Pop Off pressure for Aftermarket Flame Arrestors

[IDoSeaDoo]

I had a hesitation issue with my new 787 engine I recently installed. Someone said that my pop-off pressure is too high, but when I went to check it, it was only at 25psi on both carbs. This seems rather low for this engine. I DO have a very unrestrictive flame arrestor (basically a coarse screen), so what pop-off should I set it to? I was going to raise it to 35psi to avoid hard starting when the engine is hot, but I'm having second thoughts now. Please help, as they go back in the ski tomorrow. I'd hate to have to rip them out again...

 

[Dr Honda]

You can have a pop-off way down at 10 psi, and not have hard starting. Hard starting is caused by leaking internally.

I guess we need to figure out what kind of hesitation you have. Is it lean or rich. If it's lean... pull the choke about half way, and go for a ride. If it clears up... then you need more low/mid fuel. If that's the case... I would leave the pop-off where it is, and go up a size or two on the pilot jet. (Mikuni jets go 2.5 per step)


If it's a rich hesitation... bring the pop-off up... and turn the low mix screw in an 1/8 th of a turn.

 

[IDoSeaDoo]

Went to the lake with pop-off at 35 psi. Ski started/ran fine, except for the horrible mid-range bog. Turns out, I had a RAVE boot completely disconnected. Replacing the RAVE boot connector with an undamaged one, and testing again tomorrow. Hope that that's all it was... BTW, before I blew up my last engine, the ski ran just fine with the low resistance flame arrestor, and no carb mods.