Custom/Hybrid Perfect racing driveline

[Vumad]

I know this is a freeride forum. I know it's a goofy question.. blah blah..

What would be the best driveline of the available options for a racing set up. If you had a stand up hull built to race, which would would give the best performance. Talking about the modified 760 yamaha motor, 800 SXR motor, or a stock/lightly mod kawi 1100 or yamaha 1100/1200.

Would the 155mm Yamaha pump be best (like WB2)? Or would that large pump give minimal gains on the bottom and scrub the top a bunch?
Would the 144mm Yamaha (SJ) or the 140kawi (SXR) be better for a good hit with more on the top? Which would be better? Why?
Is there a 4th option?

I'm talking stock options, because I believe I would be told a 148mm mag pump would be best. Excluding Seadoo, afraid of those guys.

What about setback? Say you're modding an existing hull to take w/e you want it to take. Stock pump placement good? Run a 07 SJ drive shaft or 08 drive shaft with setback pump? etc etc.

Thanks for opinions.

Just because someone will ask, I'm creating the discussion for 2 reasons. One, I'm curious because I've been reading about pumps and drivelines, and previously I had assumed the 155 would be best, but I am now believing the contrary. Secondly, and I know you guys will think I'm goofy, but I'd like to put this GP1200 motor I have sitting on my shelf in my X2. I wont be doing it anytime soon, but I have everything almost from a junk donor ski to do the mock up, so I can tinker with it a little here and there. The GP1200 pump tunnel is stupid in it's design (god aweful amounts of metal there). I think a WB2 or SJ tunnel would be best. However, I could also run a SXR pump and the correct couplers.

Also, keep in mind the availability of aftermarket pumps. If the 140 kawi and 144 yamaha are negligable in difference, but the kawi has a better upgrade option, then that is a perk with considering. I can't afford a mag pump now, but if I were able to build a nice ski, I would be upgrading it later.

I'm parting my X2 and putting the money into my superjet, so I wont be building anything quite yet, but I have gathered a number of free junker parts to do a mock up. My plan was to set everything up because I can build the hull for very little, and then buy a doner GP1200 when the time comes.

 

[waxhead]

The 3 cylinders are better for the reason that you can get the same power as the twins and still retain some reliability. The extra weight also helps with handling on a race boat as well

 

[scottie mac]

IMO, if you are talking racing, the sxr pump tunnel design is best. It is designed to stuff the pump. Also, the Kawi drive live is much more user friendly since the shaft is free floating, much less likely to strip splines, etc.

As for pumps, the new Kawi 145mm mag with the larger 83mm hub is awesome. We use that in our full race fuel sxr1100s with great success.

If you would prefer to go with a Yamaha driveline, the set back 144 skat with new 83mm hub is great, but like the Kawi version, really expensive. Bang for the buck, you can't beat the solas 144s. I run one of them in my kawi1100 B1 and it works great. Would the skat be better? Probably, but I'm not willing to spend 1400 bucks MORE to find out, lol.

Scottie

 

[Turbosauce74]

I believe in skat pumps to the very end, and worth every penny. Stock kawi sxr pumps can't handle an 1100 properly and just won't hook up. If you're rec riding that's a different story, but if you plan on racing go skat.

 

[Vumad]

2 of your mentioned Skat pumps. I think scottie mac was pretty clear. Turbosauce less so.

I know an aftermarket pump would out perform a stocker. However, I would only be dealing with stock for now. However, upgradeability is important.

Would it be better to design the system around the Yamaha pump or the Kawi pump? Lets say stock pump A is better, but upgraded pump B is better, I'd rather have lesser performance from stock B because it would be better upgraded. That make sense?

Price is a factor too. However, they kind of work out the same. The Kawi pump is expensive to replace the liner. However, the yamaha bearing housing is very expensive. Neither is really better.

I would only be setting the motor back about 2 inches, so I'd need a drive shaft to accomidate. I could run the Kawi pump with a X2 drive shaft and set the pump, bulk head and motor all back 2 inches. Otherwise I'd have to have a driveshaft custom made which wont be happening.

Thanks for the opinions so far.

 

[Turbosauce74]

Skat can always do custom length driveshafts.

 

[scottie mac]

The Skat Kawi pumps over 140 are all aftermarket, they don't use the original housing and sleeve it. So, the entire pump is stainless outside and lined. Plus, the Kawi pump is a one piece pump, meaning you don't have a wear ring that is separate. The 145mm Kawi mags are being used in 200 plus hp race skis, so you will be fine with it. Plus, if you can graft in an SXR intake, you will vastly improve the entire driveline for the X2. If you do go this route, you can go to Atlanticjetsports.com and look at all the kawi driveshaft lengths. There is a good chance you can find one to work without having to buy a skat hand made one. While the skats are nice, they are just like their pumps - expensive.

Either way, you can't really go wrong. Any of the larger pumps are going to be a vast improvement to the stock X2 pump, no matter if you are talking skat, solas, set back or standard.

Scottie

 

[kevbo]

A 140mm pump needs more rpm and is more limited on capacity than one of larger diameter. Basically you need over 7500 for 140mm. A larger, slower turning engine needs a larger pump. The inlet is important, racers need long shallow inlets, freestyle needs shorter and wider ones.

 

[Vumad]

A 140mm pump needs more rpm and is more limited on capacity than one of larger diameter. Basically you need over 7500 for 140mm. A larger, slower turning engine needs a larger pump. The inlet is important, racers need long shallow inlets, freestyle needs shorter and wider ones.

So superjet based pump intake or SXR pump intake would be better for my dreams of a 1200 race boat?