RESTO Rotax 587/717 Intake+Carburetor Compatability

[TicTacZac]

I’ve tried to search for answers but I apologize if I shouldn’t be creating this new thread.

I have a 717 running a dual carb BN-38 setup. I also have a 587 with the single BN-38 carb setup. The single carb intake off the 587 bolts perfectly onto my 720. My question is, will this work and what single carburetor is required to run my 717?

I have read the later single carb 717 engines ran the BN-40I. Thanks in advance for any help.

 

[TicTacZac]

Here is a picture of the single carb intake off of my 587 bolted on my 717.

 

[chipskittles]

The jets are different on dual setups vs single setups with the 717s. The rotary cover openings are a little larger on the 717 vs 587 as well. I would think you could make it work but it will probably want to run lean. Maybe you can compensate with jetting?

 

[etemplet]

Just a question, why do you want to swap intakes??

 

[chipskittles]

Just a question, why do you want to swap intakes??

I bet the answer is 587 parts are cheaper!

 

[TicTacZac]

Well I’ve read there isn’t too much power loss with a single carb 717 vs the dual carb setup. I wanted to throw a single carb intake on the 717 to make my life easier, I’m terrible at tuning 2 carburetors on one engine.

 

[TicTacZac]

The jets are different on dual setups vs single setups with the 717s. The rotary cover openings are a little larger on the 717 vs 587 as well. I would think you could make it work but it will probably want to run lean. Maybe you can compensate with jetting?

Just for or clarity, which jets are different? Jets on the carburetors or ports on the engine itself? Thanks!

 

[mikidymac]

On a 717 the dual carb and single carb engines make the same 85HP. The carbs on the duals are 38mm and on the single it's a 40mm. Jetting is obviously completely different.

 

[TicTacZac]

On a 717 the dual carb and single carb engines make the same 85HP. The carbs on the duals are 38mm and on the single it's a 40mm. Jetting is obviously completely different.

Oh okay now I feel silly. Other than jetting, do you think I’ll run into any major issues?

 

[chipskittles]

Well I’ve read there isn’t too much power loss with a single carb 717 vs the dual carb setup. I wanted to throw a single carb intake on the 717 to make my life easier, I’m terrible at tuning 2 carburetors on one engine.

You are not alone. I thank my lucky stars Sea-Doo decided to drop them with the 97 boats. It's doable to use what you have to make a single setup you will just need to change the jetting to something around what the singles came with but I have only done it with 587s.

 

[Matt Braley]

You will need the correct 717 single carb intake manifold. The single carb 717 setups run good but they take different throttle and choke cables. That 587 intake manifold bolts on but has smaller ports in different places (as mentioned before). The 717 takes a I-body style carb that bolts on differently.

 

[chipskittles]

You will need the correct 717 single carb intake manifold. The single carb 717 setups run good but they take different throttle and choke cables. That 587 intake manifold bolts on but has smaller ports in different places (as mentioned before). The 717 takes a I-body style carb that bolts on differently.

I want to say you can reuse the choke cable you just have to shorten the shaft at the end of the cable since it only has to go thru one carb not two The single carb choke cable setup is different yes but the dual carb setup can be made to work.

 

[Matt Braley]

The single carb setup does not use the shaft that gets clamped with a set screw. They have a barrel at the end of the cable.

 

[TicTacZac]

I want to say you can reuse the choke cable you just have to shorten the shaft at the end of the cable since it only has to go thru one carb not two The single carb choke cable setup is different yes but the dual carb setup can be made to work.

Fortunately I have already done this because I ripped the 717 out to run my single carb 587 last summer

 

[chipskittles]

The single carb setup does not use the shaft that gets clamped with a set screw. They have a barrel at the end of the cable.

Right I was just saying if one wanted to reuse a twin carb, while not ideal,you could make it work without a new choke cable.

 

[TicTacZac]

You will need the correct 717 single carb intake manifold. The single carb 717 setups run good but they take different throttle and choke cables. That 587 intake manifold bolts on but has smaller ports in different places (as mentioned before). The 717 takes a I-body style carb that bolts on differently.

Thank you for the help, sounds like I’ll be on the hunt for a 717 specific single carb intake.

 

[chipskittles]

Thank you for the help, sounds like I’ll be on the hunt for a 717 specific single carb intake.

They are the desirable intake so tend to fetch a higher amount than the duals but there are always deals just be patient. I just got a spare singe carb with intake and oil pump, rotary cover and all yesterday for way less than people get for just the intakes.