need advice on engine swap

[mikew15]

I just recently bought a 1999 seadoo GTX limited.I got this thing dirt cheep.It came from the factory with a carb 947/951 but the reason i got so cheep is because there was no engine in it.I have a 787/800 that came out of a 96 or 97 spx that im gonna put in.questions i have is related to the magneto cup.i just found out today that my gtx is a dual coil ignition and the spx was single.will a magneto cup from a 99 GTX 947/951 work on my 787/800?And if so how do i go about installing it (setting the timing).I aleady fiberglassed in the front mount and got a header pipe from a RFI to connect the exhaust.Thanks in advance

 

[SabrToothSqrl]

Let me know, how that works out, for you.

 

[LouDoo]

Interesting conversion, I think he magneto cup is going to be the least of your worries. You're probably going to need a donor ski for the electrics and wiring harness. The pumps are also different sizes.

Lou

 

[mikew15]

Electronics will work,just need to know how to time it.as far as the pumps go,i have both setups to try,i even have the plastic plate that the pump bolts to.(I work on seadoo,s as a second income)

 

[jammin777]

you are probably going to have to use a mpem for a 787 as well mainly for timing reasons, as for the mag cup someone that knows will chime in.
oops! Lou beat me to it. and agree about the pump.

 

[mikew15]

Its raining here and is gonna rain tommorow too,so it will probly be monday before i work on it,besides that my new magneto cup i bought off ebay wont be here till middle of next week.I thought abought putting in a 947/951 but the 787/800 is more reliable plus cheeper on gas.Ill try to get some good picts when i do this swap

 

[jammin777]

yes pics would be great! have fun!

 

[mikew15]

the electronics will work.i checked the timing advanc over at sea-doo.nets web site on the 2 engins and there very close.why does everone think i need to change the electronics?the plug is the same,checked the wiring diagrams and the 787 has a extra ground going to the stater where the 947 dont have it.stater for 947 and the 787 are the same part number,so why would the electronics not work?

 

[Matt Braley]

I've never heard of somebody doing quite what your attempting. I have heard of 951's running off an aftermarket 787 ignition with a cup from a 98XPL. Obviously you going the other way though. The timing would have to be checked with an automotive test light and adjusted (if need be) with a programmer.

You will have to have the 155mm impeller re-pitched though.

 

[Minnetonka4me]

If the 98 and 99 951s work with either system, the 787 should work just fine too. (changing the mag cups of course)

Id love to see some pix when you get done. I like that you used the RFI pipe that made things easy.

If you do any more swaps I have all these kind of parts in stock and ready to ship.

On the pump your gonna have to get a prop repitched, but it should work well once you get it dialed in.