Seadoo X4 1100 conversion build/resto

[Alter Ego Trip]

Well I figure I'd start an actual build thread so I could pool all questions and answers into one thread. I have a really hectic schedule so bear with me. I will be doing a restoration and swap at the same time.
My finalization date is May 31st. No rest for the wicked.

Ski 1995 Seadoo XP

Body modifications:

SPI hood
Jet trim seat
Beach House sponsons
Hydro Turf traction mats

Engine Modifications

Engine rebuild being handled by Fullbore
6 degree timing advance
Fuel baffle from 99 SPX (5/16") to supply fuel
Big hub pump from a Seadoo RFI pitched to 16/23 by Glenn
R&D 85/88 Nozzle set (for now until testing complete)
Kommander head kit
Reed spacer and V Force 3 reeds
Driveshaft being built by local machine shop
Raddudes conversion plate
Dry pipe mod
Tau Ceti FA
Upgraded coil wires
Modified water box


Current questions

Head: How necessary is a girdled head? I will be running 150 psi for use with 91 Octane

Ignition Advance: There is of course the mod for the 3 degree. Is 6 degree too much for 91 Ethenol free fuel?

Rhaas makes an adaptor plate for GP1200 carbs. With exception of hogging out the stock intake to match, are there any other surprises that I need to be aware of if I bolt these up? Do these require the use of an aftermarket fuel pump like the DF62?

Props

Shout out to Scottie and JDAKRT who have made this build possible due to a wealth of information.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

Spent the day removing all the baked on stickers. I hate this part. Also peeled off the traction mats which will be replaced with Hydo Turf. Motor is unbolted, I just need to get my new hoist mounted back to my ceiling. I'm over pulling motors by hand lol.



Also working on pulling the 787 with everything out of my SPX to put in this mint GSX with a smoked RFI motor.

[RIDEH2O]

Re: Seadoo X4 1100 conversion build/resto

You dont need a girdled head....but they look cool. And who knows, you may need it later.

If the fuel pumps on the gpr carbs are good, you wont need externals. But you will need to tap a 3rd pulse line to run them. Im using the Rhaas plate myself. Go back a few pages on my build...PROJECT HX ((evil twin)) to see what I came up with....

Those 2 dudes you metioned....yeah, keep listening to them.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

You dont need a girdled head....but they look cool. And who knows, you may need it later.

I'd agree they do look cooler. What would require a girdled head? I could see one at higher compression ratios, but I'll never run over 30cc domes due to being sick of running race fuel constantly.

If the fuel pumps on the gpr carbs are good, you wont need externals. But you will need to tap a 3rd pulse line to run them. Im using the Rhaas plate myself. Go back a few pages on my build...PROJECT HX ((evil twin)) to see what I came up with....

Thanks. I'm going to run this plate with extra pulse lines.

Those 2 dudes you metioned....yeah, keep listening to them.

Agreed.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

New donor motor just showed up. I couldn't help myself. Had to try out the bling real quick lol.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

Decided to go for broke and have the case and cylinders ported. I've also decided on going with the Rhaas adapter plate with GP1200 carbs. It should save me a couple hundred bucks this route and provide almost the same performance as an aftermarket set.

Seeing as I've upgraded to an SPX baffle with 5/16" lines; do you think I need to run another line for the bigger carbs, or will this provide enough fuel?

[Scottie Mac]

Re: Seadoo X4 1100 conversion build/resto

Who's doing your port work? Judge is a friend of mine, if you want, I will check his availability. He's the best in the business.

SM

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

Who's doing your port work? Judge is a friend of mine, if you want, I will check his availability. He's the best in the business.

SM

I am having fullbore do it since they are doing the rebuild. I figured that was easier than shipping parts all over the place. I checked into a couple other places but they were 4 times the price. If this were a race ski I'd be more critical about who did it; but for rec use I am not super concerned as long as they don't hurt performance.

I would love to have Judge do it; but I'm afraid of what that might cost. I had a goal to keep this build at 3k and I'm already about $1,500 over that.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

I think I have the driveshaft conversion right in my head, but looking for input on it. Here are my thoughts:

Cut Kawi shaft end and thread. Cut Seadoo shaft end and thread. Have shop build threaded coupler to mate both halves together.

Does this look right? Does the shaft need to be supported where it's coupled together or is it short enough to not matter?

Can I measure the driveshaft length without the alignment tool? I have one coming but it's going to be a week out and I need to get this thing shipped off to fullbore pretty quickly if I want it back before summer ends.

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

I also have a question in regards to the extended pump housing.

The 95 XP's came stock with it and I'm thinking it would be a benefit to take advantage of it? Bill mentioned modded motors were prone to bending stock XP driveshafts due to the extra length so I'm thinking about using the driveshaft off of a 97 SPX (mated to the Kawi shaft) which was thicker and should take the abuse better.

Thoughts?

[Scottie Mac]

Re: Seadoo X4 1100 conversion build/resto

97 SPX didn't come with the spacer, so if you go that route, you won't be able to use the set back pump from the 95. The other option is to have skat build you one, but they are expensive!

AS for the porting, no matter who does it, make sure they know Kawis, especially 1100s, because you can't go in there and port like a normal Yamaha cylinder or you run the risk of cutting into the water jacket. If you have any questions, PM me.

SM

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

97 SPX didn't come with the spacer, so if you go that route, you won't be able to use the set back pump from the 95. The other option is to have skat build you one, but they are expensive!

Yeah, Skat is out. What do you mean about the spacer on the SPX? It's true they didn't use a setback pump on the SPX but why would it matter. All it means is the SPX driveshaft is a hair bit shorter than the 95 XP driveshaft; but seeing as I'm custom making one, I'd just have the Kawi shaft cut a bit longer to offset the difference. Am I missing something here?

AS for the porting, no matter who does it, make sure they know Kawis, especially 1100s, because you can't go in there and port like a normal Yamaha cylinder or you run the risk of cutting into the water jacket. If you have any questions, PM me.

SM

Thanks, I'll probably pick your brain a bit more regarding this going forward.

[Scottie Mac]

Re: Seadoo X4 1100 conversion build/resto

That set back kit on the 95 is like 4 inches, longer than stock, I was assuming you were just cutting the end off the shaft and having it done, but if you are making one, then yes, any of the XP/SPX shafts will work.

SM

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

That set back kit on the 95 is like 4 inches, longer than stock, I was assuming you were just cutting the end off the shaft and having it done, but if you are making one, then yes, any of the XP/SPX shafts will work.

SM

It's a shade over 5-1/2" longer.

What do you mean by cutting the end off the shaft and having it done? That's essentially what I will be doing.

Take a look at the pic of the driveshaft I posted yesterday and let me know if that looks correct. I am cutting the end off a 787 driveshaft as well as the Kawi shaft and mating them together with a coupler. Seems pretty straight forward unless I'm missing something?

[Alter Ego Trip]

Re: Seadoo X4 1100 conversion build/resto

Dp.