Air bubbles in fuel lines

[mejim707]

Ask yourself this....Do I really want to pull these again for the 25th time? Lol. I would never mix parts, to his eyes they might look great, to a pop off test they might look different. No, you need a 1.5 not a 1.2 or a 2.0, but the right one, the 1.5, that's why they make it. The needle is provably the same but the hole in the seat is different. It's really not worth the headache if you ask me. Literally what's another weekend or 2 until you get the right stuff. I know weekends are scarce, weather, blah, blah, blah. I'd rather my boat be top notch. Sorry to sound negative, but that's my opinion.

I totally agree. Thats why I was asking. Looking at the brass seat they're different sizes. I went ahead and bought new genuine needle / seats from amazon. They'll be here by tuesday. Have to do this stuff right and that guys is suggesting a total hack job. He even said you don't need to do pop off tests and throw away your pop off tester lol... Wow

 

[noviceskier]

I totally agree. Thats why I was asking. Looking at the brass seat they're different sizes. I went ahead and bought new genuine needle / seats from amazon. They'll be here by tuesday. Have to do this stuff right and that guys is suggesting a total hack job. He even said you don't need to do pop off tests and throw away your pop off tester lol... Wow

which is why I prefer to work on my own machines

 

[Sportster-2001-951C-Stock]

You definitely need the correct seat orifice diameter, your low speed fuel calibration depends on this. The needle tips are the same, to my eyes.

Have a google search for the Mikuni SBN manual PDF, in this free manual they explain the philosophy for orifice diameter selection.

 

[mejim707]

You definitely need the correct seat orifice diameter, your low speed fuel calibration depends on this. The needle tips are the same, to my eyes.

Have a google search for the Mikuni SBN manual PDF, in this free manual they explain the philosophy for orifice diameter selection.

I’ll definitely read up on this. I do have the correct 1.5s on the way.

One nice thing is it seems very easy to adjust the LS and HS. 1 turn out on the LS and 0 on the HS seems simple enough haha

I have a very good feeling about this next trip out.

 

[Sportster-2001-951C-Stock]

The adjustment of the HS and LS mix screws can vary from model to model and even year to year in some cases. seadoosource dot com has posted a reasonable table of these along with a host of helpful notes.

 

[mejim707]

The adjustment of the HS and LS mix screws can vary from model to model and even year to year in some cases. seadoosource dot com has posted a reasonable table of these along with a host of helpful notes.

Indeed! I did check that chart as well and thanks for the link. According to @SeaDooSource the 96 single 787 challenger engine is the same as the 1996 XP, GTX and GSX. Looking at the parts diagram below the MAG and PTO carb part numbers are; MAG 270500284 and PTO 270500285. When I reference them on the chart I see turns out as "LOW - 1, HIGH - 0" for the GTX, GSX and XP.

The repair tech at the local shop, who suggested two different needle and seats , said LOW - 1 1/4 and HIGH "just a crack" as he pointed to his butt...

Does this seem right to you or was he just trolling me? Maybe this will give the 787 some added performance or no? Not sure on this front but I'll lean on the experience of this group here for advice in this matter.

I know that the other day the boat felt like it wanted to just goooo. My sister and brother in law were with me and she was freaking out because the waves were pretty bad so I couldn't open it up. Zero hesitation however when I gave it some throttle! But, after an hour of 1/2 to 2/3 throttle it started to feel like the engine was getting loaded up. Slow speeds through the no wake zone back to the launch seemed smooth. And even idling around the launch waiting for an opening seemed fine. But, once I cut the engine for a few minutes I could not start it. Backup plan of oars on board did the trick lol. I also carried the trolling motor just in case I was way out there.

Once I get the new needle and seat I think the loading issue will be resolved. And the no start after a few minutes of sitting. Getting there fellas.. Thank you!

Chart: Sea Doo PWC Carburetor Reference
Parts Diagram MAG: 1996 Sea-Doo Challenger, 5896 Carburetor MAG | Fox Powersports Sea-Doo Partshouse
Parts Diagram PTO: 1996 Sea-Doo Challenger, 5896 Carburetor PTO | Fox Powersports Sea-Doo Partshouse

 

[mejim707]

BTW, updated pop off tester per suggestions. I could not find a gauge anywhere local that was max 60 psi. But, I had a tire gauge that read 60. A quick trip to Lowe’s got me the two adapters I needed to fit it. Works great!

Also the MAG carb holds 10psi indefinitely when fully assembled! I’ll check the PTO tomorrow.

 

[mikidymac]

A stock Seadoo will run perfectly with the carb settings from the book. If it doesn’t you have something wrong. Do not trust that mechanic for anything he obviously doesn’t have a clue.

 

[Sportster-2001-951C-Stock]

Yes, just start with the book settings. If you have to deviate the simple answer is something's wrong.

BTW, when checking compression, I ground my plug wires as opposed to taping them off. It's not the end of the world if you don't, just good practice. See here for more:

Grounding spark plugs – Antique Outboard Motor Club,Inc

 

[Sportster-2001-951C-Stock]

Keep in mind that that one gallon of oil to 50 gallons of fuel is about what it should use at higher throttle settings and this is a variable rate system. At half throttle or idling around you will use far less than that... My Speedster for instance has a 2.5gal oil tank and I’ll go through seven or eight 26gal tanks of fuel before I have to even think of refilling it.

This is quite right from the perspective if you're just putting around maybe pulling a tube or something as many of us do as opposed to running WOT plug chops all day, you tend to use less oil.

Best I can account for, based on my rough measurements of consumption and the style I run my boat, bla, bla, my consumption is about 50:1 I did my best to keep track, I may have made some error, one way or another only b/c I'm not Mr. Perfect.

 

[Sportster-2001-951C-Stock]

after an hour of 1/2 to 2/3 throttle it started to feel like the engine was getting loaded up. Slow speeds through the no wake zone back to the launch seemed smooth. And even idling around the launch waiting for an opening seemed fine. But, once I cut the engine for a few minutes I could not start it. Backup plan of oars on board did the trick lol. I also carried the trolling motor just in case I was way out there.

Once I get the new needle and seat I think the loading issue will be resolved. And the no start after a few minutes of sitting. Getting there fellas.. Thank you!

Agreed, this sounds like the metering needle(s) was leaking fuel.

 

[mejim707]

Quick question, if there are no rips in the carb base gaskets, and they're new as of a few weeks ago, can I reuse them? I've pulled the carbs three times already. The first time I replaced the gaskets with the new ones. There's nothing wrong with them that I can see so should I replace them every time I pull the carbs? I'm hoping I won't have to do this again for a while.

Also, what is the torque spec for reinstalling the carb bolts? I'm going to look in the shop book as well.

Thoughts?

 

[mikidymac]

I would not suggest reusing carb base gaskets. You do not want an air leak there.

 

[mejim707]

I would not suggest reusing carb base gaskets. You do not want an air leak there.

You’re right. I won’t risk it. Unfortunately nobody around has them in stock. I may entertain hitting autozone for gasket paper and cutting my own. Have you done that before? I mean the paper used looks like pretty general gasket material.

 

[mejim707]

I dunno, I got this gasket paper for use with oil fuel and coolant. It’s slightly thicker than the green paper gaskets. I would imaging this should work if I trace the current gaskets and cut to size. I saw a post some place that suggests this is ok to do.

Thoughts?

 

[JeremyD615]

I don’t see any issues with the Fel-Pro stuff. I’ve used it many times for automotive stuff, and it’s as least as good quality as the factory BRP gaskets...

 

[mejim707]

I don’t see any issues with the Fel-Pro stuff. I’ve used it many times for automotive stuff, and it’s as least as good quality as the factory BRP gaskets...

Awesome! I’d obviousely prefer to get the OEM ones but the availability is scarce and if the quality of the material is as good as OEM I can simply enough make my own.

 

[mejim707]

Ok, looks decent!

And I guess I have enough for a few more lol

 

[JeremyD615]

I think you’re good to go with those. They look as good or better than most of the manufactured gaskets... Plus it reminds me of making gaskets the old school way with a sheet of paper and a ball peen hammer!

 

[mejim707]

I installed the new needle and seat kits. The MAG pops at 28 and the PTO at 30.

At fist the PTO was popping at 35 and dropping 10 pounds until it seated. This did not happen on the MAG side. Does it take some time for the kits to ‘break in’? The PTO side is sealing right away now.

Also, I pressurized the MAG side to 10 PSI days ago and it held its pressure for days even with the old needle and seat kits.

 

[robing]

Its tricky stuff. The rebuild is straight forward, but the results always vary. I did mine 4 years ago and could never get pop off perfect. I'm about to rebuild them again, really hope it goes smoothly.
That bieng said, could you tell me where you got your rebuilt kits and needle and seat?
Like your gaskets.

 

[mejim707]

Its tricky stuff. The rebuild is straight forward, but the results always vary. I did mine 4 years ago and could never get pop off perfect. I'm about to rebuild them again, really hope it goes smoothly.
That bieng said, could you tell me where you got your rebuilt kits and needle and seat?
Like your gaskets.

Well, I got the genuine rebuild kits from Land and Sea in Waterbury CT. It was $55 a pop! Crazy.. but they’re genuine and that’s most important.

The needle and seats I got from Amazon. @mikidymac posted the parts on the previous page.

I’m going to mess with the pop off more tomorrow. I won’t cut any spring but I will slightly bend the arm down / up to dial them in. It’s a very slight bend and I’m aiming for a true 30 PSI on both. Time to get OCD on these babies!

Thanks about the gaskets. It’s easy to do. Take your time if you decide to make some.

 

[mikidymac]

You want them as close as you can get them but if they aren't exact you will be fine. At 28 and 30 you are good but bend one arm up 1mm and one down 1mm and they should both be at 29 and job done.

Also remember pop-off is just a test and isn't how the carbs actually work when running. This coupled with each cylinder being a little different and the carbs not being exactly synched 1 -2 psi isn't going to make a difference.

But I am OCD also so I like them as close as I can get. I even will wait to put the cover on until both are done because I have even swapped arms and springs between the two to get them exactly the same. And no. I haven't noticed a difference between a skit that they were perfect and one that was a couple psi off.

 

[mejim707]

You want them as close as you can get them but if they aren't exact you will be fine. At 28 and 30 you are good but bend one arm up 1mm and one down 1mm and they should both be at 29 and job done.

Also remember pop-off is just a test and isn't how the carbs actually work when running. This coupled with each cylinder being a little different and the carbs not being exactly synched 1 -2 psi isn't going to make a difference.

But I am OCD also so I like them as close as I can get. I even will wait to put the cover on until both are done because I have even swapped arms and springs between the two to get them exactly the same. And no. I haven't noticed a difference between a skit that they were perfect and one that was a couple psi off.

Great thanks. I'm going to mess with them a bit more tonight. One issue, the PTO carb I pumped to 10PSI and it dropped 5PSI over night. I need to figure out where that leak is coming form. The MAG held 10PSI for 3 - 4 days straight.