800BB will not rev out

unplug your tach and try it again.

I've had tach go bad on me and limit my rpm, it was weird, same symptoms that you are describing, so....since it worked fine in your last chassis.....unhook anything powering your new chassis and see what happens(handwarmers,tach,headlights,etc). unhook everything not needed to run the engine and see what happens.

Another thought, check your bellows in your ves valves, if they aren't opening all the way that could limit rpm too.

800 BB thoughts

Are you sure the CDI does not have det loaded in. If there is, and you do not have an operating det sensor hooked up it will not run out either. All engines have a certain amount of knock and if the ecu does not sense any it will limit the amount timing advance. (been down that road) I have tried every ecu out there on my 800s and the best one is from an 03 RMK PERC add with no DET. It will make the newer boxes with det feel like you had a fouled plug by comparison. Also, your pro x was equipped with an ignition key that selected between an 87 ethanol map and a non oxy prem map. When you asked about the wiring harness it occured to me that there is no longer any way for you to select the higher timed map without the key switch(if you truely do not have DET). When I did my conversions I added the complete harness as well to retain the keyswitch for selecting maps. According to the wiring diagram for that sled, it looks as though the prem mode is the dominant mode unless the pink/blk wire is grounded, therefore selecting the 87 map. However, I think the main root of your problem may lie in something more, such as inoperating EV valves but the timing will have major impacts on the peak performance and RPM.

With slp twins, 165 psi compression I was at a 420 main with 66 grams of weight, 50/50 prem and 114 and the 03 rmk perc box at about 10 degrees above

DET box

I went back and read through your info and am more convinced you have a ECU compatability issue. Your 03 engine did not have DET so it will not have a knock sensor or the bung under the head for the knock sensor to bolt on. You said that you had the box reflashed with the most recent 800BB map, which would likely be from a 04 or 05 with DET. If that is the case the engine will not rev out, it will run in full DET mode because there has to be a det sensor plugged in and correctly bolted to the head to run. Try a new head with DET sensor or, get an older box that has no det and has not been messed with. If you need boxes, heads, DET sensors, wiring harnesses, tachs or whatever let me know, I have lots of parts and know exacty what they are and what has been done to each.