Tuning dual carbs

[Lothsahn]

Been riding my 96 GTX and it's running very well after carb rebuild with mikuni. Starts easily, idles well, and runs at 54mph (speedometer) at WOT. However, if I let it idle for more than 30-45 seconds then go WOT, it hesitates (and once has died on me).

Both adjusters we're set according to the stock settings. Pop off matches within 1 psi and right in the middle of the range. Read the carb adjustment guide and it seems like I need to open the low speed adjuster a bit and retest.

How do I know which carb to adjust?
What is the purpose of the popoff valve? How does it trigger?

 

[mikidymac]

It really isn't going to help. When you idle for that long excess fuel builds up in the crankcase on a 2-stroke so when you punch it from idle directly to WOT there is a vacuum lag that happens before the carb can respond to the change in vacuum and the fuel can be scavenged from the crankcase up to the piston tops to be burned.

This is one reason seadoo went to the accelerator pumps, for emissions and throttle response they could jet them really lean at idle then give the squirt of fuel to get them going.

You could try adjusting the low speed screws in about 1/8 of a turn but it probably won't make much of a difference as it is just the way these are.