Big pin, little pin 750 sxi questions

[ski_crazy]

What is the facts about "big pin" and "little pin" motors? I have a 96' 750 sxi. How do I tell the difference in the two and find out which one I have. I'm clueless about this subject. Thanks for any help.

[crab]

small pin 10 intake bolts, 12 on big pin.

[ski_crazy]

Thanks crab.

What does the "pin" refer to?

[john zigler]

"big pin" is in reference to the size of the crank pins.

they really are two completely different motors though. port timming is different between the two, cases, cyls, pistons, head, ect, are all different.

your 96 SXI should have the "big pin" motor, unless some one switched it.

all "small pin" motors were single carb motors, and crab is correct, only had 10 intake mount bolts.

hope this helps.

zig

[ski_crazy]

Mine only has 10 bolts on the intake manifold. It is a dual carb with R&D intake though.

[crab]

Small pins have the best freeride porting.

[djkorn1]

Someone changed it to duallys. It is a small pin...

[ski_crazy]

Is one better than the other? Is there anything I should change? The motor is pulled and sitting on my work bench. Now would be a good time to change anything that needs it. Specs are, Ocean Pro f/a's, R&D intake, R&D head, Factory Pipe exhaust manifold and full Factory Pipe.

Also I pulled the spark plugs after a four hour ride, they were brand new, and the back cylinder plug was covered in what looked like car motor oil and the front plug was spotless. Why? Is there something wrong? the ski ran flawless and had no problems.

[crab]

Not that simple, the small pin and big pin cases are different, the cylinders are different also. You can put a small pin cylinder on a big pin case, but not reccomended by group K, and vice versa. They made like 5 different 750 heads, with different CC's depending on model and year. The small and big cranks use different pistons, due to the pin size. The PTO thread size is different on the 2 cranks as well. I use 650 electrics on mine as its simpler and mostly reliable, the 750 electrics seem to go wacky for no reason, but there are A/M ignitions that will work with them including enhancers or Advent. When they came out with the SXR, they kept the big pin design, added more CC, but lowered port timings that the SXIpro had and beefed up the cases, however I still like my small pin for the great bottom end and under 7000 rpm.

[Scorn800]

Big pin is 22mm wrist pins- small is 20mm
all 750 flywheels are the same except i believe 92sx. I was told different taper.
750 electric's are better. Digital CDI & on 04 sxr's DC CDI
750 stator's are know to go bad

[john zigler]

Big pin is 22mm wrist pins- small is 20mm
all 750 flywheels are the same except i believe 92sx. I was told different taper.
750 electric's are better. Digital CDI & on 04 sxr's DC CDI
750 stator's are know to go bad

the way i remember it, the small pin, and big pin cranks had different tapers on the flywheel end.

electrics are different between the two motors as well. stator coil assy timing is different to match the different motors. CDI's have different timming curves, and rev limits to match different motors.

the early 750 stator's had week grounds, and are known for going bad.

crab said it pretty good. don't forget the 750 small pin piston's have a posrtion of the piston skirt cut higher, and the big pin pistons do not have this.

also, ( again the way i remember it) the later small pin motors, have the same larger PTO threads, so you cannot go by this alone.

i have heard of guys running the big pin lower with a small pin cyl, and i though it was supposed to work well. ( again going by memory). i have a friend who is redoing his big pin 750 X-2 as we speak, and i know he is going to build his motor like this, so i guess we'll see. basically he is going to cut his piston's like the small pin ones, and run a small pin cyl.


ski crazy;
what color is your motor? a 96 750 should be green. if yours is silver, someone may have changed your motor. you have an aftermarket intake and lots of other bolt ons. like i said earlier, a big pin motor has 12 intake stud holes.

the debate between the two motors has gone on for a long time.

basically, the "big pin" has a "stronger" bottom end, and crank. it has taller port timming, which leads to making more hp in the upper RPM's. these were kind a "turd" on the low end, but pulled hard up high. good for racing, poor for freestyle.

the "small pin" motors have lower port timming, and make MUCH more power on the bottom end. but, they have a weaker crank, and bottom end. ( not that this can't be fixed up). these make much better free style motors, and generally are funner to ride.

zig

[john zigler]

why cant kawi just be like yami?!?!?!



charlie, i honestly laughed out loud when i read this. i have worked on may yamaha's over the years, but i have NOT had the chance to do alot of interchangeing of parts, ski's, motors, ect. everything i have done here in the shop is simply replace, rebuild, repair, ect, so i do NOT claim to be a yami expert by any means.

personally, i consider myself a kawi guy, just because that's what i have always had. back in the day, when we started jetskiing, that's all there was. i have always just stayed with kawis. i started with an 82 550, went to an 89 550, then put a 750 motor in it, then went to a 750SX, then a SXi pro, and now SXR's. (not that i don't like the SJ's, infact, i think i want a round nose).

anyway, long story short, i think that same thing whenever we are messing with yamaha parts, 61X, 62T, 62T cases, with 61X cyls, ect. man, just the different mid shaft bearing assemblies alone confuse me. so to me, i always think, "why can't yamaha be more like kawi?"

now after all this typing / reading about the kawi's, i could see how someone could be confused. i just guess i never think about it, and it is more of what you know, and are comfortable with.


zig.

[djkorn1]

Zig, you took the words out of my mouth with the Kawi/Yam thing.

At least Kawi motors have been updated after 1996. Thats why a stock SXR blows a stock SJ out of the water.

*Flywheels: Different taper for big/small pin (not interchangable)
*Cases: Big pin can be used on small pin, but not the other way around unless you grind the hell out of em.
*Cyllinders are interchangeable, but have different porting
*Heads are interchangable but all have different cc's, so different psi.
*Pistons are not interchangeable due to pin size.

BTW:

Small pin 750 motors: Better low end hit
Big pin 750 motors: Tough to get low end out of them
Big pin SXR motors: Hit WAYYY harder on top and bottom. (must be the porting and extra cc. Maybe diff electronics too.

[Scorn800]

The 750 flywheel's are all the same from 93 & up. I know I've tried them.
All 750 stator's will work with 03 and under cdi's. I know I've tried them.

[dbrutherford]

A few things i can add.

I once had a 92 750 SS engine I put in a 650SX. Well the 92 750's had a "bastardized" crank as RAD told me. Supposedly they used 650 rods that a different size pin size. Can't fully remember the details but just that they couldn't rebuilt them because there weren't rods available.

Another note about the early snall pin 750's were that they had the through the cases hole for 650 style stator wires. They just used a little plug that was screwed in place. On later big pin engines this was never machined. So to run 650 electrics, you have to drill the center hole out, then also drill/tap the two screw holes. All 650 cases had this done from the factory.

I think I am going to buy a set of 800 SXR cases & cylinder from Kawie. If I can get them at the dealer's cost then I will be making out. Then just buy a Hot Rods crank, Pro-X pistons, ADA head, R&D intake... ect and build up the engine. Otherwise I plan to buy an 800 SXR just to pull the engine, pump and electrics out of it. I just can't seem to find a decent 750 engine that won't need a bunch of $$ to fix. Plus crank rebuilds are expensive and you can't buy a new small pin crank.

[crab]

If I do another, I may go 800 and drop the cylinder right down on the cases like my current motor, no base gasket only 1211.

[Scorn800]

If I do another, I may go 800 and drop the cylinder right down on the cases like my current motor, no base gasket only 1211.

Hey that's a stock class secret. shh. shh, shh:sneaky:

[Scorn800]

I'm with dbuherford
I've been told 92 750 cranks were odd balls. I was told it has the same flywheel taper as a 650 crank. I've never owned 1 so I don't know for sure.

[Big Kahuna]

Hey that's a stock class secret. shh. shh, shh:sneaky:

That is something that Bill Haig is always saying........ If it is perfectly flat you dont need a gasket!!!!!!!!!!!!!

[djkorn1]

I did too. A 94 flywheel did NOT fit on my 98. The crank is different and has a different taper.

The 750 flywheel's are all the same from 93 & up. I know I've tried them.
All 750 stator's will work with 03 and under cdi's. I know I've tried them.

[crab]

I must have the early crank, the PTO and flywheel fit off my 650.

[ski_crazy]

Thanks for the help, I think or the confusion I'm still not sure:veryhappy:

Zig my motor is teal green. It does have 12 bolt holes but only 10 have studs with nuts. The other two holes are on the side of the intake hanging off the side with nothing to bolt to.

[WFO Speedracer]

I am pretty dang sure all green engines are big pin.:biggthumpup:

[john zigler]

I am pretty dang sure all green engines are big pin.:biggthumpup:


yup. sounds like someone just removed some of your studs. if it is the light, teal green, it is a 96-newer motor, and will be a big pin.

[djkorn1]

Yep...big pin. Somebody took the studs out to mount the old school Intake. :sad6:

Thanks for the help, I think or the confusion I'm still not sure:veryhappy:

Zig my motor is teal green. It does have 12 bolt holes but only 10 have studs with nuts. The other two holes are on the side of the intake hanging off the side with nothing to bolt to.

[ski_crazy]

Here is a couple pics of the intake and the open holes. What gives?

4012840129

[john zigler]

i have no idea what the heck kind of intake that is. i have never seen one hang over the side of the block like that. lokks like it was ment for some kind of extra mount bracket for something.

[crab]

Not a Kawi manifold?

[ski_crazy]

Its an R&D manifold. It works and its pretty being polished. That polished has to add at least 3-5 hp, huh.

[ADDict]

How can I tell which engine I have? It's a silver case small pin engine with the 10 hole intake pattern. And it needs a lot more work than I thought, but thats another story.

[crab]

How can I tell which engine I have? It's a silver case small pin engine with the 10 hole intake pattern. And it needs a lot more work than I thought, but thats another story.
Explain?

[tmetz]

thanks for clarifying the differenced in pin motor's. I have two of them sitting on my uncles garage floor. And i was so confused trying to figure out big pin or small pin... I think i have it under control now... lol

[dbrutherford]

those 2 holes could be for external fuel pump mounting..... if youre in to that sort of thing.

I used ot have an R&D intake manifold just like that. The extra bolt holes are exactly what Charlie said they are for.

The newer 800 SXR R&D intake manifolds have a plate that bolts down to the carbs. Then this plate and carbs bolt down to the intake manifold. I believe they sell one just like this for Yamahas too. This way there is an o-ring between the plate and manifold. You seal the plate to the carbs with a couple of Mikuni SBN 44 green gaskets. This lets you remove the carbs for jetting changes without the having to reuse or replace the green gaskets.

You have a big pin engine. To use that intake manifold, they removed the two inner studs. If you compare cases for big and small pin, there is not even a place in th casting where the two inner studs would be, on a small pin case. Big pin is only the set of cases that have them.

When I built my 92 750 SS engine and had the "unrebuildable" crank due to the crazy rod size, I just bought a new 94 750 SS crank from my dealer. I used a 650 style flywheel on it no problems. I have a spare 750 flywheel I believe came off a big pin crank and a spare 650 flywheel, I will have to compare the two.

[ski_crazy]

Thanks for all the insight guys.

[Waternut]

If you compare cases for big and small pin, there is not even a place in th casting where the two inner studs would be, on a small pin case. Big pin is only the set of cases that have them.

Is this definate? I always thought I had a small pin in my 92 but mine has the inner holes for the intake manifold. I don't use them but the casing certainly has the holes.

[dbrutherford]

I would have to dig up some pictures of my old 750 engine, it was a small pin for sure since it came from a 92 750 SS. I am pretty certain that there isn't even any material on the small pin cases for the two inner holes.

Liek i said before the big pins have these two holes even if they are not using them. Some manifolds as mentioned before will not use these two studs and they have to be removed for the manifold to fit.

That is why this is the definitive answer if a set of cases are big pin or small pin.

[john zigler]

Is this definate? I always thought I had a small pin in my 92 but mine has the inner holes for the intake manifold. I don't use them but the casing certainly has the holes.


this really can be hard.....

all big pin motors have 12 bolt intakes. not all small pind have 10 though..
only the single carb motors have the 10 bolt cases.

for instance, the 93 SSXi was a small pin 750 dual carb motor, and that has 12 intake bolts.

then how about the 95 750SXi? i always thought that was a big ppin motor, but after looking up crank shafts, i now think it is a small pin. this too has dual carbs, and a 12 bolt intake. thus 96 was the 1st big pin.


zig

[tor*p*do]

Kawasaki 750 standup History

1992 750sx 20 mm rods Keihin (1) 140 mm pump
1993 750sx 20 mm rods Keihin (1) 140 mm pump
1994 750sx 20 mm rods Keihin (1) 140 mm pump
1995 750sxi 22 mm rods grey Keihin (2) 140 mm pump
1996 750sxi 22 mm rods purple Mikuni (2) 140 mm pump
1998 750sxi pro, new hull Mikuni (2) 140 mm pump
1999 Mikuni (2) 140 mm pump
2000 Mikuni (2) 140 mm pump
2001 Mikuni (2) 140 mm pump
2002 Mikuni (2) 140 mm pump
2003 SXR 800 Mikuni (2) 140 mm pump
2004 Mikuni (2) 140 mm pump
2005 Mikuni (2) 140 mm pump
2006 Mikuni (2) 140 mm pump

[tor*p*do]

or so I have concluded . . . .

[john zigler]

stiil though, what about the early 93, 94 SS XI sit down motors? these could feasably end up in a stand up. the 93 was a dual carb, with 12 bolt intake, and from what i can tell by crank part number is a small pin.

[tor*p*do]

when you are talking about 10 - 12 year old boats,
sometimes what is in there is a mix of 750 parts from different years:scratchchin:

those old couch motors work fine in 750 standups
just like pulling a 701 from a VRX Pro for you SJ!

[john zigler]

when you are talking about 10 - 12 year old boats,
sometimes what is in there is a mix of 750 parts from different years:scratchchin:

those old couch motors work fine in 750 standups
just like pulling a 701 from a VRX Pro for you SJ!



yes, i know that.

i don't think you get what i am saying.

starting in 1993, kawasaki offered a dual carb 750 motor in the SSXi 2-seater couch. this was a "small pin" 750 mtor, with dual carbs, AND a 12 bolt intake mount.

SO, like you said yourself, over 15 years time, it's hard to say how many motors have been switched around.

i am just answering jfw's question of "is this definate?" and IMO NO! it is not.

zig

[dbrutherford]

Here is a good example of the two:

Big Pin:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120197481689&ssPageName=ADME:B:WNASIF:MOTORS:1123

Small Pin:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120197481770&ssPageName=ADME:B:WNASIF:MOTORS:1123

Notice how there is no place for the extra two inner studs.

DBR

[Coreyf983]

forgive me if I missed it then, but if I have both 750sx electrics, and 750sxipro electrics, which is the better to use for a small pin engine?
edit: and by "better" I mean what are the pros/cons of each.

[crab]

forgive me if I missed it then, but if I have both 750sx electrics, and 750sxipro electrics, which is the better to use for a small pin engine?
edit: and by "better" I mean what are the pros/cons of each.
650 electrics, simple but some machining may be required, coils getting a little more scarce. Only 2 options in spark curve with charging systems, stock and Dales without any retard.

750, digital with lots of a/m options for curves etc., however stators seem to be the weak link and they run heavy stock flywheels. More flexability.

[Coreyf983]

so are the sx and sxi pro elecs the same?

[john zigler]

so are the sx and sxi pro elecs the same?


no. the 96-up SXI CDI has a higher rev limit, and CDI has a more aggressive timming curve. same with the stator, timming is different.

big pin electrics work well on a small pin.

zig

[Coreyf983]

what does it take to drop down 800 cylinders onto a big pin crank?

[scott07]

Ive seen a few places that say the stator timming is different between big and small pins..... but isnt the timming built into the cover that everything mounts to? The trigger and stator are both mounted to the cover which would determine the timming correct? This is what timming advance kits do.... it simply moves the mounting position on the trigger a few degrees
If im wrong are you all saying a small pin stator wont work on a big pin at all? or just not as well?

Also do all big pins have the same port timming or did sxi pro cylinders have lower port timing?

[dirtnut99]

I have the ss xi motor in my 93 sx. Its grey with kawi green head, dual carb, 10 bolt intake; therefore Small Pin...