947 Sportster build

[951 or bust.]

Building a 951 for my Sportster, soon to have all my pieces back from the machine shop.
and start re assembly. LA sleeves were on back order for the longest time as I was told from my machinist, or else this build would of commenced during the winter months like I planned.

New LA sleeves pressed into the jugs at 88mm bore running reman seadoo crankshaft and reman seadoo counter balance as advised by many members here.
WSM pistons and factory gaskets. about to order back to OEM kits for the carbs from OSD marine and rebuilding them as the old motor was bored and the carbs were all messed with.

Now onto the cylinder head, I'm looking into ordering a new Miller head from https://www.ronsperformanceshop.com/ what size Domes should I be going with for a rebuild engine at factory specs. 88-89 bore 951 engine domes available 42cc 44 cc 47cc 49 cc
will be running ultra 94 pump gas and factory oil injection system as recommend here from many members.

Thanks,
Daryl

 

[mikidymac]

To be honest, I wouldn't be running a high compression head with WSM pistons. They are fine for a stock rebuild but a 951 is already highly stressed and adding more compression will not help things. For a performance 951 you really want either OEM or Pro-X pistons.

What reman crank did you buy?

Make sure to follow the manual to the letter on reassembly and use Threebond 1184 or equal on the cases and OEM crank seals.

 

[951 or bust.]

To be honest, I wouldn't be running a high compression head with WSM pistons. They are fine for a stock rebuild but a 951 is already highly stressed and adding more compression will not help things. For a performance 951 you really want either OEM or Pro-X pistons.

What reman crank did you buy?

Make sure to follow the manual to the letter on reassembly and use Threebond 1184 or equal on the cases and OEM crank seals.

The Machinist told me the OEM pistons are wildly overpriced, I didn't check into this myself. I'm in Canada but if I Remember correct he was saying over 200 a piece plus rings are extra. I'll call him today or Tuesday and ask about pro X. I'm surprised he didn't recommend then to me.... his recommendation was WSM he said he would get Me an OEM crank and counter balance as I specifically asked for them.

Hypothetically if I go with pro X piston I would then be able to run which domes? are pro X forged or cast aluminum?

Appreciative of all the help and guidance!

 

[mikidymac]

You would have to talk to the person making the head to see what domes would be fine for pump gas.

OEM pistons are $92 US each and come with rings.

Pro-x are cast pistons just like OEM.

What is this engine going in?

 

[951 or bust.]

You would have to talk to the person making the head to see what domes would be fine for pump gas.

OEM pistons are $92 US each and come with rings.

Pro-x are cast pistons just like OEM.

2000 seadoo sportster jet boat, I know not many people modify the boats. that iv seen but id like to do some stuff.

 

[mikidymac]

It's a heavy boat for an engine originally made for a lightweight ski. The only thing adding more compression will do is give you a little more bottom end which you really won't notice in a boat.
Honestly I wouldn't waste the time, money and headache for more compression on that.

 

[951 or bust.]

It's a heavy boat for an engine originally made for a lightweight ski. The only thing adding more compression will do is give you a little more bottom end which you really won't notice in a boat.
Honestly I wouldn't waste the time, money and headache for more compression on that.

Ok good to know, i'll just try and source a factory head then and go for a reliable engine. what about a new impeller? for a bit more power ? or torque due to the weight you mentioned

 

[mikidymac]

Seadoo did a really good job of selecting the OEM impellers. Probably the best thing you can do is check the condition of your impeller and wear ring and make sure they are perfect.

 

[951 or bust.]

Seadoo did a really good job of selecting the OEM impellers. Probably the best thing you can do is check the condition of your impeller and wear ring and make sure they are perfect.

glad to hear that! ok I'll get this thing together and running.
work out all the kinks and see what I can do.

Thanks for your help

I do have a printed manual for a 99 gtx limited with 951 silver engine that I will follow for the rebuild, any other changes from the manual for sealants or procedures that I should note will use the threebond 1184 as recommended and follow your carb rebuild guidelines

 

[mikidymac]

Use all the other sealants and loctite the book recommends. THe only one I don't follow is the case sealant and even seadoo changed that spec. The ThreeBond 1184 is also sold as Yamabond, Hondabond, and Motoseal.

 

[951 or bust.]

Sportster update, I'll keep this "build thread" updated as I make progress.
If this isn't in the right place mods can be free to move it.

This Saturday I will be rebuilding my carb's as per Mikidymac's how to write up,
I've gathered all the proper new components to re connect my Mikuni oil injection system, all new lines, new filter, brand new oil pump, new tank grommet and tank elbow. Cleaned the tank and she;s ready to fill with oil when the time comes.
I've purchased this oil as pictured below let me know if this is the right stuff, I only ask as there is no numbered spec on it from what I can see.





My boat has an aftermarket lowrance mark 4 HDI connected to it so there is a transducer on the back of the hull. seen from the picture below the old owner just hacked the wire install. Is there a special threw hull grommet I can use to seal this hole!!!! it looks absolutely horrible. I don't even want to float the boat until this is fixed if that silicone lets go water will be rushing in!



Any fixes for Broken bucket cables, the sheathing has broken. I assume the fix is a new cable.. Best place to source?? SBT has it for 145 USD plus shipping and duty as I'm in the states. I've put out some feelers local but have yet to hear back.


As always the help is much apricated!

 

[mikidymac]

Yes that’s the good oil.

Cable has to be replaced.

Hull can be repaired with MarineTex.

 

[951 or bust.]

Yes that’s the good oil.

Cable has to be replaced.

Hull can be repaired with MarineTex.

Miki, MarineTex would work. but then i would have to still drill a hole after to run the cable.
but I'm thinking something along the lines of grommet? or cable gland or passthrew grommet or would that be a bad idea? https://www.defender.com/category.jsp?id=2289996&path=-1|328|2289986

 

[mikidymac]

Best sealant for a cable hole under the waterline is 3M 5200.

 

[951 or bust.]

Today I performed carb rebuilds on both carb's following miki's how to thread, using all Genuine mikuni parts from osd marine. everything went well. just have a few follow up questions.

1; how rare is it to have a round diaphram on your accel pump, I inspected the accel pump before ordering all parts and the pump visually looked square. so I assumed as a idiot it was the square diaphram... well lone behold its a round one.... silly me.
2; pop off spec for this carb is 19-23PSI (as I seen in the how to thread) I'm having both pop off right at 20PSI running 2.0 needle and seats, 162.5 main 75 pilot Jets sounds good? or should I adjust higher?
note when I disassembled carbs they had what looked to be 65 gram shiny silver springs. and were popping at 18 PSI. I used the brand new springs in my OSD kit that are 95 gram dull silver springs and am getting the 20PSI on both carbs.
3; when checking pop off on the fuel pump carb it worked fine but when I did a pressure test it was slightly leaking from a carb nipple pictured here with the yellow cap on it. (note picture)
both milar discs are placed in correct with the painted line facing up.

you can see here I'm holding the fuel tee on the left side of the photo, and the pop of tester is on one nipple and the yellow plug is on the other. the carb then holds 10 PSI for 10 min.
am I testing this proper?

painted line is upward.

Painted line is upward.

the carb in question. other carb went with no issues.

both carb's are running 1 1/2 turns out on low speed screw. and the high speed is at 0. ran it down till it bottomed out and then just slightly turned it out like the littlest bit. sounds good???

Thanks!!

 

[951 or bust.]

All I'm hearing is crickets? nobody has insight into above #15 post? Even the carb guru's?

 

[mikidymac]

Your popoff is good.

 

[951 or bust.]

Happy may 24 weekend too all!! Boat is still a few weeks from being splashed. parts are now in from machine shop finally starting assembly of engine.

 

[951 or bust.]

Hello fellow Jet boaters, conundrum with my throttle cable. It's broken and needs replacement. I have a 2000 seadoo sportster, when I look up the throttle cable in the parts catalog it give me 204390187 this cable doesn't look like mine. I have this cable 204390186 what is the switch for on this cable? and why in the parts catalogue is my boat calling for the cable without a switch?


204390187



204390186