So just for knowledge purposes what are the advantages and disadvantages of raising and lowering pop off? I would think it would only change throttle response.
No advantages ... the disadvantages are it usually ends up running like crap.
OK oK ... if you change the stock air intake/flame arrestor for high performance ones, the manifold pressure will come up some and you will have to lower pop off to prevent running lean. If throttle response is good from idle to 1/4 throttle, changing pop off will only take you downhill from there. If not good run at 1/4 throttle IN THE WATER for a while, say a minute or more, and punch it. If it hesitates find out if it's lean or rich. Using the choke when it hesitates is a good diagnostic. Choke die it's rich, choke help it's lean. If it's bogging lean, lower the pop off or increase the pilot jet. A bigger N/S also lower pop off (fuel is pushing on a bigger surface). If it's rich, raise the pop off or decrease the pilot jet size, or use a smaller N/S.
You can end up chasing your tail if other things are off. Too much fuel getting by the low speed adjuster at idle will load up the engine with gas, making it stumble rich on acceleration, as an example. Clogged bypass ports will cause a lean stumble on acceleration. You can't lower popoff enough to fix that problem. If your N/S is leaking raising pop off usually won't help and if the seat seal is leaking will never help.
All the variables (Idle stop setting, LS adjuster, pop off, pilot jet, HS jet, HS adjuster) work together and affect each other. Run stock specs and don't raise or lower pop off unless you know the problem you're trying to fix will respond positively to whichever way you think changing popoff will help. Think of pop off and the pilot jet as a team. If the pop off is right put didn't fix the problem, check the pilot jet to make sure it is the righ size and not clogged. Try lowering the popoff and going to a smaller jet or vice versa. Then check the N/S to make sure it is the right size and not an aftermarket weirdo taper or seat. Use OEM springs, not aftermarket springs.
Once everything is clean, not leaking fuel or air and stock and to spec, it's hard to improve anything changing pop off.
Don't ask me to clarify any of this information because now you know more than I understand about pop off.
