97 GSX 787 Carb settings needed

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rkkoeb

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I picked up a 97 GSX for my son ealier this year. I went through the complete ski changing out the fuel lines, fuel filter and fuel switch. The engine has 150 PSI per cylinder and I also rebuilt the carbs using Mukuni kits. Problem I am having is the piece of paper that I used to mark down all my carb settings my son decided to use it when painting so I no longer have the settings. Here is what I am thinking from what I have read. High speed = Mag , PTO 1/2. Low speed both Mag and PTO 1 turn out but I also have read it should be 1.5 turns out. What is correct? The person whom I purchased it from said that the ski didn't run very good so the reason why I went through the carbs and fuel system. One thing I did notice when I took the carbs apart was on the MAG carb the little clear check valve was offset and covering one of the tiny holes. Not sure if the carb was rebuilt at one time but it for sure was not center over the large hole. Would this cause the ski to run bad?
 

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I picked up a 97 GSX for my son ealier this year. I went through the complete ski changing out the fuel lines, fuel filter and fuel switch. The engine has 150 PSI per cylinder and I also rebuilt the carbs using Mukuni kits. Problem I am having is the piece of paper that I used to mark down all my carb settings my son decided to use it when painting so I no longer have the settings. Here is what I am thinking from what I have read. High speed = Mag , PTO 1/2. Low speed both Mag and PTO 1 turn out but I also have read it should be 1.5 turns out. What is correct? The person whom I purchased it from said that the ski didn't run very good so the reason why I went through the carbs and fuel system. One thing I did notice when I took the carbs apart was on the MAG carb the little clear check valve was offset and covering one of the tiny holes. Not sure if the carb was rebuilt at one time but it for sure was not center over the large hole. Would this cause the ski to run bad?
Both low speed needles should be 1 full turn out from seated. MAG high speed should be 0 and PTO should be 1/2 turn out from seated.
 

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If the plastic was covering the large hole and one of the small holes would that caused the ski to not run correctly?
 
The check valve goes over the large hole. You line the other two up with holes and plate.
 
I agree but my question is if it had been covering one of the small holes what would happen
 
Nothing as the small holes, the smallest is just to align the plate and Mylar and the other one is threaded for the hold down screw. I honestly don’t know how you could install it incorrectly.
 
Ok I took the ski out yesterday for a run. At first it was OK. Ran outstanding on the trailer and once in the water it took off but I would say it was not snappy out of the hole. Top end was great, played around for about 10 minutes in the waves and started to come back to the dock in a no wake zone. The jet ski became very boggy and would not accelerate after. Put it back on the trailer and ran if for a couple of minutes, seem to clear up and be very snappy again. Put the ski back in the water and again it was very doggy so I turn around and just put it back on the trailer. I am 1 turn out on both low speed screws and 1/2 turn out on the PTO high speed screw. One thing I was thinking is I never checked the marks on the oil pump, could it be loading up with oil that may cause it to bog down like this? Could it be something with the RAV valves or is just in the carb setting?
 
I would check the oil pump but typically it won't cause these symptoms. I would make sure your check valve on the gas tank is working.
 
When you say check valve are you talking about the breather line with the two way valve in it? If so yes I checked this out when I changed out all the fuel lines, both the one that goes out the side of the jetski and the one by the seat area
 
now that I think about it I used compressor air to check the valves, could I have destroyed them doing this? I tried looking them up and it seems like nobody has them in stock. If they are bad how does it effect what I have going on so I better understand
 
Compressed air could damage the check valve. Just blow into them and see if they open and close.
 
If the tank builds too much pressure it can flood the engine with fuel. It the tank develops a vacuum it will starve the carbs of fuel.
 
Could I have a bad needle and seat? They are brand new 1.5 and I did do a pop off test and both came in around 32 psi
 
Ok I removed both valves for the fuel system. The two way valve that is under the seat is working correctly. I can blow in the valve and it will open as it should. When I blow into the opposite side no air comes out so working correctly. The valve under the rub rail I can't blow through either direction. If I use compressed air I can get it to work but i don't think this is correct. I thought I should be able to blow through as I thought it only had like 1.5 pounds of pressure needed. When I removed the first valve off the fuel line all kinds of pressure was released, is this normal or could it be because the valve under the rail is not letting air exscape?
 

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