Any suggestions?
There are quite a few factors that are involved in a proper burnout. Rolling burnouts (I do them everytime) can get you in trouble quick. I have laid mine down doing that a couple years ago and at that speed it did a bit of damage to me and the bike.
If you are using a street tire and stock length then I would dust it off and not worry about rolling out of it. At a short wheelbase, the bike will get sideways very quickly while rolling out of a burnout. It is very easy to lowside one. If you have a tire like a P1 it requires a different burnout than a shinko 003 at the same track. It also depends on track temps. A P1 will not need the same burnout to get to optimium tire temp in July at 100 degrees as it will 60 degrees in Dec (here in Ga). Then you have what gear preference. I agree with Brock and use first gear. Some use second gear or more. Then you have to decided if you want to use the water box. Again it depends on tire and temps you are looking to achieve.
On a Shinko DR, I use 15 psi or more, back into the water box avoiding getting the front tire wet. I pull back out after getting rear wet. I take three fingers and squeeze the front brake very tight and raise the rpms with the palm. It only requires a bit of movement of the palm to get the rpms up to 7000rpm. I release the clutch quickly in 1st gear. Do not slip it very long or ride it at the risk of ruining your clutch with heat. I keep the rpms up and rotate left and right for just a few seconds and by then the rpms should start to drop and the tire is screeching. I then stand upright, release brake and throttle slightly to the line. This works fime for me, extended, stock motor and shock, 1.4s consistently in the 60ft. If at anytime you start losing control or get uncomfortable, grab the CLUTCH not the front brake or you WILL FALL. Be careful when slowing to the line also during a rolling burnout especially with the front strapped. Too much front brake will lowside you before you know what happened.