I think its the carb too. I recently had a similar problem with my Demon 625 cfm
. It would die at hard brake even as slow as 5 mph. I had the pwr valve changed, the jets changed, even checked the slosh tubes (you might check them to see that they are in place) and still the problem never went away. The power valve changing from 65 to 35 helped somewhat, but the problem was still there. It finally had all kinds of flooding problems so I yanked it and sent it back to Demon for warranty repair.
I stuck on an old junkyard rusted Holley 750 80508-S vac.secondary - AND ALL MY CARB PROBLEMS WENT AWAY!!!! No more dieing at hard braking. No flooding. Nothing but a great running engine.
If you are into tinkering, change your power valve to something smaller, you most likely have a 65. While you are in there, check your slosh tubes. You might also adjust your timing. Demon said to try 14, but that didn't help. Mine is set at 40.
Has this problem started since you've had this carb? Or did it run fine, then the issue started later? It could be that you are running a DP instead of a vac.secondary carb.
I am now trying a new Holley 670 cfm Street avenger from Summit. I was about to buy a 650 dp and the cust. support talked me out of it and swayed me into a vac. secondary carb. I know the 750 on my engine is a vac.secondary and I have no dieing issues anymore.
I hope to put the new carb on this week and I'll let you know how it goes with dieing. I should also get my old Demon back and hopefully they will have a detailed list of the repairs they did. I'm not putting it back on as I fear continued problems.
Anyone want a nice warranty repaired 625cfm Road Demon?
I hope it helps!