SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Sep 2013
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    ohio
    Posts
    5

    Default 1999 TigerShark 770TSL multiple engine questions

    I am working on a pair of TS 1999 770 TSL boats for a friend. One boat a cracked exhaust manifold. The other was said to not run and that it had no spark. After investigating the boat that would not run. There was about a quart of NASTY black oil in the bilge. As I cleaned the bilge I discovered the oil injection pump had been removed and replaced with a block off plate. The oil tank was full and the outlet plugged with a cap like I see in the adapter kits here. After cleaning the bilge, I the started testing things and found the starter is stuck. After removing the starter I found the engine was also stuck. I have not investigated the starter other than to remove it. I was able to free the engine with not much effort by using a wrench on two flats I found on the drive shaft. I have determined the engine needs a major overhaul or new engine.

    I swapped the good exhaust manifold from the bad engine to the one that runs. When I removed the broken manifold from the good engine, it had 3-4 ounces of nasty black oil in the manifold elbow. Is this a normal situation? I used to race motorcycles (many years ago) and never have seen 2 cycle oil like this.

    I called the owner and informed him that one boat had no oil injector pump. I am assuming from his reaction to the news that he has NOT been mixing oil in the gas on this boat. So far I have looked into the exhaust ports and see the rear piston is badly scored. Then I removed the head and the rear cylinder is just as badly scored and must be re-sleeved. I have no idea what the bottom end looks like. I assume it has needle bearings so it is possible the crank is not ruined. But I cannot be sure of that. I am thinking it might be best to simply replace this engine with a rebuilt one, If he wants to have it repaired.

    My questions are;

    1) Is regular TigerShark injector oil BLACK? I have never seen black 2 cycle injector oil. Typically it is blue or green. I have seen some synthetic 2 cycle oils that are red. Also there was so much of this black unburned oil in the exhaust manifold of the running boat.. is this a normal situation?

    2) Does the crank have needle bearings? What are the odds the crank has survived being run without oil until the pistons made the engine fail?

    3) Has anyone used a SBT rebuilt engine?

    4) I need to decide if I should get a new oil injector pump for the one boat, or take the one off of the other boat so they are BOTH the same. I am leaning toward taking the other pump off so that both boats use the same mixed gas. Any thoughts on this? We used to take them off of our race bikes so we could mix and be sure to have the correct ratio.

    5) Finally is there an easy way to check the ignition system on the broken boat since I cannot crank the engine over? Maybe take the cover off the front and move the sensor manually back and forth across the flywheel?

    Thanks,

    John

  2. #2
    Joined
    Mar 2003
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    SBT
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    Default Re: 1999 TigerShark 770TSL multiple engine questions

    The easiest way to answer your questions is to tell you to remove the engine and take it apart straight down to the crank, get a factory service manual and check the specs to the electrical system, good 2 stroke oil is not mucky black, what you see is gas and oil possible some water all mixed together, typical to see in the exhaust system, SBT sells over a thousand cranks every season and they all come with a 1 yr warranty.
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

  3. #3
    Joined
    Sep 2013
    From
    ohio
    Posts
    5

    Default Re: 1999 TigerShark 770TSL multiple engine questions

    Does SBT sell service manuals? I can find up to model year 1998 on other sites, but nothing for 1999. Any idea how different 98's and 99's might be. Perhaps engine and mechanicals are the same with cosmetic changes that do not affect how it is serviced?

    Thanks,

    John

  4. #4
    Joined
    Mar 2003
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    SBT
    Posts
    21,555

    Default Re: 1999 TigerShark 770TSL multiple engine questions

    The engines stayed the same, the hulls and jet pumps may vary through the yrs.
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

  5. #5
    Joined
    Sep 2013
    From
    ohio
    Posts
    5

    Default Re: 1999 TigerShark 770TSL multiple engine questions

    Fast forward... I ended up buying these boats from the guy. Got one running by swapping parts, and had a great time with it. I bought an SBT engine for the one that was damaged from running with no oil. I have it installed and almost ready to splash as soon as the weather warms up.

    As time went on last summer the engine that was running started making a lot of noise (internal rattling) as it was used. Compression also started dropping. I have it apart now and find the cylinders are just worn. Looks like it may very well be the original engine. I am going to order a top end kit with with cylinder soon.

    Right now my question is about carburetor jets. I have heard that the jets need to increase in size when you switch to premix fuel. The manual also that they should be bumped up in size then using Oxygenated Gas. Since it is nearly impossible to buy fuel these days that is not oxygenated, and I am going to remove the oil pump so they are both the same, it seems I have two indicators for changing jets.

    It turns out these boats are 1998 model. They each have 2 Mikuni BN38-37mm carbs. Everything is stock. The jets now are Low 57.5 and High 125

    Can you give me a recommendation for proper jet size?

    Thanks,

    John

  6. #6
    Joined
    Jun 2016
    From
    Clearwater, Florida
    Posts
    277

    Default Re: 1999 TigerShark 770TSL multiple engine questions


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