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  1. #1

    96xp will only run with the choke on? please help it is brand new, can't get to run

    Hey guys built a 95xp800 to bring to the shore this week for vaca. Built the whole boat from scratch and everything is brand new or re-done. Currently the boat will idle but as soon as you go to get on it she dies. If you give it some choke it will try and run but still wants to die. I am in the break in process where I did the 2 minuets on, let cool, 5 minutes on let cool, 20 minutes on let cool, etc etc. Now is where I can put some hours on it and it won't run.

    bone stock 787, none ported cases. yes I do I have watercraft magic sleeper porting on the jugs and pro-x 2nd over pistons but that is it. stock pipe, stock carbs etc etc.

    So far I
    -I had the fuel tank "on" and "res" t'd together into one 1/4" fuel line directly to the carbs. Figured maybe it's sucking air? So now it is just one 1/4" fuel line from the "res" or reserve from the oem seadoo fuel tank and sending unit to the carbs. I AM NOT RUNNING THE STRAINER AND I AM NOT RUNNING A FUEL SELECTOR VALVE. Fuel is on at all times.
    -carb springs are the black ones, which is 80 gram spring with a 1.5 needle seat. should be 38psi of pop off. is that the right color spring I should be running?
    -removed the inline fuel filter, that did nothing.
    -tore the carbs off last night blew every orface out and cleaned everything again, all gaskets have an hour if that on them, and all gaskets are in line with the factory mikuni suber BN spec manual. It is running the stock carb jets 147.5 and 80 pilots i think. Whatever is stock. High speed screw is one turn out and low speed screw is 1 1/2 turns out.
    -Tried to open the low speed screw 2 1/2 turns out and it ran worse.
    -I used yamaha bond 4 on the cases and used plenty of it. Brand new crank and balance shaft so all seals and bearings are brand new. No cranks in the cases or jugs that I can find.
    -I am using a 4 hole base gasket, no yamabond on the base gasket
    -squish with the stock head is right on .50
    -Compression is right at 155 front and rear
    -All piston rings I gapped to seadoo spec
    -plugs are .35 gap iridium br8eix new
    -Pulse line from crank to carbs is stock and 6 inches long.
    -Return line to the fuel tank has no return carb jet in it
    -Carb base gaskets are perfect.
    -Seadoo rotary valve is dead on timed correctly with the degree wheel.
    -Motor was put together with the lay down method and done to a "t"
    -I don't run a oil injection pump it is 40:1

    (Do I have a vacum leak?) I cannot find a leak in the fuel tank.


  2. #2
    Here are the carb specs from

    Maybe you have them running too rich, compared to this chart? Also I don't think your pop off pressure is right. Looks too low. Like you said possibly wrong spring?

  3. #3
    kecheme's Avatar
    Join Date
    Jul 2011
    Phoenix Az
    Quote Originally Posted by 1fastxpp View Post
    It is running the stock carb jets 147.5 and 80 pilots i think. Whatever is stock. High speed screw is one turn out and low speed screw is 1 1/2 turns out.
    -Tried to open the low speed screw 2 1/2 turns out and it ran worse.
    Your high speed setting is off. I've got a 97 xp with 1mm over pistons and rec porting. My high speed is set at 1/8 turn that is with the stock air box. My mains are stock and pilots are 75.

  4. #4
    kecheme's Avatar
    Join Date
    Jul 2011
    Phoenix Az
    And put the regular BR8 in. The iridium plugs foul quickly. Just untill you get the carbs tunned.. I'm not hating on the iridium's hell my truck used them.

  5. #5
    I'm going to go yank the carbs again and see what jets are in both.

    I have a feeling my pop off is off too high not leting fuel in after the vacuum falls off. I have the black springs in and 1.5 NS that would or should put pop off at 38psi. shiny silver should put me at 32 psi

    Carbs don't have accel pumps on either.

    I am also going to fill the fuel tank to make sure there are no leaks and no air is getting sucked in since the tank is so low. and make sure fuel is pumping through the carbs if I take off the return line and see that fuel spills into the hull as the motor cranks.

  6. #6

    Join Date
    Mar 2006
    stock 96 carbs have 95 gram springs, 1.5 n/s's, 70 piolet jets and 142.5 mains-- 1 turn out on LS's and closed for the HS's

    80's w/ 147.5's is ALOT of fuel for a stocker let alone 1 1/2 additional turns on the LS's and 1 turn on the HS's...

  7. #7
    I was wrong my carbs are at 147.5 mains and 60 pilots. the carbs are from a 95xplimited ski so those jets are correct for that ski. 96xp is a little different.

    1995 XP800 787 270500215 270500216 BN-40I (SB) MAIN-147.5 PILOT-60 1.5 270500267 40 - 56 LOW- 1 HIGH- 0 - 1996 XP 787 270500284 270500285 BN-40I (SB) MAIN-142.5 PILOT-70 1.5 270500267 23 - 43 LOW- 1 HIGH- 0

    Hey guys just took the boat out 1/2 hour ago after putting a full tank of fuel in it and I changed to the shinny silver 65 gram springs from the black 80 gram springs to help lower pop off pressure to try and help the fuel starvation problem. So that did help lowering the springs because before it would stall at full throttle runs. DO YOU THINK MY 60 Pilots need to go to 70?

    Okay so boat will idle fine but off idle to half throttle it will NOT run unless you give it choke.

    1/2 to full throttle no hesitation and all the way to WOT she will run and pull, but if I let off the gas it goes right to the hesitation fuel starvation problem again and somet. If I pull the choke and pump the throttle it will run again.

    On the trailer if I pump the throttle it 'back fires' through the carbs at a WOT pull, I don't have flame arrestors on the carbs until I get it running right.

    Guys I have built like 10 seadoo XP's from race skis to rec boats.

    What the heck am I missing. This ski is so easy, it's bone stock and bare bones.

  8. #8
    -The cylinders are from group K sorry I was typing fast and going nuts not being able to tune the boat.

    -Okay the plugs before my last run, I did just clip the wires back and crimped the plug caps so the plug fits snug and they wont just slip off.
    -I also put a new set of plugs in and gapped them at .25.
    -The fuel tank was removed and cleaned monday before I installed the new motor
    -The fuel sending unit I have on RES, I plugged the ON. I checked the return and that is at RET and I also made sure the carbs are pumping plenty of fuel with the return line removed.

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