1997 Seadoo XP Correct Pop Off Pres. and Needle & Seat Info Needed for starting issue

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masterminds

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I have a 1997 Seadoo XP and it is hard to start in the water or out of the water. I have to give it almost full throtle then once it starts i have to back down the throttle slow to keep it going or it will die out. Once I do that It idles fine in the water. Also it seems that i get a lot of hesitation with low rpm with the first jet going, once i get the rpm's up she rides great then once i slow down i feel the hesitation again. I have no problems with it dying or cutting out just hard to start and hesitation on the low rpm 2mph-20mph


What I have done so far:

I just rebuilt the upper end, replaced the fuel lines with clear, rebuilt carbs. I have 150psi compression in both heads, my pop off test showed me 40psi only if i pumped it hard with plenty of wd40, if i pumped soft it would just hiss down. but with plenty of wd40 it would pops every time. I thought 40 psi was kinda high though. The factory manual says it should be around 29 - 49psi. I have the 1.5mm Needle and Seat with the original jets. I also have the Low Speed Screws set to around 1 1/4 turn, High Speed Screws Completely Closed.

Any info to what i can do to help with this starting anfd hesitation? I was going to buy another needle and seat and rebuild the carbs again if needed, and maybe make several adjustments.

Also I need to replace impeller and wear ring, however it should have nothing to do with the starting and hesitation i think. I need some expert advice. Also I have not tried to blow out the air fuel lines but will do that when i receive a new fuel baffle since my guage is not working. This has been a fun experience.
 
It will run at 40 psi if you have the stock air-box on it... but I personally would like to see it around 30 to 34 psi.

Your problem is lying in the "If I pump it soft, it just hisses down." You have a leak somewhere... and since you are dealing with a pressure carb... you need to find that leak.

Finally... Since you just did a top-end on a 15 year old engine... did you check the lower half?? A case leak will cause issues. Also... when the rotary valve wears out... hard starting is always an issue. So... check the valve for high clearance, or being out of time.
 
Any suggestions on pressure test for entire carb set-up, also I have checked the bottom end of the case and looks good, did not have excessive clearance to be noticed however i did not perform a leak down test since it does run somewhat good once started and running. Also i did check the rotary valve for proper timing but i did not check clearance. The Rotary valve looked to be in good condition and did not see any pitting or obstructions on the plate. How would i check clearance? I can adjust the carbs with lower pop off springs and check all my gaskets again. Any special instructions or tips on carb rebuild? I have a custom pop off tester I made but like i said it only pops if i apply pressure fast. If i apply pressure slow is kinda just dont pop. Sounds like another weekend project for me.
 
If it's your tool that you suspect is leaking... then it's useless. It all needs to hold pressure. Ideally, the carb needle and seat should hold 10 PSI without leaking... but if it's all put back together correctly... and there is oil on the needle... then it should hold pressure right up to the pop-off.

I know a lot of guys here use WD40... but I like a light machine oil for the tests, and for lubing the O-rings before I put a carb back together. (Like 3-in-1)

Nothing really special to tell you on the rebuild, other than to make sure everything is right... everything is clear... and DO NOT skip over a step because "You think" it's OK. Kind of like saying, that you didn't do a leak down on the crank because it's ok. Until you do the test... you don't know. And an air leak is everything at low RPM's.
 
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