Demon carb problem

[DAVID GAGNARD]

I've been running a 650 Demon DP for about 5 or 6 years now with practically no trouble or adjustments.....Lately it has not been running well when cold and not much better after it has warmed up....

Basically, once you rev it a time or two, whether in gear or not, it doesn't return to it's normal 900rpm idle, instead idles about 1400rpms. You can "stab" the throttle or pull up the pedal with your foot, doesn't seem to make any difference, every now and then, it will return to it's normal idle.....adjusting the four corner idle circuits makes little to no difference,in fact the primarys can be screwed all the way in and it runs the same..........

So today, got home early from work and decided to pull the carb and go thru it. Everything looked good, no trash it in or anything to lead me to the problem. Took it completely apart, including the baseplate and checked out everything, blew out every little hole/port with compressed air, thinking maybe a piece of trash was the culprit, didn't see anyhting....

Re-assembled the carb with new gaskets and put it back on the motor and re-set the floats, cranked it up and it's the same story. At one time I had all four of the idle adjusting screws turned in all the way and it made NO difference....I read and re-read the manuel that came with the carb, just can't figure this one out!!!!!!!!!!!!!!!!

The motor will rev just like normal and once past about 1500rpms, runs great, just under 1500 rpms is where the propblem is......

BTW: I've rebuilt a whole bunch of Holleys and I'm kinda handy with them, Demon is basically the same carb....but this time I'm stumped big time....

Any ideas/suggestions other than getting another carb?????

As I said earlier, for 4 or 5 years this carb ran trouble free, this just started a few months ago and has been getting a little worse....

David