Js440 Carb Questions

[american024]

quick question. got a kawsaki js 440 with a coffmans 550 exhaust and intake manifold, has a mariner waterbox. the ski runs like ******** without the gas at half throttle, if i take off the power is there, if i give more than half throttle it bogs and wants to die.i started messing with the high and low screws and it ran a little better but i planned on pulling it off and going through it? dont know if it needs to be rejetted because of the pipe and waterbox? im used to atv's and dirtbikes and always rejett my carbs to what i have on the bike, dont know much about the ski carbs, maybe the stock settings? or if anyone has setting that are close to what i need? or do i just go and tune it to run good and record the settings i tune it to? any help id appreciate.

 

[WFO Speedracer]

It has no jets ,you turn out the high speed screw till it runs correctly,if it will not run correctly,you may have other issues,on some mod boats you have to drill out the size of the brass plug in the carb also putting in a restictor in the return line or a bigger needle and seat may be necessary.

 

[american024]

ok, ive tried the high speed screw, it feels like it gets flooded with to much gas and cant burn it all. if i let it rev down, then rev it up it catches. any ideas?

 

[WFO Speedracer]

Either its too rich or too lean ,you have to figure out which,the best way is to start with the high speed screw 3 turns out,find a bank you can nose the ski up to and run it,you will need to hold the ski wide open and turn in the high speed screw till the engine reaches its highest pitch or the most revs,then turn it back out about 1/4 to 1/2 of a turn from there.Try that and get back to me.

 

[gj_fx1]

aftermarket manifold. Is it the stock carb?

 

[WFO Speedracer]

Does it have two mixture screws or three,if it has three we need to start over because that particular carb has three adjustable fuel circuits,the adjustment procedure is somewhat different.

 

[american024]

i live about 15 mins from the kings river so i can tune, i also am going to the shop we keep all the toys at later today, i believe its the 3 screw carb. i was pretty much given the ski, and it has alot of work done that i wasnt told, the manifold isnt stock but has no marking. it has a coffmans 550 exhaust and a mariner waterbox. ill go check and post what type carb i have, thanks for all the help!

 

[american024]

only has the high and low on he carb, so its the carb with two mixture screws?

 

[gj_fx1]

has it round or square covers on the sides? I'm just thinking of this because one reason to run an aftermarket manifold is just so you can run a newer SBN/square carb. They also have two screws but have replaceable internal jets (plus the screw adjustments are different).

 

[american024]

has it round or square covers on the sides? I'm just thinking of this because one reason to run an aftermarket manifold is just so you can run a newer SBN/square carb. They also have two screws but have replaceable internal jets (plus the screw adjustments are different).

round covers, its appears almost the same as a x2 carb