08-05-2008, 03:08 PM #1
Adding Pro785 parts to SLX780, need some info...
...ok, as you know, I have a '96 SLX780. Actually, I have 2 now, I just have to go get the 2nd one. Anyway, I want to add the Pro785 triple-pipes and exhaust-valves, but am unsure what all I will need to do to add them. I know I will have to retune the carbs, but what else will need to be added/changed/retuned? Do I need the 785 CDI box? Do I need them, or will I benefit from adding the 785 reeds? What about the impeller, will I need a new one? Basically, all I really want to run are the Pro785 triples and exhaust-valves, so any help you can provide will be greatly appreciated.
Also, would it end up being cheaper and easier to just buy a nice Pro785? If so, what year is the best year? Thanks in advance...
08-05-2008, 03:10 PM #2
I assume you already have the pro 785 cylinders?
08-05-2008, 03:26 PM #3
- Join Date
- Aug 2006
- Homer Glen Il.
Your much better off buying a 785 for around 2000.00 or less and then your done !!!!!!!
much cheaper in the long run talk to Starlight and see how much he spent .
08-05-2008, 06:55 PM #4
That's kind of what I figured, might as well just pick up the whole ski.
Aren't the 780 and 785 cylinders the same, or at least close enough to run 785 triples on 780 cylinders?
08-05-2008, 07:23 PM #5
Not even close the 785 is a 750 bore the is stroked and has power valves.
08-05-2008, 07:25 PM #6
You could put a complete 785 set-up in the SL or SLT hull. The SLT will require some fiberglass
08-05-2008, 10:43 PM #7
Oh, ok...I was under the impression that the 785 was just a modified 780, thanks for clearing that up! Now I gotta find a nice Pro785...what is the best year?
08-05-2008, 10:54 PM #8
This is my project that you may want to check out. http://www.greenhulk.net/forums/showthread.php?t=43718
I certainly have more invested in my sl780 than it would have taken to get a pro785.
The 780 cylinders will not work w/ the pro exhaust valves. The pro cylinders have a slot machined into the cylinder above the exh. outlet that the 780s don't have. You just can't add 785 cylinders to your bottom end, and have a pro setup. The pro cyls. have a smaller bore, and the crank has a longer stroke. To use the pro cyls w/ the 780 crank, you would lose cc's and compression due to the smaller bore and more piston to head clearance.
If you were to throw a 785 into your hull, you would need the 785 cdi to run the electrical actuated exh. valves, unless you went w/ the pressure actuated valves. I think the 785 cdi is an upgrade to any fuji powered polaris, why not use one? It would give your slx a good kick.
Adding pro pipes to your craft is doable, but you would have 1 more issue to overcome than I did. That would be the fuel inlet on your boat. The pipe collector sits in the nose of the boat, and your fuel fill would need to be relocated. My 97 has a side fill, and was not a big issue. I had to buy a pro fuel tank and move it back and towards the starboard side a bit to get the clearance needed for the pipes.
I will say, I dont regret doing my project. It was fun, interesting and a learning experiance for me. I'm not finished fine tuning it yet, but I can say its a huge improvement on the excelleration. It had my 7 yr old son yelling slow down!!!, when I took him for his 1st ride on it. Last yr he didn't have a problem w/ its speed or excelleration. I will post some #s when I finish tuning it.
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