advice on tuning problem

[aussiemat]

Hi All,,

got a funny problem eith my sj, and was wondering if anyone could point me in the right direction.

Firstly the setup: stock motor with limited "B" pipe, jetting as per FP instructions (wax has ridden the ski and jetting is OK)

the problem occurs on the second tank of fuel after running 1 tank thru. After filling the tank the ski runs rough in the low-midrange (runs fine up top), sort of feels like its running on one cylinder but becomes better as the fuel level drops. The most obvious sign somethig is wrong is that sometimes after a landing a stab when the ski lays on its left (carbs high) it won't rev i.e: hold wydopen on side gets just above idle and thats it, this doesn't happen all the time maybe once every 5 stabs straight the ski up and away it goes. Also adjusting headpipe screws doesn't seem to make a big differnce to the power delivery.

couple of theories:

1: needle and seat are worn causing rich condition when ski is on it side?

2: overfilling the tank then as the fuel expands its opening the needle valve slightly causing rich condition?

ski is an 07 with approx 75hrs

any help greatly appreciated

Matty

 

[dajnglst]

If you are using aftermarket flame arrestor and not the stock air box when dipped to the left the left side air intake in the hood will pick up a lot of water. It's outlet in engine compartment is on the right hand side and can foul the intake with water when stabbing on the left hand side. The inlet hose should be plumbed to the lowest part of the hull to keep water away from intake, aftermarket stuff can absorb a lot of water if intake is not routed correctly from hood.

Dip boat on the left side in flat water and see if it fouls.

Otherwise if it only does it after hard landings, check needle valve float pins or that the seat is held down correctly.

 

[aussiemat]

Cheers mate,

I am running the stock air box so yeah I'm thinking it maybe the needle & seat.

Matty