300/440/550 89 JS 550 Tuning Questions?

[motoman289]

So I have been doing lots, and lots of research and I'm at the point now where I'm about to dump her in the water and try it out.

Ski has cut head, kerker exhaust, west coast water box, blowsion intake, west coast intake manifold, ride plate, prop, 40:1 fuel mixture

Recently put a SBN 44 on it and I'm just looking for someone to tell me if I'm in the right ballpark, I have a 120 Low, 125 High, adjustment screws each set at 1 out, 14psi pop, does this sound about right to anyone?

Thanks

 

[amitchell]

I think you are rich with the low jet, maybe closer to 105. Pop off seams low, maybe closer to 18-20.

 

[motoman289]

So I'm down to a 115 on the bottom and a 135 on the top, would anyone recommend going straight to a 100 on the bottom and a 125 on the top, and also I'm thinking of digging in to her tomorrow and looking at the timing and possible jacking the timing to 32 degrees, she has been tuned now with the 115 on the bottom and 135 on the top and it still feels like a turd ( i know it is still a 550) but there are plenty of 550's out there that run a lot better than this, any help would be greatly appreciated

 

[motoman289]

bump for help!

 

[dbyrkit]

i put 135 high jet and 105 low 1.5 out on each screw 18-20 pop off silver spring (i think )
jet sport hc head and a coffmans 1/2 pipe no timing advance at 0 stock bore stock porting and it runs really well no bogging and crisp my mine is 550 piston port motor

 

[motoman289]

So I've worked out most of the ghosts that this thing has has with it. Ive traced and replaced many air leaks in the fuel system, hooked up a primer to the svn (helped with starting immensely), now I'm still just fine tuning the carb with different jets and playing with the mixture screws. I was wondering if anyone had an idea to why when i increase my pop off pressure from 14-18 or even 21 the carb floods out everything including the crankcase. Its running a lot better than it used to now, but it is still not as peppy as even some friends stock 550 pp.'s, any ideas would be greatly appreciated. I'm currently running a 120 high jet, mixture screw almost all the way in, and a 105 low, mixture screw turned out about one turn.