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  1. #1

    Weak/bad Spark or Carb Problem

    Having an issue with a '00 Ultra, with skiworx 1.5 mod, running modified stock carbs, and Prok F/A.

    I'm not able to get up to full power. On new plugs, the ski acts like it almost wants to go, but never really gets up all the way. Instead kind of surges in the high power band. If you let up and go back down to idle, ski runs worse, even farther away from full power at full throttle.

    #1 Cylinder is relatively cool after running for a while in this sick state. #2 and #3 are hot as would be expecting on the heads of a running motor. Pulled the plugs again, #1 is fouled like crazy, after only about 20 min or less of burn time, 2 and 3 look good clean, and almost new.

    #1 is getting a spark when I use the starter to turn the motor over with a new or clean plug grounded to the block.

    Compression checks across the board, 150 psi, give or take a gauge needle width.

    Suggestions on where to look first?

  2. #2
    btldigger's Avatar
    Join Date
    Feb 2007
    lebanon tn.
    It sounds like #1 is way rich. Have you talked to steve about it? My guess would be that it needs one of the washers taken off the slide needle. Might help to adjust the air screws.

  3. #3

    Join Date
    Sep 2008
    Seems like you oughta get a lil heat on no. 1 after running it even if it is rich, unless it is gushing fuel into that cylinder drowning that plug. Take a new plug and break off the bottom electrode. Attach it to no. 1 wire and lay it on block. If spark occurs, then ignition system is ok. Then it is fuel related to that carb.

  4. #4
    Have tried getting a hold of Steve by phone, left message, but it's hard to get anyone to answer the phone, even less likely that messages get returned.

    I'm taking apart #1 and #2 together, essentially so I can compare the bad one with a good one. So far, #1 and #2 have been identical. 4 washers on needles, 165 main jets. The only difference I have seen is that on each needle there are 3 light colored washers, one darker. On #1, this darker one was the last washer put on the needle, on #2 it was the first on the needle. The slightly darker washer is just a hair smaller than the others. Could this order/size difference be significant?

    What are the risks of pulling a washer off the needle?

    The service manual really doesn't mention the washers on the needle. Are there any on the needle in the factory configuration?

    Any suggestions on removing the pilot jet, besides finding a screw driver that is just the right size (in between the head size of every screw driver I own)?

    This is the first carb that I've ever really gone through, what/where are the air screws?

  5. #5

    Skiworx 1.5

    I have the exact same set-up as you and I know alittle about the carbs.

    The order of the washers has no effect. The washers are there to pull the needle back out to richen up the low range and the midrange. So if you remove one it will lean the motor out slightly which may be what you need.

    I would first find out if your lean or rich and then head off in that direction. Have you tried your factory airbox to see if it causes any change. Try the box stock and then over the air holes alittle and see if it gets worse or better.

    Have you tried running the boat with the seat off and how does it run?

  6. #6
    I've run with the seat off enough only to play with the stinger mod pressure valve setting. I have not really tried it when trying to do a run or anything.

    Running has been mixed so far. The plugs look like #2 and #3 are fine, just #1 is way rich.

    Is it common to have the cylinders set up differently carb wise? From a outsider perspective, it would make more sense to me that they be identical in set up.

    Stock airbox is not really an option to run with right now, I left it at my mom's to avoid having an over abundance of spare/alternate parts filling my small apartment.

  7. #7
    The carbs sound identical with just the order of the washers being different. That doesnt matter really. think of it as just a way to shim the needle out.

    The airscrews are underneath the carbs next to the oil line nipples. You could turn them all in and reset them to factory turns out to start. Understand these are airscrews so the more you trun them out the leaner it gets.

    I would check for trash causing you #1 carb to flood out. Maybe check out the float spring and see if it's sticking. You mentioned the service manual, have you checked the plastic tip on the diaphragm valve needle?

    Have you checked the float arm level to see what it at. I'm just working thru the checks.

  8. #8
    btldigger's Avatar
    Join Date
    Feb 2007
    lebanon tn.

  9. #9
    I've gone thru and clean/blown out the carb. Float arm is within 1-2 mm service manual tolerance limit.

    Anyone have some service manual insight as to how many turns the air screws should be at? I'm unable to find anything.

    I'm going to pull 1 washer off the #1 carb I think. I'd like to know a baseline on the air screws prior to messing with them too much.

    Should I pull more than 1 washer? I've got some time before I can ride again since it probably isn't real easy to tune through a hurricane, so I can look at some other things if people have suggestions

    If anyone could take a picture of the air screws, I'd be appreciative, to verify that I am looking at the right things, though I don't see anything else in the location described by shogun.

    Thanks all

  10. #10
    Excellent timing blt

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