Not sure what I have here. 2003 SJ 760 or 701?

[Kraig]

Can someone help me figure out what I have here. I got a 2003 SJ, I was told it had a 760. Having the ski for a year now I wanted to make some mods to it. I wanted to order a B pipe for it with the 62T manifold. So I have been reading up on what to get for my new jets in the carbs. I went out to my ski today and I noticed that the head says 64U. I purchased a milled head that has 64x. so now I am wondering if I even have a 760 out of a Blaster 2. Using the search function I find that a 64U is a 701 from a sit down. So now I am starting to wonder what I have. I see the crank case has 62T at the front of the motor. I don't see a stamp on the middle section so I'm not sure what size it is. The exhaust looks like it is from a normal SJ. The carbs are black, Should I measure those to see how big they are if they are truly a 44 or a 38? There is a sticker from Yamaha that says 64V. I don’t know what that even means.

How should I determine what engine I have. Would I have to pull the head and measure the sleeves to see what I have. I am not sure if the guy lied to me and told me I had a 760 when really it was a 701. I am just trying to figure out what I should all order for bolt on’s and how to tune this thing on pump gas. It has good top end, more then my buddy's 2016 stock SJ, His has more low end POP. reading up that always sounded like a 760.

Also my stock Bilge is not working. There was a stick shoved in there that I was able to blow out but am not sure if I am missing anything at the pump end. My Kawaie 650 has a metal pipe sticking out to make the stock bilge work. dose this phot look right? I always have a good amount of water in there that is not warm and my ski seams to take on water if we sit at an island for a while. I have a bilge pump but it would be nice to have a dry ski at the end of the day when I pull it to put away.

 

[Big Kahuna]

Does the motor have 2 OEM pulse fittings or 1. OEM 760 shortblock will have 2.
Or you could have a 760 cylinder on there. Hard to go by head. Post pics of cylinder and exhaust.

 

[Kraig]

How do I tell if it’s a 760 cylinder? I only see one pulse feeling

Not the best photos but here’s what I got. Let me know if you need something else.

The exhaust manifold has 61x on it.

 

[Kraig]

It looks like there is a stamped circle that says 2Q4 on the cylinder

 

[Kraig]

This sticker say 64V J700k 71.

So it’s a 701 case but I knew that due to the stamped 62t

 

[surfjunkie]

i think the three bolts on the carb plate indicate 38's which would point to a 701

 

[surfjunkie]

44's have 4 bolts i think

 

[surfjunkie]

that barb for the bilge siphon looks right. see if the plastic box is sitting flush against the bottom.

 

[surfjunkie]

also the 62t/62t 701s out of couches have porting (or port timing) that favors top end .....

sorry should have put this all in one post lol

 

[Kraig]

Ok

So my exhaust manifold has 61x on it and 6m6-0
3 bolt carbs and my cylinder had Y-3 on it.

Looks like a 701.

I think I have to pull the head and exhaust manifold and confirm with a micrometer before I order a Bpipe.

So with this set up am I ok to run a higher compression on pump gas? Something like 37cc domes at 170 psi or do I need to worry about port timing still?

The plastic box for the siphon is flat on the hull it’s not sucking up water though.

 

[Storbeck]

That's a 701 case, those are 38mm carbs, and that's a 701 head. It's still possible somebody put a 760 cylinder on it, that's not an uncommon thing due to some goofy racing rules. The cylinder can be most easily identified by two extra gussets where the cylinder bolts to the case on the intake side, here. I don't see it so I don't think it's a 64x 760 cylinder. The 701 62t cylinders don't have those (or at least the two cylinders I have don't have them), so that doesn't 100% confirm it's a stock cylinder.



There is a machined surface with a tapped hole on the left rear corner that prevents the girdle bolts on a girdled head from fitting unless it is machined off, should be easily visible, but none of your pictures is at an angle that would see it. If it doesn't have that it's a 61x stock superjet cylinder.



Also the cylinder would have 62t cast into it and 64x on the printed tag if it's a 760 but that's going to be hard to see while it's installed in the ski.

Also of course it's possible that somebody bored the stock cylinder which you wouldn't be able to tell without pulling the head off.

 

[TheBuzzard]

the 64v cases came with a 701 top end but those cases are the only 701 cases that a 760 cylinder drops right on. those are the same cases they use on 760s and they do only have one pulse fitting since they come with 38s. they do have the blank boss on the other side that can and does get drilled out for the second pulse fitting for the 760 that comes with 44s. between the cylinders, behind the carbs, it'll be cast 61x if its a true SJ701 cylinder. if its cast 62T then it could be a couch 701 or 760 cyl. a 701 cyl can be punched out to 84mm which would give it the same bore as a 760. if its a 62T cyl, it will have an extra web between the cylinders where an exhaust bracket bolts to hold the huge heavy pipe that comes on couches. that web needs to and does get ground out when you put a girdled head on there.

 

[Kraig]

Ok so I pulled the head.

It’s 81mm. Thouse 100% 701.

So I can run 37cc domes on pump gas then right? And I can just go ahead and tune this thing like a normal 701 or do I have to be concerned about anything else since this came out of a couch?

Here are some photos of the Pistons snd cylinders and cylinders after I pulled the head and the inside of the current cylinder head.

Do they look OK?

 

[TheBuzzard]

it didn't come out of a couch. that's a 61x cylinder

 

[Kraig]

Dose it look like my front cylinder is too rich?

Or is my rear to lean?

Just wondering with the different carbon build up.

Thanks for all your guys help I have learned a lot!