Looking for Correct Part# and Suggestions for Carb Rebuild Kit, 1997 GSX

[Frank_Hassa]

While looking through the "seadoo-1988-2003-specifications" pdf I downloaded from seadoomanuals(dot)net, I found this:

View attachment 37152

Which says I have 2 Mikuni BN-40i carburetors, and I want to make certain this is correct before I spend money on rebuild kit(s).

Edit: I just realized that it's a BN-40i, and not a "1" like what I originally thought. Figured I'd mention that in case the next person also makes the same mistake.

And also any recommendations on vendors, specific kits, OEM vs. aftermarket, etc...

Second, it also says that the "Main Jet" is "142.5" and I have NO idea what this means. Is 142.5 a diameter? Pressure? Some kind of setting? Flow? No clue. I assume the "jet" they are referring to is the jet in the carburetor where fuel comes out, but I'm not even certain of that. Maybe it's the jet pump, having to do with water?

My focus is doing a carburetor rebuild, so my main question is, does this "jet" number have anything to do with it?

 

[jcleary93]

You must go with a genuine mikuni kit. The aftermarket are garbage

 

[soccerdad]

The 142.5 is related to the hole size in the jet. They are clearly stamped on the jet. You should not have to worry about it. You just reuse the ones in your carbs. Just remove the carbs and open them up one at a time on a tray like a cookie sheet. Take some pictures along the way so you know how they go back together. DL the carb manual. It should help you. http://www.mikuni.com/pdf/sbn_manual.pdf Make sure you reuse the spring for the needle and seat assembly. Do not use the springs from the kit. You will have extra parts from the kit left over. This is normal. Go slow. It is not that hard. Be careful on the internal screw. They like to strip out the heads. Since you are doing two sets, I would invest in a JIS screwdriver https://www.amazon.com/Vessel-Ball-...s=jis+screwdriver&refinements=p_85:2470955011 It is only a couple of bucks and will save you a lot of grief. The screws look like Phillips, but they are really JIS. [MENTION=41828]Minnetonka4me[/MENTION] will make sure you get the correct kits if you get them from him. He also is a great source for the small oil line and oil filter and valve if you are changing them.

 

[wfo speedracer]

I second the JIS screwdriver, it's one of the best tools I have ever purchased.

 

[amaynard]

I just purchased an oem mikuni kit from ebay. Worked out great. Little overwhelming since it has extra parts galore. Price was kinda steep. 89$ for 2 carbs and fuel pump. After some deep reading oem seemed the way to go
Winderosa sell them for 50 to 60$. From what I've read go oem. Especially with the fuel diaphragm

 

[amaynard]

Check out seadoosource.com. Tons of good info

 

[amaynard]

Thats the exact one I ordered.

 

[amaynard]

http://www.seadoosource.com/mikunitests.html read this before hand a few times

 

[Frank_Hassa]

I just purchased an oem mikuni kit from ebay. Worked out great. Little overwhelming since it has extra parts galore. Price was kinda steep. 89$ for 2 carbs and fuel pump. After some deep reading oem seemed the way to go
Winderosa sell them for 50 to 60$. From what I've read go oem. Especially with the fuel diaphragm

Thats the exact one I ordered.

I couldn't find yours, but then I don't know if yours is supposed to be the same as mine. I have a 1997 GSX.

I found this one:

http://www.ebay.com/itm/SeaDoo-787-...ash=item281808129b:g:W5MAAOSw8vZXMn11&vxp=mtr

Similar price. Says "Genuine". Has the familiar packaging. But.

BUT.

But it offers to sell you the "fuel filter" as an add-on, which seems straight-up retarded and dishonest to me, given the widespread failure of the factory fuel lines, there's no other reason to rebuild the carb except to get rid of whatever dissolved fuel line crud might be in the fuel filters. Someone told me there's no inline fuel filter, so there's only one fuel filter and that's internal to the carbs. Why sell a rebuild kit without the fuel filters. The aftermarkets have fuel filters at half the cost.

Second this vendor also offers to sell you the carburetor "base gasket" which I assume is the big gasket that interfaces the carb to the engine. Seems like including that one is also a no-brainer. And then there's jets and seats which I haven't read much about, but still.

 

[racerxxx]

Look at the part number the mk-bn38/44spr that is what you want. The only difference in carbs is the latter ones have an accell pump, which isn't included in that kit or any for that matter. The little filters are in that kit. You don't need the jets, you do need the needle and seat, which is extra anywhere. The fuel filter he is offering is an external one to put inline before your carbs. He's not being dishonest, he's offering you a one stop shop, like the oil pump block of kit. You're reading too deep into it.

 

[gazza2010au]

There were some discussion a long time ago about the internal carb filters some guys were running with some running without them, people were complaining about them being internal and a pain in the ass just to clean

For me i would replace them as its only plastic i can't remember if the plastic breaks down over time but if your doing the carb overhaul i'd replace them

Thanks for the tip on the screw driver i've had those screws strip before :redface:

 

[soccerdad]

Look at the part number the mk-bn38/44spr that is what you want. The only difference in carbs is the latter ones have an accell pump, which isn't included in that kit or any for that matter. The little filters are in that kit. You don't need the jets, you do need the needle and seat, which is extra anywhere. The fuel filter he is offering is an external one to put inline before your carbs. He's not being dishonest, he's offering you a one stop shop, like the oil pump block of kit. You're reading too deep into it.

+1 And the carb base gaskets are not part of any kit that I know of. It is not a scam, it is just how it is done. I often reuse carb base gaskets if they are in good condition. I put a thin layer of grease on them and reuse them. Some will never do this, others do. It works for me. YMMV. You will find that most of this industry is straight forward and honest. The only reason people steer you away from some items and recommend others is that most of us have been burned by a bad "new part". You can use many non-OEM parts with fantastic performance and a better price. But certain items just make sense to buy OEM stuff. Yes the carb kits are pricy, and so are the needles and seats. You can find the carb kits all day long for $45/carb. You will be out about $130 for all of it to do one ski. BUT, if you take your time, and do it correctly, you will have perfect running ski, that starts every time and lasts for years. The carbs are the most important part on a ski. Done wrong you will either have a blown motor or you will be sitting on the dock trying to get it to start. Done correctly, just pull the choke, hit the starter and go ride with a big smile on your face. Again, the job is not that hard. Take your time, use the correct parts and pay attention to the details. Read the carb sticky at the top of this forum section. Good luck.

 

[Frank_Hassa]

Yeah, I'm wound a bit tight as this whole project is WAY bigger than I thought it was going to be. I've spent entire days doing almost nothing but researching this stuff.

So today I changed-up my search terms a bit and found this:

http://www.ebay.com/itm/OSDmarine-S...ash=item3aca4014ce:g:0nsAAOxyIPNTejfS&vxp=mtr

1) It's genuine Mikuni, particularly the diaphragm.
2) It includes the jets and seats.
3) It includes the base gasket
4) It's a dual-carb kit

There's a statement of the Vendor's assurance of a commitment to quality that sounds almost exactly like what everyone here says; that a low-quality and imprecise diaphragm will cause all sorts of problems, and the price is comparable to other genuine kits that do not have the jets & seats or base gaskets, and this has all of it, and the Vendor assures at least the important parts are OEM.

It sounds too good to be true, so I"m asking. Is it good, or too good to be true?

He also says that if you re-use the factory original springs, a pop-off test is not necessary. I'd like to take at least one "extra" off the list. The special JIS screwdriver, etc.... I'm also wanting to put a inline fuel filter prior to the carbs, to protect the internal filters and maybe not have to open them up and clean them again.

Is there any reason to not:

1) Do the pop-off test (really, buy or build the tester)?
2) Add an inline fuel filter?

 

[1983]

no i would not buy that kit

from the ad:

"Includes Two (2) NEW 1.5 Aftermarket Needle Valve Assemblies"

you want OEM mikuni needles and seats.

you cant take shortcuts on carbs, nor near anything else on these boats. But especially the carbs.

OEM mikuni all the way.

Yes you can reuse pop off springs if the pop off test results are nearly the same psi number or within 1 psi of each other, and they are within spec for the model of your engines carbs.

 

[racerxxx]

If you order direct from osd you can get the oem needle and seat

 

[amaynard]

I wouldnt replace the needles and seats unless they are really screwed up. Imo if you use oem kits and the exact same spring or a oem replacement pop off should be good. To be safe you could pull them off and look carefully to see the number. I believe its 1.5 for yours with a 95gram dull silver spring. Ill find the chart and post it

 

[amaynard]

http://www.seadoosource.com/carbreference.html

 

[amaynard]

If your going to test thr pop off google diy pop off tester. Lot cheaper then the seadoo one

 

[soccerdad]

I wouldnt replace the needles and seats unless they are really screwed up. Imo if you use oem kits and the exact same spring or a oem replacement pop off should be good. To be safe you could pull them off and look carefully to see the number. I believe its 1.5 for yours with a 95gram dull silver spring. Ill find the chart and post it

You may get away without replacing the needle and seats. But if they leak, you will end up with hard hot start issues. And then have to pull them apart again. I did it that way on my first ski. And had to do them all over again. (at least open them up). I get that the costs add up fast, but compared to a new ski, these are dirt cheap.

 

[wfo speedracer]

Personally I never buy the kits, they are overpriced and contain lots of parts that don't need to be replaced and they do not contain some parts that do, I just order the individual parts.

 

[Frank_Hassa]

Personally I never buy the kits, they are overpriced and contain lots of parts that don't need to be replaced and they do not contain some parts that do, I just order the individual parts.

So you tear down both carbs and decide what you need to replace at that time? I was pricing the fuel diaphragms by themselves and OEM diaphragms are $15, and you can get the whole kit for $45. I assume that the fuel filters are assumed to be dirty and also that if they are dirty you replace them and do not try to clean them. So at minimum we're looking at fuel filters and a new fuel diaphragm as a minimum "kit", right? And I've a history of shredding carb base gaskets on removal and am inclined to just replace the old one whether it needs it or not.

The thing that makes me nervous about this idea is the idea of having both carbs disassembled and laying around waiting for parts to come in.

What's your source for individual parts?

 

[gazza2010au]

You should never pull a part a carby and leave it sitting around waiting for parts as there are a lot of small pins,springs,seats,screws,gaskets u can lose track of

u ideally rebuild the carb's because once u pull it a apart u stretch the old rubber gaskets and seals

 

[mikidymac]

Genuine needle and seats are $15-$16.25 each on Amazon.
The ones on ebay are fine as long as they are Genuine.
I always replace the base gaskets.

If you just want the individual parts contact minnetonka4me here or OSD Seadoo Parts.

Do not use the new springs in the kit.

I always check popoff. You would be surprised how often you find an issue and I have been doing these for 20 years. Damn, has it been that long?

 

[wfo speedracer]

So you tear down both carbs and decide what you need to replace at that time? I was pricing the fuel diaphragms by themselves and OEM diaphragms are $15, and you can get the whole kit for $45. I assume that the fuel filters are assumed to be dirty and also that if they are dirty you replace them and do not try to clean them. So at minimum we're looking at fuel filters and a new fuel diaphragm as a minimum "kit", right? And I've a history of shredding carb base gaskets on removal and am inclined to just replace the old one whether it needs it or not.

The thing that makes me nervous about this idea is the idea of having both carbs disassembled and laying around waiting for parts to come in.

What's your source for individual parts?

No I have the individual parts in stock to repair whatever I need to repair, yes I could take all the parts throw them in a bag and reassemble the damn things blindfolded, it's really not that hard. I am a WSM and WPS dealer, Parts Unlimited and Hot products also have all the individual parts in stock.

 

[Frank_Hassa]

Update:
I haven't done much, but I did buy 3 buzzers (one for each Seadoo and one as a spare) for $8.00 each at Radio Shack. Have not tested or installed them yet.

MAJOR advance was that I poured about a Tablespoon of gas down each spark plug hole and put the plugs back in and it fired up! Did it a 2nd time and it also ran for a few seconds. So I assume that rules out the possibility of major damage to the engine. (As a reminder, this SeaDoo has been neglected in the previous owner's yard for 13 years.)

I have a bunch more questions but they are very specific so I'll start separate, smaller threads for them.

Genuine needle and seats are $15-$16.25 each on Amazon. The ones on ebay are fine as long as they are Genuine.
I always replace the base gaskets. I always check popoff. You would be surprised how often you find an issue and I have been doing these for 20 years. Damn, has it been that long?

Why replace needles and seats? The gauge says it has about 110 hours use. Do they corrode? Wear?

Another "General" type of question:
I've read about people running these Seadoos out of the water without any water flowing through the engine. Today I note there's a water line going through the manifold? I assume to keep the engine cool. Do I need to worry about overheating due to lack of water while working on the Seadoos on the trailer?