Put this in your thought process,
the intake wave pulses are 99% the culprit! unless you have the carb on backwards??!! It could happen (lol)
Here's your delima. Its a carb. F/I you'll never see that because the injectors are almost on top of the valves, well ad much as poss anyway. But air itself will move in and out of the throat as a result of reversion. bigger cams, bigger reversion, as a larger cam (read more duration) opens and closes in relation to the piston traveling up and down respectively. AIR MOVES. Engines are air pumps with fuel thrown in to keep things interesting! The only thing you can do to counteract this is put a restrictive air filter on. That will slow things down enough to create a vacuum IN FRONT of the carb and prevent the misting.
Think of an exhaust muffler, It does the same thing. (as well as dampen sound) interoduces back pressure to keep (in this discussion of theory anyway) backfiring by adding a restriction to the airflow.
So in essence, alot is going on here, check out this book from super smart people (read engineers) who made this theory a science.
"SCIENTIFIC DESIGN OF EXHAUST &INTAKE SYSTEMS" Third edition by Philip H. Smith and John C. Morrison
IT WILL EXPLAIN EVERYTHING!!!!

 

I also experience lots of spitting from my beauty. I baught it a couple of months ago and it wears drag pipes and an open air filter. I placed some home made lollipops with some improvement in performance but none in spitting. My next thought is to buy a Vance Hines straight shots to correct them all. I wonder if the cones I read earlier could help.

 

Just my two cents, something I ran into with a similar problem on an 90 something (maybe sportster) I was working on. The petcock (fuel shutoff switch) has a vacuum diaphragm that is usually rubber and a vacuum line will run from it to the carb intake side to provide fuel only when the engine is running. The bike was running extremely rich and had gas running out of the air filter. Turns out the diaphragm had several holes in it and it was sucking gas through the vacuum lines. Simple fix that took several hours and a lot of head scratching to figure out. Hope it helps! I replaced it with a non-vacuum petcock and capped the vacuum port on the carb, not as safe but it fixed the problem. You can usually get a new diaphragm to replace it if you want to keep the original.

 

i know this is was older post,but i have a 01 carb dwg,,and the issue as you described wound up being intake vacumm leak...getting new seals,,and also carb seal...should be the end of spitting back and not being able to get idle to be correct.//

 

ever looked down a velocity stack wot?? nothing but a vapor cloud. to be alarmed??, nope, can be a good thing as it is mixed well with air and ready to burn. will some leave, yep, i used to get raw fuel burns on my leg when the big dellorto was dumping back through the stack wot on the flats.

 

I've got air blowing out my carb.. pushrods are moving, the rockers and valves look to working. I'm stuck
I'd appreciate any help to get me in the wind,many thanks

 

Exactly!

 

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