he can handle the 212cc on the Sensation--I always ride with him. He can handle the DB with the 97cc just fine on his own, though. Older boy (almost 13)...