Lites class ski setup

[N3vrSat1sfied]

Thread for ski setup discussions:
2016 Rulebook http://www.ijsba.com/wp-content/uploads/2016/02/2016-Rules-Part-3-Ski.pdf

MODS ALLOWED:
Engine: (850cc max)
-Superjet: 760 cylinder allowed with no case modifications, gasket modification,
-SXR:

cooling:

Fuel/Air: A/M flame arrestors, Chokes removed, jetting,

Electrical: A/M CDI's with no additional outputs (example MSD enhancer)

Hull: 4 sponsors, ride plate, intake grate, A/M pole, steering, bars, grips, throttle, padding/mat kits, lifters/wedges

Pump:

MUST HAVE: flexible tow lope, superjet must have visibility spot disabled,

read the thread for farther clarification, please comment with what I need to add to this post.

 

[user_error]

On the 760 top end you just need to go slightly righer, like a 135 main and 70 pilot. Definitely get t handles, they are almost a necessity

 

[N3vrSat1sfied]

On the 760 top end you just need to go slightly righer, like a 135 main and 70 pilot. Definitely get t handles, they are almost a necessity

I cut off those shafts so you can access the screws. I'm already at 132.5 and still a little lean with the 701 top end. Removing the choke plates made a huge diff on those little 38s. Waiting for jetmaniac to get back to me about getting the new top end. So trying to order jets as well


Sent from my iPhone using Tapatalk

 

[Big Kahuna]

760 the way to go unless the rules let you run a B Pipe on a 701, but I think that is only Prowatercross that you can do that.

 

[N3vrSat1sfied]

Got a 760 top end on the way, just need to figure out jetting and get an MSD. Also decided to get an RRP pole. Can't wait get it all together and hit the buoys. I haven't set up in courses in a while due to the cold water, I rode yesterday in a shorty though.

 

[Big Kahuna]

Have you looked at the Aura Poles?

 

[N3vrSat1sfied]

Have you looked at the Aura Poles?

Ya, I have one on my wife's tigercraft. Tony make a great product. Got a deal on the RRP though.

 

[Big Kahuna]

Gotcha. If buying new, Aura....... But a deal is a deal!

 

[user_error]

Be aware that if you have true 62t cases you might need to disassemble them and slightly bore the top case to accept the 760 cylinder sleeves. It can be done relatively easy, just a other step in the process. You can grind them to fit as well but that might raise some eyebrows if you ever get teched. Machining them would look oem

 

[user_error]

Good call on the rrp though. Pick up a steering cable and a straight nozzle as well

 

[N3vrSat1sfied]

Be aware that if you have true 62t cases you might need to disassemble them and slightly bore the top case to accept the 760 cylinder sleeves. It can be done relatively easy, just a other step in the process. You can grind them to fit as well but that might raise some eyebrows if you ever get teched. Machining them would look oem

so the swap is legal, but the grinding isn't?

ive done the steering cable already

 

[Jhucke]

Be aware that if you have true 62t cases you might need to disassemble them and slightly bore the top case to accept the 760 cylinder sleeves. It can be done relatively easy, just a other step in the process. You can grind them to fit as well but that might raise some eyebrows if you ever get teched. Machining them would look oem

As opposed to a 64U case?

 

[user_error]

so the swap is legal, but the grinding isn't?

ive done the steering cable already

It's a grey area. The 760 swap is 100% legal but the rulebook says no grinding on cases cylinder or manifolds. You can make it fit by grinding a little away, but if you are in the top of your field and have to get torn down for tech it might cause some problems. Having it bored on a machine will look oem and no one will be able to tell. You only.need to remove about 1-2mm.


This is for true 62t cases. The 64u cases that are used for the 760 engines(same as 62t except dual pulse line) will fit the cylinder just fine.

 

[Big Kahuna]

Just went and looked at the rules, could not find where it said you could swap to the 760 cylinders. But Displacement is capped at 850cc. Which is stupid for Stock Class.

 

[N3vrSat1sfied]

10.3.5 No internal modifications of any kind, including grinding, surfacing, polishing, machining, shot peening, etc., will be allowed on any engine components.


10.3.12 Cylinders may be interchanged between homologated watercraft of the same manufacturer subject to restrictions announced by the IJSBA. Any modifications to the cylinder or crankcase must be approved, in writing, by the IJSBA. This provision is only applicable to Two Stroke Ski PWC homologated under provision 4.1.2 (550 units).


If the OEM cylinders or the cylinders allowed under 6.3.12 do not provide for a displacement within 10% of the maximum allowable displacement (850cc) then an aftermarket cylinder sleeve may be utilized. The aftermarket sleeve must maintain the same port sizes and specifications as the original OEM cylinder sleeve.

 

[user_error]

You are allowed to. It's the part that says "if oem cylinders do not allow for total displacement to be within 10% of class maximum (850cc) then replacement oem sleeves may be used". Cylinders are both oem the sleeves are different sizes. Every competitive sj on the line at havasu has 760 cylinders bored a few mm. It's been like that for several years now in lites class


Edit: he mentioned it above. You can swap cylinders to get the displacement where it needs to be (within 10% of max)

 

[Big Kahuna]

I read the "No Grinding" to be referring to porting of the cases......... Clearancing would not fall in same catagory

 

[user_error]

That's why I mentioned machining them to look oem as opposed to grinding. Grinding marks on a lites ski will obviously raise an eyebrow in tech but if you take 1-2mm off on a mill just to fit te sleeve you will never be able to tell. It will look just like oem. This is how people do it and have passed tech

Just a dumb shortcoming in the rulebook imo

 

[Big Kahuna]

Still trying to figure out how your gonna get a 760 to 850cc!!!!!!!!

 

[user_error]

You dont need or want the 760 to reach 850cc, the exhaust restricts it too much at that size anyways. We're just looking to get within the 10% of the 850 allowable.

You can get it there by boring out the 760. You can go up to 785cc or so on a 760 cylinder iirc. When set up right that will get you quicker holeshots and comparable top speeds to and 850cc sxr.

10% of 850cc is 85cc.
850cc-85cc=765cc

Or 850cc x .9 = same result