Super Jet 2004 SJ Carb Issue

[Wumpscut223]

I bought a used 2004 SJ that is all stock (everything) except for a Worx 201 Ride Plate. The ski was in very crusty internal shape. The throttle and choke butterflies were near frozen. I took the carbs out, cold dipped and rebuilt with new rubber internals using a real Mikuni kit. I did not change the jetting or any mix settings. The choke shafts are in bad shape so those had to be discarded and I replaced them with a prime kit. I reassembled the carbs to the case with all new gaskets. I changed all fuel and the fuel filter. The ski fired right up. It revs well out of water and starts easily. I don't even need the primer. My first trip to the lake....

Ski starts up well cold, idles fine in the water and has a nice 2-3kt idle speed. I get away from the docks and start to apply throttle and it revs a very very small amount starts to run more rough and dies. It starts up immediately with the starter. I have to let it idle back all the way to the dock. I put it on the bunk in the water and try to rev the ski, it doesn't want to get anywhere near a quarter throttle or it runs rough feels like it is having and harder and harder time and dies. My first day out troubleshooting skills are low so I open the hood and look around. Nothing unusual. My high and low speed screws are still covered by brass caps so I haven't touched them. I start it up and I cover the air intake with my hand to feel the suction, it feels good. When I am almost completely blocking the intake the ski runs much much better! It revs hard and pushes itself onto the bunks. To test this out I block the stock air intake tube about 60% with duct tape to restrict the flow. It starts fine and idles fine. I go for a test ride and it makes more power than the first time for about 5-10 seconds and then begins to feel like it is loosing power... the ski dies. I am not able to get past a quarter throttle but it does run a little stronger for 5-10 seconds.

What do you recommend I look at first? I am planning on pulling the carbs off right now and I'll measure the pop off and probably drill the brass caps out. I'll report my jet sizes and pop off back in a little while. Thanks for the help! :reporter:

 

[Wumpscut223]

Pop-off pump nowhere to be found... ack. New one on order. Delay of game, one week.

As a side note, does the install of a primer kit require carb adjustment due to the removal of the choke?

 

[Wumpscut223]

I'm headed off to the post office to pick up pop-off gauge.

I think I want to do a lead down test of the bottom end too. I have the needed fittings but my motor is still in the hull. Where is the best place to block off the exhaust? Do I need to pull it off at the motor and block off there or I can I block off the final exhaust port at the back of the ski?

 

[Wumpscut223]

So I found a few leaking hoses during my teardown. I made my own case leakdown tester from hardware store parts. My pulse line hose has a leak at the base. I have never disconnected it since buying it. It is a pretty fast leak depending on hose position so I could see that leading to my lean condition. I have some fuel hose in the mail that I'll replace that with and retest the case pressure.


In the attached diagram what is item 13 in the upper left corner for? The part description is just "hose". Is it water? Air pressure? Can I use normal fuel line there or do I need a different type of hose? I found a crack in this one too.

 

[Balduccimoto]

1. Sounds like you're lacking fuel in the high range. Covering the intake is the same as using a choke (its gonna pull fuel from the choke circuit). Since the brass caps are still there, a good start would be to pull those brass caps, remove the low and high adjusters and be sure to clean good inside with a choke spray and one of those red straws on the nozzle. Make sure to count the turns in on the adjusters and mark them for reference, so you can set them back properly. If I had to guess, theres a blockage in the high speed circuit.

2. No carb adjustment necessary when doing primer.

3. #13 is for water.

Good luck

 

[Wumpscut223]

Thank you. I will have a chance to mess with it in a week or so. Is fuel line a suitable replacement for #13 or do I need something different for that water? Thank you for the tips. If I replace the stock intake with a Tau Ceti style, they say there is no rejetting required but will I need to adjust my carbs? What is your method?

 

[JetManiac]

Thank you. I will have a chance to mess with it in a week or so. Is fuel line a suitable replacement for #13 or do I need something different for that water? Thank you for the tips. If I replace the stock intake with a Tau Ceti style, they say there is no rejetting required but will I need to adjust my carbs? What is your method?

Leave the stock f/a, they work better for freestyle. Remove 2 of 3 screens for more airflow. Fuel line is fine for #13 or we can send you an oem one.

Engine is starved for fuel. Recheck carb rebuilds.

 

[Wumpscut223]

I found a leak in the pulse line. I have replaced pulse line and did a leakdown of the case. The case started at 9.8psi

10 minutes - 9.2 psi
40 minutes - 8.2 psi
3 hours - 7.4 psi
This should be of no concern, correct?


So I should return my Tau Ceti flame arrestors? I haven't used them, the idea was to make getting to the carbs more simple, less junk in the engine compartment. I bought the outerwears prefilters to go with them. I wasn't expecting any noticeable performance gain, just an cleaner engine compartment with more room to work.

My stock intake only has two square screens, one over each carb.

I'll be checking pop-off and carb rebuild over the next hour. I also will be replacing all fuel lines.

 

[Wumpscut223]

I double checked the carb rebuild. No apparent issues and all passageways blew clear. Is there anything else I should check before a test ride? Anyone in New Orleans area want to go riding? Due to the Tau Ceti style F/A I lowered my popoff settings and increased the needle size 0.3. The settings are as follows:

Rear Carb
Main	130
Low	70
High Speed	1 3/4
Low Speed	1
Old Needle	1.5
New Needle	1.8
Old Popoff	37
New Popoff	24-26
Spring Old/New	115/95
Front Carb
Main	130
Low	70
High Speed	1 3/8
Low Speed	1
Old Needle	1.5
New Needle	1.8
Old Popoff	36
New Popoff	24-26
Spring Old/New	115/95