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Eratic Spark On Both Cylinders

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  • Eratic Spark On Both Cylinders

    I have a 95 Tigershark Daytona that is extremely slow on take off but runs fine once it planes out on top of the water. I rebuilt both carbs and installed new jets even though the old ones looked fine. I have attempted adjusting both high and low speed settings every way possible. I went to check the timing and stumbled on to something. At idle to about 3/4 throttle the timing light missed (not constant) on both cylinders.

    [ September 18, 2003, 06:55 AM: Message edited by: Shark1 ]

  • #2
    never seen a ignition problem on a twin but it may be a stator or cdi problem. The only way to fing out is to replace them with new or know good ones.

    If it is running good at high speed I would not think it is a ignition problem since that is when they have more problems.

    How is the compression of the engine? Low copression will take a lot of the bottom end away. Have you checked the reeds for broken pedals or cracks?
    Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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    • #3
      Oh yeah. Already had the reeds out. They are in good shape. I figured since the spark was eratic or missing, so to speak, it had to be either magnets on the flywheel, coil, CDI Unit, or Trigger Switch which is part of the Stator on this model. As for the magnets on the flywheel, I figured since it was both cylinders then both magnets would have to be bad and that was not likely so I was kind of thinking CDI or Stator. . Do CDI's and Stators sometimes partially fail or do they normally fail completely so the motor will not start at all??

      [ September 18, 2003, 06:59 AM: Message edited by: Shark1 ]

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      • #4
        This past weekend I switched the electrical box (box with CDI, Coil, Plug Wires, etc.) from my good TS Daytona (I have two.) with the one from the problem Daytona. The problem stayed with the problem ski so I guess that eliminates the CDI. I also checked the resistances on the Stator of the problem ski and they are right to spec. I grounded the spark plugs and the PTO side had the eratic spark. It was pretty black. I swapped plugs with the good ski and the spark was fine. After about a 5 minute ride, same problem, eratic spark. Put plugs back in good ski and it ran poorly. What would foul plugs in 5 minutes?? I read in other posts that "pop-off" is important. After rebuilding carbs a few months ago and replacing everything but needles and seats I checked pop off and it was dead on at 21 psi. I did notice that it only worked using WD40 to create the seal. After it poped off at 21 then it would leak at 5 to 7 psi. After a squirt of WD40, it would re-seal and pop off at 21 again. Is this OK or is it considered leaking??

        [ September 18, 2003, 07:01 AM: Message edited by: Shark1 ]

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        • #5
          Take the cover off the carbs and look down the carb. If it is leaking at idle and dripping gas the replace the needle and seat. If it is not and the carbs are set to the factory settings then the problem shouldn't be the carbs. Normaly they starve the engine for fuel when they get dirty or water in them.
          Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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          • #6
            I removed the cover this afternoon. At idle I could not see any fuel in liquid form spitting into either of the two carbs. When I opened up the throttle for about 2 seconds and closed it back I could see some small traces of liquid fuel on the throttle plate of the front carb but it quickly disappeared in about a second. Any other ideas will be greatly appreciated?? Both carbs are set to factory settings.

            [ August 05, 2003, 07:43 PM: Message edited by: Shark1 ]

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            • #7
              The only thing left is the stator assy or flywheel. Not sure what else to try besides them.
              Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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              • #8
                Swapped stator this weekend. Still did not correct problem. Did not bother swapping flywheel, appeared in better shape than good running ski. While trying to test ride motor seemed to seize for an instant so I killed the motor. Compression dropped from 110 to 90 in PTO cylinder, also small silver coating on spark plug as if attempting to burn. I know its time to pull head but anyone have any ideas of problem. I could easliy put in new rings, pistons, etc. and the same thing happen the first time out because the cause has not been determined. HELP???

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                • #9
                  Maybe you had a bad crank seal causing it to run lean and therefore had no bottom end power. Or it had a bearing that was on the way out. I would pull the engine and check it compleatley. Top and bottom end.
                  Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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                  • #10
                    Pulled engine, no pressure on pressure test. Tore down and found Mag Side crank seal completely shreaded and also part of Mag piston broken. It fell down and got caught in crank and created a small puncture in lower half of crank case. Puncture is about 1.0 mm wide and 8 mm long. I would like to patch the puncture bacause this is an extremely expensive part, what is best material for patching? So far I'm only out one piston, two sets of rings, and a PTO seal for probably about $200. All bearings appear and spin great after cleaning.

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                    • #11
                      UPDATE!! Since last post I replaced crank seal, damaged piston and new rings on both pistons. Pressure tested engine, held 8 psi for 20 minutes with no leaks. Rebuilt carbs including jets and needles and seats. Tested Pop-Off at 21 which is to spec. Put in water and it ran terrible. Carbs set to 3/4 turn on High Side and 1 turn on low side which is to spec. Had to play with choke to get it to plane out. Ran about 5 to 10 minutes and burned hole in Mag Side piston. SHOULD I JUST BURN IT OR WHAT?? Any ideas?? Also, what should compression be?? Manual says 6.8:1 compression ratio but how do I change that to a PSI?? HELP??

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                      • #12
                        Compression should be around 140. Take it out and pressure check it again to see if you developed a leak.
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                        • #13
                          Pressure checked it again. Still holds 8 pounds indefinitely without losing any pressure. I was wondering what diameters the three sizes of pistons for this model are. On websites they show Standard, +0.012, and +0.022. Does anyone know? When I look down the cylinder there appears to be more gap to the cylinder wall than 0.1 or 0.2 mm. If someone put undersized pistons in it would this cause it to burn one or just cause a loss in performance??

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                          • #14
                            It would just rattle more and may cause the piston to crack. What was the compression before you tore it down? The only way to increase compression is to change the head volume but this will lead to more heat and will shorten engine life.
                            Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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                            • #15
                              Compression was a little low at 120 in both cylinders. I figured it would probably rattle and vibrate if the piston was undersized but I did not figure that would cause it to run absolutely terrible. If the next size up piston is labeled at 0.012 does this mean that much larger diameter?? That is only about 0.3 mm. I did notice one other thing. When I pulled the return fuel line of #2 Carb while it was running (or sputtering so to speak) only a few drops at a time was being returned to the tank. When I did the same on my other ski a large stream was being sent back to the tank. How can I tell if the carbs are suppling the adequate fuel. I've rebuilt, tested pop off, cleaned and done about everything I possibly can to them.

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