SL750 queries

[Skexies]

I have just purchased a '95 SL750 and am curious if anyone has "knowledgable" information on what configurations are good for this PWC. [ Yes, I saw group k's list ;) ]

I figure with how long it has been around, there must be some 'tried and true' mods around.

As a note: I'm more of an acceleration nut, than pure top speed junkie. I also, only live around lakes... so water is at most moderately choppy but never cresting waves.

Thanks,
-Eric

[Lenchmob]

Hey Skexies. I also have a 1995 polaris sl750. I recently had to put a new sbt motor in it because of a lil accident at the beach. There is not that much stuff out there compared to sea doo stuff. I just put prok flame arrestors and had the carbs reworked and tweaked. I also put a jetlyne water box and a r&d intake grate on it. I have only rode it for about 20 minutes since I did the mods because of weather and work. The only other thing I am going to do is put a solas prop and ride plate on it. All the parts I got out of the Dennis Kirk catalog. Maybe SeaLion will respond to your post. He seems to know a lot about polaris. Hope this helps you out a lil.

[raider1100]

Heres a tip for you guys who had polaris skis. When i worked at this shop I would always do this to ALL polaris skis. except the new Fitch fuel injection

On the gas supply line on the skis between the carbs i would install 2 tee connectors.
One to go between the #1 & #2 and one to go between the #2 & #3. then i would run another t from the gas supply line with 2 lines to connect to the 2 t's I just installed. Now cap off the original gas supply nipple or you can run a 3 way from the fuel supply ( 2 for the T's you installed and one line for the original fuel nipple. I know you can get another fuel pump and do it that way, but this way works also.

The problem with polaris is they always fuel starved the cylinders. I do it to basically all my triple cylinder skis.
Also another thing you can do is to get a degree shim for the pump. i think they come in 5 degrees. and install it on your ski. it would make the top speed a little faster, but it will porpose more. so youll have to get a different ride plate
Also another thing to do is to have the stock exhaust pipe sent to a Extrude Hone type of place where they push this mud substance through the pipe and it makes it perfectly smooth. it does remove some material. i did it to my raider. the only thing its kinda expensive i think it cost me 350, but nobody makes a pipe for my raider so it wasnt really that much.

[Bryan Glynn]

<BLOCKQUOTE>quote:</font><HR>Originally posted by raider1100:
On the gas supply line on the skis between the carbs i would install 2 tee connectors.
One to go between the #1 & #2 and one to go between the #2 & #3. then i would run another t from the gas supply line with 2 lines to connect to the 2 t's I just installed. Now cap off the original gas supply nipple or you can run a 3 way from the fuel supply ( 2 for the T's you installed and one line for the original fuel nipple. I know you can get another fuel pump and do it that way, but this way works also. .<HR></BLOCKQUOTE>

That doesn't exactly solve the problem. The problem with most Polaris triples is fuel starvation, but not from the supply - from the output of a single pump. In the stock series configuration, the #3 and #2 carbs get adaquate fuel supply, while the first does not. So much so that a hole usually burns though the #1 piston. If you run the output in parallel instead of series, you are just lessening the supply to both the #1 and #2 carbs, just by a lesser extent than #1 in stock form. While it may be below the threshold, it may also go above, and then you would have problems in BOTH #1 and #2 cylinders, not just #1. You're going from supplying #3:100%, #2:100%, #1:70% to #3:100%, #2:85%, #1:85%. The only real fix is to add another pump to supply 100% to all carbs. A single pump just can't supply that much fuel, no matter how you plumb it.

[ April 03, 2001: Message edited by: Bryan Glynn - SBT Webmaster ]

[UniBougie]

Hi Skexies,
I just picked up a '95 SL 750 for a steal, 73 hours on it. I was lucky enough to stumble across a service manual. I'm doing top-end rebuild. Found a Wiseco Kit @ DCT for $237 + bearings. I Put in a R&D AquaVein and am waiting on a Ocean Pro rideplate. I'm pretty sure I'll add the second fuel pump. Where to mount it? I'll be chaging all the rubbers and saturating cables, nuts, bolt and clamps with lube. Hope to have it in the water in 10 days. Can't wait
I'll see how the ride go this year and think about more mods later. I think the next step would be F/A's, primer and dialing the carbs in.

Later

[ April 04, 2001: Message edited by: UniBougie ]

[UniBougie]

Bryan,
If I have to use a second pump, why not T in between #1 & #2? Does it create a problem if #2 is fed two pumps? Can that little single Mikuni pump handle that?

Has anyone used any CCS(http://www.choppercity.com/) products? I have been debating a 4* wedge.

[ April 04, 2001: Message edited by: UniBougie ]

[ April 04, 2001: Message edited by: UniBougie ]

[raider1100]

Well Bryan Im sure that a second pump would be the better way to do it, but wouldnt that mean you need a second fuel pick up? and all related hoses and possibly gas tank mods. I mean if youre just gonna add another pump to the existing line youre still basically getting the fuel from one fuel line.
As for the way i used to do it it worked and we didnt get skis back with melted pistons. personally I think its more of a fuel starvation because by the time the fuel gets to #1 its already gone through #3 & #2.
What this does it basically gets fuel to all 3 cylinders at about the same time instead of the #2 and #1 waiting for the fuel to get to them. I guess its more of a poor mans fix.Another thing is to mabey switch to a bigger pump from a 1100 or 1200 motor. that should flow more fuel, and this way you could possibly run a larger gas line to supply the fuel. What do you think?
Rob

[Bryan Glynn]

<BLOCKQUOTE>quote:</font><HR>Originally posted by UniBougie:
I'm pretty sure I'll add the second fuel pump. Where to mount it? <HR></BLOCKQUOTE>

I just mounted three in a 750 here at work - I zip-tied them to the existing zip-tie mounts on the hull right next to the carbs.

[Bryan Glynn]

<BLOCKQUOTE>quote:</font><HR>Originally posted by UniBougie:
Bryan,
If I have to use a second pump, why not T in between #1 & #2? Does it create a problem if #2 is fed two pumps? Can that little single Mikuni pump handle that?<HR></BLOCKQUOTE>

Because the point is to eliviate the load off the original pump and allow the #3 and #2 carbs to have 100% supply off it. By plumbing the second pump only to the #1 carb, you assure that. Theoreticaly you can just t-into the lines anywhere, but frankly it just makes it more complicated than it needs to be.

[Bryan Glynn]

<BLOCKQUOTE>quote:</font><HR>Originally posted by raider1100:
Well Bryan Im sure that a second pump would be the better way to do it, but wouldnt that mean you need a second fuel pick up? and all related hoses and possibly gas tank mods. I mean if youre just gonna add another pump to the existing line youre still basically getting the fuel from one fuel line.
As for the way i used to do it it worked and we didnt get skis back with melted pistons. personally I think its more of a fuel starvation because by the time the fuel gets to #1 its already gone through #3 & #2.
What this does it basically gets fuel to all 3 cylinders at about the same time instead of the #2 and #1 waiting for the fuel to get to them. I guess its more of a poor mans fix.Another thing is to mabey switch to a bigger pump from a 1100 or 1200 motor. that should flow more fuel, and this way you could possibly run a larger gas line to supply the fuel. What do you think?
Rob<HR></BLOCKQUOTE>

No, you don't need more than one pickup. No stock skis come with more than one, and it's not needed at all. Even the big Yamaha 1200's with triple pumps only have a single pickup. The only time you need separate pickups are on VERY high flow race skis.

Replacing the single stock pump with a high-flow would also solve the problem, yes.

[UniBougie]

Hey Bryan,
I hear ya. I was just thinking that since you have 2 pumps, why not maximize their use. I thought it would be a good back-up if the the #1 pump failed. The second pump could handle the load. But then I guess you end up back at square 1 and I haven't heard about many of those pumps failing. I'm sure it happens but I just haven't heard about it. But I get your point, about over complicating things.

Thanks for the info

[Skexies]

UniBougie,

That is where I am at... I don't know the efficency of either pump, I do know that one is 6 years old, so I'm throwing brass tees between 1 & 2 and 2 & 3.

I'm even going a bit more excessive, in that I'm bringing feeds from those tees out to form a loop with two more tees placed below the two pumps mounted on the wall. The stem of each second Tee gets fed from one pump output. This, in theory, would equalize the flow pressures seen by all 3 carbs. [ACE Hardware sells 1/4" brass tees that I can't seem to find at lowes or hdepot ;)]

The only reason I have found NOT to do this... is that off-idle may not be as smooth. Longer lines take longer to pressurize and at idle / just off idle there is not much displacement [volume] being pumped from the fuel pumps to compensate for higher fuel demand.

Take care,
-SEF [img]smile.gif[/img]

[ April 09, 2001: Message edited by: Skexies ]

[Skexies]

UniBougie,

Also... Hotseat performance has some nice things. You might want to check them out.

Look at group-k and their list on the 750 mods. [www.groupk.com]

You might wanna check out Carbon tech reeds (i'm sure the old ones are tired), the 4" extended pump from the SLX, the SLX ride plate, and the R&D scoop. [scoop is supposed to balance the speedo error incured from the pump change]

I'm also tossing on an R&D pro-lock flame arrestor, a set of 44/40mm Mikuni carbs, and mabey a pipe from the 650 (if it all works ;) ).

Eventually, I'll swap out the top end for a 780, group k suggested that they should bolt up on the 750 bottom end.

I also understand that you can stand to run "8"'s for plugs instead of the "7"'s run factory default.

Bryan can hook you up with the carb rebuild kits and the oil block-off plate if you want to go pre-mix for longevity and of course... you'll want to make sure you have a second fuel pump. ;)

Take care, and feel free to e-mail with questions!
-SEF

[ April 10, 2001: Message edited by: Skexies ]

[UniBougie]

Hey Skexies,

I see your logic. I decided to go another route, the shortest route. I am running pump #2 (the little rectangle mikuni) directly to number one cylinder and sending #1 (round mikuni) to number two & three. Hoping that if there would be a distribution problem or failure the engine would just run like crap or die before I burn or sieze a piston.
The only length I'm adding to the pulse line is the "T" and the shortest length to the #2 fuel pump. Hoping that will help offset the pressure problem but I’m adding length to
to everything, so I’m not sure about that idea but we'll see soon enough.
I just finished assembling the top-end (cylinders honed, wiseco piston kit, needle bearings, lube, everything washed up, flushed, resurfaced and some paint) looks like an new engine. I’ve got good clearances, good compression and strong lectricity.
I was wondering where I was going to mount the fuel pumps or second pump. Until I make make a bracket their bothhanging from the original mount. I thought that would help in keeping the added lines as short as possible.
I’m going to start working on the fuel and oil delivery tomorrow. R&D grate is waiting for the OP Rideplate to arrive.
After that we hit the water. If I have no other problems in the next couple of months I'll think about what's next.

Later,
UniBougie

[UniBougie]

People we have ignition!
Wooooo! Changed filters, bled the oil pump & lines, bled the fuel pumps, a little lube in the cylinders, add spark plugs, check those hose clamps!, pull the choke and turn over 1sec, 2sec,...7sec. We have combustion, steady now,smoothes out, turn on the water amd add a couple of low revs and Presto Chango smooooth idle. A couple more low revs, turn off the water and with assistance fog, a couple more short revs to remove the water and Fini! In a couple of days we move to the water for some break in cruising.

Later
UniBougie :D