WD-40 sprayed on the lines etc will cause the motor to smooth or rev up a little if you have a vacuum leak.
I've heard of folks using brake clean or even Ether too. (OMG
)
But brake clean/etc can go bang if there is a spark...
Ride safe, Ted
Please.... DONT use BrakeKleen....not for fire risks, but because when it is exposed to high heat, or burned in the combustion process, it produces phosgene gas....
Deadly, and at the least very extremely harmful to the body, in the most minute amount.... one whiff is enough to do damage, permanent health damage...
When trying to find an intake leak, use a simple propane torch, don't light it, just pass the end so the gas cam be sucked into the probable leaks... done outdoors, its simple, and safe, and you will not risk anything.. just turn it off when finished....
In addition, intake leaks really don't manifest themselves by "having to spray starting fluid in".... the common symptom on an intake leak is the bike, once started (a bike with CVK carbs) will not return to low idle speed correctly...
There is more to this than a vac leak..