Upgrade Sea doo Explorer 717 to 787 or larger

[Armysinger]

Hello all from forum newbie. Hoping to get some experienced / advice for both myself and to give to my mechanic. My 717 needs a refreshing. I'd much rather put the $800 towards a bigger engine than keep struggling to get on plane fully loaded.

We absolutely LOVE this Explorer and have had wonderful times as a family the last couple years. Still have younger kids and want to keep this around as long as possible.

As you can see from pictures below, there is not much room in the Bilge. Would love the 951, but not sure if that's possible...... 150mm pump, exaust, ect.

I don't have doner boat yet, but want to start looking so work can be done this winter...(rate lower and more time available) [emoji6] Is the extra work for the 951 worth the additional 20 HP. I'm fine spending a bit more for a better long-term solution if it is possible.

We use our explorer as our runaround boat and for wakeboard, tube, weenie, and airchair. Have kids from 2 to 17 so want a good long-term solution. It's nice to have room to throw 5-6 kids in....and much safer.....will NEVER roll.

Right now with the 717, were pretty much always WOT. Already dropped impeller pitch to help with hole shot.

Oh....and if Christmas could come everyday of the year, I would LOVE to have enough power to flyboard 5-10'. Not the 30-40 that new pwc can deliver, but enough to give the older boys eternal smiles. [emoji16]

Please lend me your suggestions and advice

 

[hotrodssnova]

The 787 has a completely different foot print when it comes to bolting in. It has 3 motor mounts, no engine pan (that black plate at the bottom), would need a different computer (mpem).

So, in short, it would be easier to find a different boat. Is it impossible? No. Just some fiberglass work, wiring, and maybe new cables.
A new engine will wake up a boat. The 720 you have might be tired. Do a compression test, check to make sure the wear ring is not worn out.

 

[Armysinger]

The 787 has a completely different foot print when it comes to bolting in. It has 3 motor mounts, no engine pan (that black plate at the bottom), would need a different computer (mpem).

So, in short, it would be easier to find a different boat. Is it impossible? No. Just some fiberglass work, wiring, and maybe new cables.
A new engine will wake up a boat. The 720 you have might be tired. Do a compression test, check to make sure the wear ring is not worn out.

Hotrodssnova, Thanks for the comments. Compression is 115 and 105. It is definitely tired. Just hoping to get more than the 85HP the 720 will deliver. Would Bore and new sleeves ect be safe and long-lasting if an engine swap is not in the cards?

 

[hotrodssnova]

Sometimes that works. Sometimes the crank will let go. Kinda hit or miss. If it has a bunch of hours on it, best to do the whole engine. With that compression, it's no where close to the rated hp now.

 

[snikwad003]

Some of the hx guys put a kawasaki 1100 3 cylinder in their skis with a engine cradle of some sort, never seen one in person only read about it. I would rebuild the 720, its proven to you to be a solid motor and you wont have some custom stuff to scratch your head about later

 

[mandriva]

Yes, the compression is tired...150psi is right compression...
But what you need ?more holshot or top speed?because the 720cc is the best motor reliable ever build by bombardier
You could put flames arrestor and raise the compression to 165 and put rossier pipe (8hp) you will get 95@ 100hp.... But you need run 93octanes
Do you want run 93octanes?

 

[Armysinger]

Yes, the compression is tired...150psi is right compression...
But what you need ?more holshot or top speed?because the 720cc is the best motor reliable ever build by bombardier
You could put flames arrestor and raise the compression to 165 and put rossier pipe (8hp) you will get 95@ 100hp.... But you need run 93octanes
Do you want run 93octanes?

Thanks Mandriva. Hole shot is most important. I have already dropped prop pitch. Have to check the numbers on prop. Top speed empty is ok (25-28 mph), but once we get 800 lbs in, speed is cut in have....if we eventually get on plane. Any concerns for adding different exhaust? Anything else I should be aware of by "beefing up" the 720?

 

[Armysinger]

Thanks Mandriva. Hole shot is most important. I have already dropped prop pitch. Have to check the numbers on prop. Top speed empty is ok (25-28 mph), but once we get 800 lbs in, speed is cut in have....if we eventually get on plane. Any concerns for adding different exhaust? Anything else I should be aware of by "beefing up" the 720?

Also, I'm,already running prelium (91). I guess I would be ok running 93. Haven't thought about that as yet. What are the drawbacks?

 

[snikwad003]

Keep in mind your boat is heavy compared to a jet ski so addding a few hp for a bunch of money might not get what you want, and your fuel consumption will go up quite a bit. If you are serious about this project I would go with a 787 swap and leave that motor stock @110 hp and experiment with props and nozzles. A carbed 951 would be good too but you might not get its full potential with out the 155mm jet pump, if you do swap a 155mm pump the intake tunnel might not provide enough flow for the larger pump based on what I have read about 951 swaps in hx's.

 

[Armysinger]

Keep in mind your boat is heavy compared to a jet ski so addding a few hp for a bunch of money might not get what you want, and your fuel consumption will go up quite a bit. If you are serious about this project I would go with a 787 swap and leave that motor stock @110 hp and experiment with props and nozzles. A carbed 951 would be good too but you might not get its full potential with out the 155mm jet pump, if you do swap a 155mm pump the intake tunnel might not provide enough flow for the larger pump based on what I have read about 951 swaps in hx's.

In feeling the same way about the 787. My mechanic guy feels the 787 is the best option as well. Thinking of refreshing my current 720 anyway and seeing what that difference makes before I spend $ on the 787 swap. I might be able to get most that $ back anyway when selling . any thoughts on the Kawasaki 1100? Which swap would be easy 787 v 1100

 

[mandriva]

Also, I'm,already running prelium (91). I guess I would be ok running 93. Haven't thought about that as yet. What are the drawbacks?

Put only rossier, factory pipe is race pipe and she eat piston for diner....so this solution is cheap..but you will better holeshot and mid range...what is your impellor picht? You really need skat trak swirl!!

 

[snikwad003]

on the 787 except for fiberglassing new engine mounts every thing fits like its ment to be there including the entire drive line, with the kawi its alot more to it

 

[Armysinger]

Put only rossier, factory pipe is race pipe and she eat piston for diner....so this solution is cheap..but you will better holeshot and mid range...what is your impellor picht? You really need skat trak swirl!!

Good call on the skat trak. My guy already put one on. Can't remember pitch though. I'll ask and report back. What benefits will be gained with a rossier pipe along with the down-sides?

 

[mandriva]

5@8 hp...matt already try..i have the catagolue with dyno