Freestyle Loading up: Carb or Prop?

[swapmeet]

Ok, i've done more reading on carb tuning than I care to know. The good news is that I know more than I ever did. Thanks to the Watcon and GroupK tuning guides on here. Very informative...

My problem: Ski is bogging at low RPM. I do not have a tach, so i'll refer to amount of throttle. From 0 to 1/2 throttle the ski is bogging. It seems like once it gets past that it friggin flys! So everyone say together... "Its too rich down low, smaller jets!"... But its not helping. Heres the rest of the story....

This is where i tell you what i'm running.
701
Single SBN 44

• 150 Main
• 120 Pilot (currently)
• 1.5 N/S
• 30psi pop off
• 115g spring
• 1/2 turn on HS screw
• Currently 1/4 turn on Low speed.

GroupK Hammer porting
B-pipe
Protec head w/ 33cc domes
MSD

Thats it I think for the motor.

I have a 12/17 swirl impeller (can't remember the brand)....BUT.. i'm running an addtional wear ring. So i have an addtional 1.5" of water in front of the prop. This was an idea that I had read about here and decided to try out. It pushes the pump back 1.5", give you that much more water to push out of the pump for freestyle 'stunts'.

I started out with a 130 pilot, then dropped to a 127.5, then a 125 with no change in the low end snap. I did the standard 1 turn out and work your way in on each jet. Then for poops and giggles i tried a 112, the ski didn't seem to want to idle unless I was like 3 turns out. The last jet I tried was a 120 and its currently a 1/4 turn out. Also I thought my Needle wasn't seating, so I tested it again and bent the arm to give a little more pressure (from 26 to 30psi) and confirmed that its holding pressure.
Nothing changes no matter what i've done to the carb.... so I got to thinking, "maybe its my prop???"

So what do ya'll think is my problem? The prop or the extra capacity of the addtional wear ring? Or do you think i'm completely on crack and need to set my ski on fire?

 

[kevbo]

The last time I had one that fourcycled uncontrollably had the arm bent too high so that the diaphragm bottomed against the cover. There is not much room so the arm needs to be flat. Your current pilot/popoff should provide very clean running below the pipe.

 

[swapmeet]

I bent the arm down to create the extra popoff pressure, hope that makes sense.

Any thoughts about the prop i'm running, or removal of the extra wear ring?

 

[swapmeet]

Maybe I should've titled the thread "prop suggestions" or "what shoes do you wear?" LOL...
Come'on ya'll! I expected a bunch of flack for running the extra ring or something.

 

[fastony]

Adding the pump ring did not load my pump any harder it just kept it hook up better, Are you sure that this is not a lean bog dead spot instead of a rich blubber when you hit the throttle? You could be just going in the wrong direction, if you are positive it's not lean the next thing might be you have way to much water running through your exhaust. I always just ran the top adjustment screw at a 1/4 turn out and that was all. The best thing I ever did was running 2 1/2 exhaust pipe and hose all the way through and through may water box and never had to worry about low speed bog because of to much water in the exhaust.

 

[mademan9]

This mit not be a big deal, but shouldnt your n/s be a 2.0? Thats what Im running on my blackjack 44. Ive always ran a 1.5 of dual carbs. Idk just a thought.

 

[swapmeet]

Mukini and GroupK both reccomend that you run the smallest N&S possible. Since it runs on the 1.5 I haven't wanted to change it. I do have a 2.0 and a 2.3 but haven't considered testing it.

Adding the pump ring did not load my pump any harder it just kept it hook up better, Are you sure that this is not a lean bog dead spot instead of a rich blubber when you hit the throttle? You could be just going in the wrong direction, if you are positive it's not lean the next thing might be you have way to much water running through your exhaust. I always just ran the top adjustment screw at a 1/4 turn out and that was all. The best thing I ever did was running 2 1/2 exhaust pipe and hose all the way through and through may water box and never had to worry about low speed bog because of to much water in the exhaust.

I'm running a Jetworks Flowcontrol, I actually had to open it up because I was melting the hose connected to the stinger. When I run the ski after a days riding to clear the water out of the exhaust, nothing comes out.
I have no idea if its a lean bog... I was always under the impression that if it leaned out that the ski would die. I've dialed the low speed screw down to 1/8th on every jet i've tired and it never ran and then died. The only symptom is that it won't start if its closed too much on the smaller jets.

Seems like running a pilot bigger than a 130 would be overkill but i'm willing to try anything on the carb.

 

[fastony]

Try a 125 jet and a pop off pressure of 20 with the low speed needle out 1 1/2 turns and then go out with the screw once you are out past 2 turns then go up to the next jet size if it seems better, If that does not help take the breather off and start it up on a stand in the water and see if there is fuel trickle in at low speed or if it is spraying fuel back out of the carb which then could be a head gasket leaking or a needle valve that is leaking or you might have some reed problem that is blowing fuel back in the carb. Hope this helps.

 

[kevbo]

A 2.0N/S will provide the full range of useable popoff while providing no chance of running dry with a single carb.

 

[swapmeet]

Ok, i'm gonna give a larger N&S a shot, and bump my pilot jet back up. Thanks for the input ya'll.

 

[swapmeet]

If that does not help take the breather off and start it up on a stand in the water and see if there is fuel trickle in at low speed or if it is spraying fuel back out of the carb which then could be a head gasket leaking or a needle valve that is leaking or you might have some reed problem that is blowing fuel back in the carb. Hope this helps.

Can you explain this a little further?

I pulled the reeds out last night while putting some Yamabond4 on the intake gasket. (I thought I had a air leak) I didn't see any damage to any of the petals.

 

[fastony]

If you have a needle valve leaking it will trickle out the bomb site when its running at idle or up to a 1/4 throttle, I have had pop off pressure hold when checked but when the motor is running the vibration shaking the carb will make it leak. Now if it sprays gas back out of the throat of the carb when you stab the throttle you can have a broken or worn reeds that let fuel spray back or a leaking head gasket can mess up your charge and not have good throttle response, just check your compression cold and then hot and that will tell if you have a problem. It sounds like you just about check all of this so hopefully a little jetting will get you going, if this does not get you going you could have a weak ignition but try this first.

 

[JonnyB]

The 1.5 N/S and 115g spring should give you around 45 psi. Not 30psi.