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  1. #1

    Default Sport Jet 90HP 1994 swap to a newer motor?

    I am looking to replace my current Sport Jet 90hp with another newer motor to remedy all of these electronic issues i am having. Also would like to do this due to lack of parts availability. So what motor will drop in that is newer with a CDM ignition? Would like to upgrade to the 120XR but not sure if this is a drop in, drop in meaning it bolts up to the jet drive and spline matches up. I realize i may need modify my hatch to fit a 4cyl motor but that is not a problem. Any insight on this would be great. If this helps the boat is a 1994 Baja Blast.

    Thanks.

  2. #2
    Join Date
    May 2007
    Posts
    9,267

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    In any given model year the 90's and 120's had different pinion shafts and pinion gears in the jet units = different gear ratio's - so while you can directly interchange the units (will bolt up and mesh) the 90 drive was not meant to be bolted to a 120 powerhead and vice versa.

    And the parts support for the 120's is not a whole lot better than the 90's.

    And you will obviously be looking for a used powerhead (complete) since you could not use any of your current iginition or carb components etc - the stuff on the 3 cylinder (outside of the individual sparkplug coils) can not be used on the 4 cylinder model and you would go from 3 single throat to 2 dual throat carbs.

    This means you could be buying someone else's "can of worms" and be no further ahead - so definately be careful if you go this route.

    The only Jet (outside of the outboard versions) currently on the market is the 200 Optimax Jet - so really, swapping out to a 120XR would still leave you with an orphaned model that has numerous parts discontinued and the supply of those still available, dwindling.

    I definately believe that sometimes it is wise to upgrade, but the newer product (even if used) should still be fully supported, or you really are no better off...

    ----------
    After a closer look at the parts list (the service manual does not note different drive cases), the jet units are NOT the same between the two horsepowers (they are each unique to fit the powerhead base) - so while you might be able to jury rig a drive housing (if they were still available - and sold for about 600 bucks when they were - and that's just the plate that would allow the powerhead to be mounted on the jet) you would really end up with a "franken-jet".

    So if you want a 120 you need everything - nothing but another 90 will go on your existing jet unit unless you want to do some looking for parts and retrofitting the drive..
    Last edited by galamb; 07-20-2010 at 04:50 PM. Reason: additional information

  3. #3

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    Basically all i am trying to do is get rid of the problems with always losing spark due to something in the ignition going bad. My grandfather owned this boat before me and every summer he was replacing something in the ignition. I now have the boat and it is getting no spark. I would really rather just change out the entire ignition but cant seem to find a kit anywhere. I bought a red stator but it seems i am missing something to actually hook it up. I have a DVA meter to test ignition parts but rather than test and replace with older outdated parts just to have it fail by next summer i would rather spend the money and fix it for good. The motor itself was actually just rebuilt so the compression and carbs are great, just the ignition is troublesome. So if you could steer me to an entire ignition UPGRADE and not just replacement parts that would be great.

  4. #4

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    I have a 90 sport jet 120 engine I want to convert to something that will be able to get parts and be able to install a engine an updated version. Or is it not worth doing

  5. #5
    Join Date
    May 2007
    Posts
    9,267

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    Not quite sure what you are after here.

    The 90 sport jet (with the 120 horse powerhead) is now pretty much orphaned. There are some parts out there for them but they certainly are not actively supporting them anymore.

    Additionally, Merc now only makes one "sport jet" that resembles the style you have - it's a 200 horse model built with an Optimax (direct injected 2 stroke) powerhead.

    It is considerably more powerful than a typical "jet", only losing 10-15% of it's (engine) horsepower. So while a 200 horse powerhead on an outboard style jet might end up with 130 or 140 horses (equivalent) at the prop/jet, the sport jet retains about 180'ish horsepower (equivalent) - minimally double what you currently have.

    So maybe not something that would suit what you currently have.

    I am unaware of any other product that would "swap in".

    Now, could you get a new powerhead from perhaps a 4 stroke outboard that could be jury rigged to work - if you spend enough money you can probably get anything to work.

    But the "short answer" to your question is - NO, there is nothing currently available as a "drop in" update to what you have. The cost of "updating" could well cost double the current value of your whole rig.

    You have an orphan that Merc decided not to adopt....
    Graham

    A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

  6. #6

    Exclamation Will a 1993 Sport Jet 90 motor adapt to a 1997 Jet Drive (F16)?

    I recently purchased a project 1993 Sea Rayder with the 90hp motor. After beginning to disassemble the engine components to remove the engine, I have realized there are many missing components. I have located a great donor boat which is a 1997 Sea Rayder. The 97 does not have the motor but has a NEW Jet Drive that was intended to replace the original (which connected to the F16 120hp motor). My question is, will my 90hp motor adapt to the new jet drive? I'm not interested in opinions of the 90hp vs the 120hp motor. I just want to know if my motor will adapt to the new jet drive. I don't know if the 1993 has the spline shaft or screw type because I haven't broken it down that far yet, But the new drive in the 1997 boat has the spline type.

  7. #7

    Default Re: Will a 1993 Sport Jet 90 motor adapt to a 1997 Jet Drive (F16)?

    Quote Originally Posted by craigsawyer75 View Post
    I recently purchased a project 1993 Sea Rayder with the 90hp motor. After beginning to disassemble the engine components to remove the engine, I have realized there are many missing components. I have located a great donor boat which is a 1997 Sea Rayder. The 97 does not have the motor but has a NEW Jet Drive that was intended to replace the original (which connected to the F16 120hp motor). My question is, will my 90hp motor adapt to the new jet drive? I'm not interested in opinions of the 90hp vs the 120hp motor. I just want to know if my motor will adapt to the new jet drive. I don't know if the 1993 has the spline shaft or screw type because I haven't broken it down that far yet, But the new drive in the 1997 boat has the spline type.
    No it won't. One is 13 spleen. And the other is 15. Also the jet drive impeller shaft is different only difference inside gear is milimiters larger on the 120hp besides the speel numbers

  8. #8

    Default Re: Will a 1993 Sport Jet 90 motor adapt to a 1997 Jet Drive (F16)?

    Im facing the same issue. Trying to install a 98 mercury force outboard inside a 90 sport jet drive. It fits and they are basically the same motors besides minor differences. Different flywheel, different ignition system, different crankshaft spleen 13 vs 15. Yes the motors will only give 90 hp because that's all you gonna get from the jet drive. But !!!!!!!!! Force outboard has neutral and jetdrives does not as its always spin designed that way. Im having hard time starting it. Starter jams after one turn. Now noticing the flywheel not centered
    I removed the fuel to eliminate flooding
    I added extra ground to the starter
    I ordered a starter and its on its way. Voltage drops from 12.5 to 9v when jamming
    Im still wondering if the jet drive is preventing it from starting , I have the jet open to the impeller and it does not get stuck, well I go with new starter if it don't work then lower the jet drive.
    Anythoughts

  9. #9
    Join Date
    Sep 2010
    Posts
    22,827

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    These jet boats were marketed for a period of about 4 years.----Not factory supported anymore.

  10. #10
    Join Date
    Sep 2010
    Posts
    22,827

    Default Re: Sport Jet 90HP 1994 swap to a newer motor?

    Many jet boats have been tossed into land fill.----On option is to convert to just an outboard motor.-----Sawsall required.

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