1998 seadoo sportster engine swap help needed

[Russellbugg007]

Hi all. So doing a engine swap on my 98 sportster 1800 twin 720’s , I got a engine from a 97 seadoo hx 720, was told they are all the same, but I don’t think they are. The carbs are a bit different And block, so the 98 1800 has a fuel pump with 3 hoses on it, 1 from the tank to pump, 1 from pump the carb , and another 1 from the pump to the block just behind the mag on carb side . The 97 hx 720 dose not have this, but rather A hose comming off the carb and into the block at the PTO carb side of the engine . Anyone know what I do with this ? Or what the hose comming off the pump to the block is ?
thanks

 

[racerxxx]

So the fuel pumps are divorced from the carbs. You can use the block of plate on your current carbs. The return line is almost different, again, you just need to run it out the rear and not out the front. But, they will all work.

 

[Russellbugg007]

So the fuel pumps are divorced from the carbs. You can use the block of plate on your current carbs. The return line is almost different, again, you just need to run it out the rear and not out the front. But, they will all work.

Great thanks for the tip and reply. . I am kinda new so you mean I can block off the line comming from the carb to the block ? Easy as that? Run the hose comming from the pump to the back of the block ? .

 

[racerxxx]

The 3 lines are fuel from tank, fuel to carb and pulse. The pulse is the one that connects to the engine. You need all 3

 

[Russellbugg007]

The 3 lines are fuel from tank, fuel to carb and pulse. The pulse is the one that connects to the engine. You need all 3

Ok thanks, how do I get rid of the line from the carb to the block ? Can I just block it off ? Thanks for all the help.

 

[racerxxx]

No you need that, that's what makes the fuel pump work. That's the pulse line. Post a pic so I'm sure we're on the same page.

 

[racerxxx]

Why don't you just rebuild the carbs in the old engine and run those so everything is the same?

 

[Russellbugg007]

Why don't you just rebuild the carbs in the old engine and run those so everything is the same?

I gave the whole thing away to rebuild, carbs and all because I had this donor ski I could use for the rest of the season, did not know about this pulse line thing .

here is a pic, u can see blue line from carb to block, and gray (changing it) line from pump to ????? supposed to be block...

 

[FlyboyX]

the line you have in your hand in that pic is the old school grey line that disintegrates with alcohol blended fuels. you definitely need to replace that. the lower hose that you have circled in yellow is your pulse line. i am guessing that carburetor doesnt have an internal fuel pump. i guess you can make it work by hooking the pulse line from the crank case to your external fuel pump.

really sucks that you already got rid of your old motor. i guess if it were me, there is no way i would have parted with anything until i was done with the project. lesson learned i guess.

 

[Russellbugg007]

Ya I should’ve kept everything my buddy made it seem like it was an exact simple switch, lol lesson learned, and yes I am changing this grade line, so the line coming out of the block that I have circled in yellow woth a blue hose goes to the carburetor, do I split it and run to both fuel pump and carb ?

 

[s022mag]

I'm working on the same thing, swapping a bad motor with a used motor. The newish one looks to have a block off plate where the oil is injected, I was hoping to just remove the whole setup and put mine in its place.

 

[Russellbugg007]

I'm working on the same thing, swapping a bad motor with a used motor. The newish one looks to have a block off plate where the oil is injected, I was hoping to just remove the whole setup and put mine in its place.

You can use the pump from your old engine.. if u need a pump I just removed mine and went premix . I'm in ajax

 

[s022mag]

You can use the pump from your old engine.. if u need a pump I just removed mine and went premix . I'm in ajax

I thought about removing both mine from each motor and going premix but I heard that the gas injectors weren't designed to push both gas and oil mixture through the same jets...

 

[Russellbugg007]

Ya I have read the same thing. I may try for bigger jets next time I rebuild the carb.. but so far no issues.

 

[s022mag]

I'm wondering if that was what cause my engine failure was the oil injectors, so I thought of running a little bit of premix as insurance. Are the rebuild kits difficult?