Merc sport jet 120

[Mike dauby]

hi everyone (I’m a vergin to this site) I am in a bit of a spot right now. I purchased a sea ray F16 with a sport jet 120. It was not running and I figured I’d have to rebuild the engine. Naturally I now need a rebuilt unit because there is a hole in the block right behind the computer plate so I couldn’t see it till disassembling. Anyhow I am looking for a rebuilt sport jet 120 is that the same as a force? I know the force is an outboard power head but will it work on my jet drive? Any help would be soooo helpful! Let me know if you have an engine! Thanks in advanced! Mike

 

[Cobra Jet Steering LLC]

Get with @RedBarron55 he has been dealing with one of those engines so he may have some info

 

[Cobra Jet Steering LLC]

it is basically a force outboard however red barron discovered some important info that will be helpful if he looks for a force engine to replace his power head so this is who I would suggest he speak to and save himself some grief.

 

[Mike dauby]

Awesome how do I speak to him? I searched his name and saw some posts but I didn’t see how to message him directly. Thanks so much!

 

[Cobra Jet Steering LLC]

click on his name and send him a private message via START A CONVERSATION

 

[RedBarron55]

My boat is a 90 hp and I am afraid I can't help much with a hole in the crankcase behind the computer.
This would be around the #1 or #2 cylinders and would strongly suggest that the engine lost a con rod.
A replacement bloc and crank would be necessary at the least along with the internals.
The power head is basically the same for the outboard and the l-drive and the jet, but with one major difference, the crankshaft splines are different between the outboard and the (L-driven and jet).
Basically you need an engine with the right crank and the outboard will not work, but the crankcase would work.
You can look for a rebuild or low time engine and also pull the engine and check to see of by some chance the crankshaft survived as it is the hard part to come by.
If you were very lucky the crank could be good, but I would not hold my breath on that one.
Parts can be found on ebay and rebuilt can be found

This motor might be correct, but the shown exhaust manifold cover is wrong as is the base adapter for the jet.
If the crank is correct it could work.
The base and manifold cover could be swapped with yours
https://www.ebay.com/itm/Force-Mercury-outboard-120hp-powerhead-4cly-1996-to-99-block-head-sportjet/122950094994?hash=item1ca0659092:g:TmMAAOSwjRpZUrVr&vxp=mtr

Here is one dressed, but still has the fittings for an outboard, but the key is the crankshaft splines to fit the Jet.
https://www.ebay.com/itm/Force-Mercury-outboard-120hp-powerhead-4cly-1996-to-99-block-head-sportjet/122950100248?_trkparms=aid=222007&algo=SIM.MBE&ao=1&asc=49917&meid=7e2c795c139945189711bc8f439cf8ee&pid=100005&rk=1&rkt=6&sd=122950094994&itm=122950100248&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/Force-Mercury-Sportjet-Sport-Jet-90-120-hp-Engine-Motor-Block-Cases-95-96-97-98/173134686089?hash=item284fa1a789:g:8zsAAOSwqfZac3v6&vxp=mtr

https://www.ebay.com/itm/Force-Mercury-Sportjet-Sport-Jet-90-120-hp-Engine-Crankshaft-Crank-95-96-97-98/173132309810?epid=2285179807&hash=item284f7d6532:g:W4YAAOSwXzNachfi&vxp=mtr

Sometimes it might be easier to find a boat with a rebuildable engine and a sad hull.

Your situation is my biggest fear with my Sport Jet 90 Hobie Jet so I feel for you.

 

[Mike dauby]

Thank you so much for all your help! Yea I never though it was going to be this hard to even locate an engine so I appreciate your help a ton! I found a place that can get me going but it’s almost 3k and I have to mix my fuel myself from now on (I’d rather do that anyhow)

 

[RedBarron55]

It is likely that the rod was thrown because of an oil injector that was not working for some reason.
My 90 hp is not oil injected and I mix.
While it will smoke more and be a PITA you will know that you have oil!
By the way a fuel filter/separator might well be a good addition as well.
I also have a clear filter between the fuel pump and carbs so that I can see the fuel and if there is water in it too.
For $3K I hope that there is a warranty as well!
Be sure to check the oil in the pump both the front gearbox ans the stator too.
When you install the motor make sure that the adapter base has the correct gasket and replace the O rings at the adapter to pump locations One for the cooling water and the other to seal the crank to gearbox connection.
Gaskets are mostly common between the outboard and Jet but NOT the exhaust manifold and the base for sure.
The seller might send gaskets but MAKE SURE THEY ARE THE RIGHT ONES!

 

[Mike dauby]

Yea it is a 1 year warranty and all gaskets are included with shipping. Makes me sick to pay that much but I’m about out of options so right now it’s the best option haha. Yea I will be replacing all gaskets cause I do not want to have to repeat any of this! Thanks again!

 

[RedBarron55]

Correct Gasket

Wrong gasket that was installed in my boat with rebuilt engine by the previous owner.
The Exhaust gasket that is correct is thicker as well I think...

 

[Cobra Jet Steering LLC]

I need to ask you in all honesty do you really think this boat is worth putting that sort of money into? one in running condition off N A D A with a trailer
Values are between 2900 and 3300 depending on the condition it sold for 9900 new just a heads up on it I believe people were installing the v6 mercury engines and pumps in those hulls. I believe @Ben Okopnik has one of those

 

[RedBarron55]

I have to agree These boats are cheap because they are relatively unloved.
I spent the time and money on my boat because it is a Hobie Jet Skiff and will be great for fishing in the Santa Rosa sound and shallows.
I don;t know how much you paid for the boat with a blown motor, but it is your choice how to spend your money.
Personally nowadays the jet boat builders are putting the OptiMax 200 Sport Jets in specialty hulls and they say that it is the best deal going with cost and economy.
Personally I know that the 90 Sport jet is a fuel sucker, but in my case the fuel cost will be a small thing.
That and I am retired and need a hobby to keep me busy and outta sight for other chores from She Who Must Be Obeyed.
I paid $2000 for the Hobie Jet Skiff and Continental trailer and have another $1000 in travel to fetch it and get it going.
The book value would be probably $2500 - 3500, but you can't take it with you, but you can fish with it.