gemiller

Finally deciding to do some engine work on my 550.

Current Specs:

All Stock rebuilt probably 3 years ago or so, running about 130 compression on each cyl give or take(it's what it was last year). No engine internal mods. Has a factory half pipe and an OP open intake. All other mods are handling.

I don't know enough about the different heads to pick a decent one for a stock engine. Just looking for a little extra get up and go without sacrificing reliability. This ski has been the most reliable thing I've ever owned and want to keep it that way.

Only reason I'm posting this is I'm going off the assumption that all the different heads are set up for different compressions and not sure what's the best to go to for a stock build.

Thanks ahead of time all you knowledgable folk.

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soonerkid

Due to your all stock engine you have a few options before buying aftermarket parts. If you are running a paper head gasket, you can up your compression by running a thinner copper gasket. Also, you might ask around for a used stock milled head. Someone would probably give you one for free. I might have one or can get one shaved if you want to go this route.
I will let the aftermarket gurus tell you about different heads...

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701 Square - with all the goodies

bkoche

The PJS heads are nice because they have a larger water jacket but you need longer studs to run them. Westcoast heads have changeable domes so that you can pick the dome set that gives you the compression that you would like but Ive heard stories of sealing issues with the domes and the head. The westcoast heads are kinda rare. Id trade my PJS head for one in a heartbeat because I have a lot of WC parts on my ski

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2004 SXR - FPP Wetpipe, Blowsion railcaps, 4deg bars, billet clamps
1994 750sx - Loaded -FOR SALE
1983 JS550 - WC RC520 reed cylinder, WC Head, PJS WB, Dual 38SBNs, WC 750 reed stuffers, WC Stacks, WC 6.5gal tank, FPP Halfpipe, SBT High torque starter, 16.5 Skat, Blueprinted 440 pump, lightened driveshaft, 76mm OP nozzle, Jetsport bulkhead brace, 90wt mod, WC scoop, Rend plate, Rear exhaust, Carbon Fiber

1991 Honda CB750
1976 Suzuki RE5A
1976 Suzuki GT750A
1975 Suzuki GT550M

550/440

The Ocean Pro swirl cut head was the best high compression head I ran on my old 550. I had 130 compression on it before I added the OP head, it bumped it up to 160, and it made a big difference in the amount of low end pull it had - I loved it. You don't mention an impeller in your mods though - that is the first thing you should look at if you want more out of your ski, IMO.

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1991 550sx, 1993 750sx, 1993 750sx (Wife's ski), 1998STX, 1994 Waveblaster, 1983 550

Big thanks to Newmiller Machine in Oregon for the great work! (Mcn6 on PWCtoday)

"The number of ways of playing footsie with detonation is endless, but nothing works every time. This guarantees that we will never be bored, and will never run out of seized pistons. " - Kevin Cameron

550/440

PS - when I added the OP head, I also switched to a copper head gasket.

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1991 550sx, 1993 750sx, 1993 750sx (Wife's ski), 1998STX, 1994 Waveblaster, 1983 550

Big thanks to Newmiller Machine in Oregon for the great work! (Mcn6 on PWCtoday)

"The number of ways of playing footsie with detonation is endless, but nothing works every time. This guarantees that we will never be bored, and will never run out of seized pistons. " - Kevin Cameron

gemiller

my apologies but yes, i believe its a 15p jetlyne stainless. one of my first mods, just forgot to mention it.

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550/440

You are good with that then, 15 to 15.5 is good on a 550. Keep an eye out for one of the OP swirl cut heads, they are good. Is your 550 an SX or a JS? OP heads are tougher to come by on the SX. Have you got a pisser t'd off of your 1/2 pipe?

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1991 550sx, 1993 750sx, 1993 750sx (Wife's ski), 1998STX, 1994 Waveblaster, 1983 550

Big thanks to Newmiller Machine in Oregon for the great work! (Mcn6 on PWCtoday)

"The number of ways of playing footsie with detonation is endless, but nothing works every time. This guarantees that we will never be bored, and will never run out of seized pistons. " - Kevin Cameron

10mm

Just take your stock head to a reputable shop and have it milled. That will be the cheapest way to get higher compression. Some people just 1211 the head right to the block no gaskets at all. I used to run a w/c head and had good compression (175psi)on my 440. Now I have a milled stock head and 175psi on a 550.Same readings just a cheaper way of getting there. Just remember modding your motor in any way will more than likely shorten it's life. How much could be argued. Reliability comes from your maintenance and ability to recognize when it needs to be done. Just my .02 cents. Good luck with the ski man.

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gemiller

Don't believe so, I have a pisser that's taken off the oem breadbox, and then a hose that runs from the factory manifold to the stinger on the end of the pipe, am I supposed to have 2 pissers? If so i've been running it like I have been for 3 years... :/

It's a 550sx, 1990 piston port with rear exhaust.

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550/440

You can put a pisser in the line on the 1/2 pipe to dry it out a bit. It will add some low end. I had a restrictor in the lower end of the hose, along with the pisser t'd out to the side, it was a nice little mod.

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1991 550sx, 1993 750sx, 1993 750sx (Wife's ski), 1998STX, 1994 Waveblaster, 1983 550

Big thanks to Newmiller Machine in Oregon for the great work! (Mcn6 on PWCtoday)

"The number of ways of playing footsie with detonation is endless, but nothing works every time. This guarantees that we will never be bored, and will never run out of seized pistons. " - Kevin Cameron