300/440/550 650SX pipe and modification questions

[ATS_Aaron]

I'm normally a Superjet guy, but I bought a 1989 650SX as a spare for friends and beginners. I haven't ridden this one yet, but it is actually my second 650SX, so I know how stock ones ride.

On a Superjet a pipes helps....A BUNCH. Do 650SX's see similar gains? What brand should I look for? Like I said it's a spare ski, so I'll probably be searching the classifieds and Ebay for one.

What other mods should I do? I think it has the tiny 28mm (is that right?) carburetor, so I assume I should look for a 38 (?) off a newer 650SX, or maybe just an intake manifold becuase I think I have a spare 44mm carburetor off a Polaris 785 Pro.

What compression should I run? Have the stock head milled, or should I look for an aftermarket head on Ebay?

Thanks,

Aaron

 

[john zigler]

hi aaron.

yes, the 650 kawi motor responds well to bolt on's. ( pipe, compresion, bigger carb ect).

if you want the best / most hp. loof for a factory pipe, or coffmans. change the carb to a 44SBN, good flame arrestor, aftermarket, or cut your head.

i have new, intake manifold here in stock for 44mm carbs for the 650. 100.00.i also have new jetlyne fiberglass racing reeds. 30.00 /set
i have new jetlyne scoop grates, 10.00
one used, but good mariner ride plate with fins 50.00
aftermarket water box, looks like new. 50.00
handle bars, grips, throttles, ect.

if you want to go the cheap route. i have a PJS 650 pipe "stinger cone" 50.00
this takes the place of your stock cone, and works on your stock pipe. it is different dimensions, and will make a noticable difference. ( with some water routing changes too).

back in the day, i had a buddy with an 87 650SX. he had the exh cone, a 44mm round body carb, shaved head, and a waterbox. that ski flew!!.

on your head. typically on the kawi heads, there is enough squish room to mill off .015 to .020 and still run on pump gas. this should put you at about 175psi, at .050 squish or so. check you squish, and compresion first though. usually .010 milled off is close to 10lbs on the guage.

we could probably do a "package deal" on some of these, and the parts we talked about a week ago or so.

let me know if i can help in any way.

zig

 

[extreemthrottle]

yeah, what john said, on my old 650, i put a factory pipe on it (off of a 750sx) it had a westcoast on it beore but could'nt come close to the power the factory pipe made. single 44 mikuni is also a great setup. i had the exhaust ported slightly and that also helped. i had compression of 165 withthe stock head and it did a true 48 mph on the gun! but not near as impressive as the low end it had. i miss my old snot rocket..... check out the thread on it and see the setup..http://www.x-h2o.com/threads/6683

 

[ATS_Aaron]

I posted a turf question in your thread the other day. When you hydro-turfed the sides and top of the tray did you remove the original vinyl pads or did you glue the turf to them?

John - I'll let you know what parts I'd like.

Aaron

 

[Talsivar]

hey john is this the pjs pipe you are talking about? it came on a 650sx i picked up it has the stock headpipe and manifold.

 

[john zigler]

talsivar......

no, that looks like an aftermarket pipe, mated to the stock head pipe.

i know some of the very early model pipes had stailess head pipes, and they were known for cracking, and leaking. i bet someone just replaced it with the OE one.

the one i have here, ( I need to get a pic) is just the rear 1/2 of the OE pipe. the stock 650 pipe has a coupler, with band clamps in the middle of the cone. this is just the 2nd 1/2 of the cone. it has different dimesions than the stock one, to tune your stock pipe. i may be wrong, but if i remember correctly, this what was done early on. there was no " full pipes" right away for the 650. the stock 650 pipe, is really not a bad design, IMO the only major improvement wasn't until factory, and coffmans made there full pipe.

don't get me wrong, the westcoast, mariner, kerker, PJS, ect later all had full pipes, and did improve over stock, just not like the factory, and coffmans.

somewhere posted on here, years ago there was some great tips on modifying a stock 650 pipe. and it was true, you could take a stocker, make some water routing mods, run this tail cone, and it made a good difference, for less $$$$. i would say HP gains are equal to any of the PJS, mariner, coffmans, ect pipes. if you look at their demensions, they are really not all that different than the stock pipe. ( as you can see by the OE head pipe, and manifold working with the pipe chamber). it was just changes in the stinger cone, and internal water routing, to make HP at different RPM's.


zig

 

[cookerq62]

I had a 650sx with a single 44sbn head and factory pipe. I ran the stock pipe as well and there wasn't much diff. The Stock pipe is one of the better oem ones. The factory pipe chamber for the 650 is kinda small compared to the sj and 750 pipes which you could prob squeeze in the hull. The most gain I got was from the single 44 and messing with the water routing in the pipe.

 

[ATS_Aaron]

Thanks. I'm gonna try and make some changes tomorrow and get to the lake on Tuesday.

Aaron

 

[spork]

i just put a 38mm carb and manifold in place of my 28 on my 89 650sx and it made a big difference

 

[randalj1]

i just put a 38mm carb and manifold in place of my 28 on my 89 650sx and it made a big difference

Me too!

 

[subseawellhead]

i just put a 38mm carb and manifold in place of my 28 on my 89 650sx and it made a big difference

Thats what i'm lookin for, I picked up a Skat blue pump (ex Jeff Pruier) and lighthtened driveshaft for this machine also.

 

[yama_freak615]

i have a mariner head pipe and midpipe for sale, you know which thread

 

[subseawellhead]

You bet, problem is, now collecting parts to mod the square, bought a Protec 61x ported cylinder from Wax today. So many projects, so little time.

 

[SeaLion]

The stock exhaust can be modified on the 650s. You need to remove the headpipe. Look inside and you will see a hole for water injection. You need to fill that hole with JB Weld and dril a new hole with a 1/8" drill bit. This new hole will run the exhaust drier and raise rpm.

The tailcone zig is referring to was actually made by Kerker. There might have been a PJS comparable one? Anyway, they came with a nice plug for the headpipe hole I was referring to earlier and it had a smaller (1/8" hole in the plug) hole. You had to install this restrictor inside the headpipe when running the new cone to make the extra power. I ran that set up on a 87 650SX back in the day and it did work well for the $45 cost. You can really accomplish the same thing by the JB Weld and drill method. The next tip is to get an exhaust manifold off of a 650TS. They were like a performance manifold and different than the 650SX and X-2 manifolds, although later model SX and X-2 might have had the updated ex. manifolds?

 

[sjaholic]

modified 650 pipe in my first 550/650. along with what sealion said you will need to drill, tap and add a fitting to the headpipe. the location for this is toward the back of the headpipe on the raised flat spot.

you will need to add a fitting to the end of your stinger. connect the two with hose.

 

[dbrutherford]

Do exactly as SEALION said!


I did the same Kerker tail cone and restricter mod to my old stock X2 and it ran just as good, I mean better than my friend's 650 SX with a West Coast pipe.

Also ditch the 28 mm carb and go for the 38 mm or better yet a Kehin 42 or a Mikuni SBN 44 mm carb. I have a nice SBN 44 manifold on eBay now:

http://cgi.ebay.com/ebaymotors/ws/e...RK:MESE:IT&viewitem=&item=260046837318&rd=1,1


It needs some studs but they can be had from Hot Products or any ACE Hardware.



I always wanted to take a 650 stock pipe and mod one.... I would weld the two sections together. Then I would weld up the hole in the head pipe so I could redrill/mill a hole in it for a FPP water screw. I recomend you drill out the factory bypass fitting and put a larger 1/8" NPT fitting in its place, I did do this one once.

DAVE



PS could you put up some more pics the 650/550 engione swap? I mainly want to see the mods done to that pipe.

 

[FL-cracker]

Has anyone bored the stock exhaust manifold? If so how big? My friend has a 650, I will try the pipe mod you guys speek of....he realy needs to shiet can that 28mm carb as well.

 

[dbrutherford]

I never have but I will say that you do need the "TS" style manifold. My 93 X2, 95 X2, and 91 650 SX all had them. My friend's 88 650 SX didn't. There was no exhaust diverter period in there. Of course the stock TS style doesn't really have that steep of a diverter either. My Coffman manifold had a decent one but really the steepest/biggest I ever saw was a Jet Sports.


I have a 38 mm carb set up for sale but I already promised it away to another guy on here. If he doesn't want it, your friend is more than welcome to throw up an offer.



I am not sure if I agree with the fitting added to the back of the head pipe. I always wanted to add a FPP water adjustment screw there.

Still though do like they did and put a bigger fitting where the stock original bypass is. Also do the JB weld to the hole in the back of the head pipe and re drill it.

My concern is that if you eliminate too much water, the pipe will run hot and them melt couplers and the gas tank. Plus it will raise the under the hood temps to where the air in the engine compartment will be way too hot.


DBR