Thats what I thought, I guess I'm looking into getting another carb to replace it. I can't wait to fix all these simple stupid problems I inherited. Out of all the used motorcycles and cars Ive never had this many issues. I hope there aren't many more. I still have yet to make sure the cavitation is fixed as I have replaced wear rings, installed new solas implellers, and all drive line rebuild kits with carbon rings, seals, all that crap.
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Well now what can I do?
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Thats what I thought, I guess I'm looking into getting another carb to replace it. I can't wait to fix all these simple stupid problems I inherited. Out of all the used motorcycles and cars Ive never had this many issues. I hope there aren't many more. I still have yet to make sure the cavitation is fixed as I have replaced wear rings, installed new solas implellers, and all drive line rebuild kits with carbon rings, seals, all that crap.
Sportster-2001-951C-Stock
Well-Known Member
There shouldn't be any oddball inexplicable differences in your carbs, not sure what's up with that.
But I see we've neglected to inform you of the standard rules for Seadoo engine MAINTENANCE:
Give Her a good Going Over at regular intervals.
Grease Her NIPPLES well.
When Running Her in, break Her in GENTLY!
Her CLUTCH Should not be too 'Hairy'.
Wax Her BODY all over.
If you should strike Her REAR END – say 'Sorry'
Check Her Load Bearing capacity, too much weight can impede her, PERFORMANCE
If She loses Her 'SPARK', she may be suffering from high TENSION troubles.
Never take Her too fast up the 'Straight'...warm her up GENTLY first
Keep Fingertip Control at all times.
Her 'BIG ENDS' should be kept Well Oiled!
Don't leave Your TOOL hanging about.
Give her a Re-bore when necessary... and a Good Grind -In!
If She sags when Climbing give Her a Boost, and see if She's got any GOOD POINTS!
Check Her BODY for Blemishes -and Touch Her Up where necessary.
Remember – IF YOU CAN’T GET IT IN FIRST…Just wiggle it about, its bound to slip in sooner or later
Sportster-2001-951C-Stock
Well-Known Member
Does that mystery adjuster have a check ball and spring inside it? If yes, then it's a rev limiter device.
But even so, that "adjuster" is not found on the Mikuni BN carbs as far as I know and the o-ring around it doesn't even seem to fit it correctly. Looks like someone has goofed up the carb but that adjuster looks like the old rev limiters they used to put in 2-stroke carbs that we always disabled by soldering shut to allow adjusting WOT mixture. If it has a spring and check ball it's supposed to rattle the check ball off it's seat beyond a certain RPM and cause the fuel mixture to go pig rich. A mechanical fuel mixture rev limiter. Normally those were in their own circuit that bypassed to the main venturi. We used to solder them shut so we could hear the engine rev and adjust the HS mixture so unloaded it wouldn't rev, but 4-stroke instead (the proper way to adjust 2-stroke WOT mixture). We couldn't do that when those silly rev limiters were screwing with the fuel mixture... so we disabled them.
Here are a few other special parts you might find on that ski:
But even so, that "adjuster" is not found on the Mikuni BN carbs as far as I know and the o-ring around it doesn't even seem to fit it correctly. Looks like someone has goofed up the carb but that adjuster looks like the old rev limiters they used to put in 2-stroke carbs that we always disabled by soldering shut to allow adjusting WOT mixture. If it has a spring and check ball it's supposed to rattle the check ball off it's seat beyond a certain RPM and cause the fuel mixture to go pig rich. A mechanical fuel mixture rev limiter. Normally those were in their own circuit that bypassed to the main venturi. We used to solder them shut so we could hear the engine rev and adjust the HS mixture so unloaded it wouldn't rev, but 4-stroke instead (the proper way to adjust 2-stroke WOT mixture). We couldn't do that when those silly rev limiters were screwing with the fuel mixture... so we disabled them.
Here are a few other special parts you might find on that ski:
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Waterluvr
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Good call, you can bet that heavy handed move that crushed the needle tip down on the seat damaged the circuit's ability to flow and you really don't want your motor leaned out on account of it at WOT. It may adjust ok but since you're new to that particular carb and motor combo and turning your own wrench it would be wise to stick close to the fat side of the factory settings until you have some more time under your belt learning to tune.
You don't want the old saying it runs the best it ever did right before it died for good to come calling from a leaned out top end, sounds like you have enough work all in as it is.
Sportster-2001-951C-Stock
Well-Known Member
Looks to me like the needle tip isn't smashed, just lightly corroded a bit, it's fine.
If you take a piece of wire about 0.20" diameter and insert it down into the HS mix adjuster hole, are both carbs the same depth?
If you take a piece of wire about 0.20" diameter and insert it down into the HS mix adjuster hole, are both carbs the same depth?
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Well after doing a lot of research and looking at a lot of pictures and I come to the conclusion that a lot of people are saying there is no difference between the 717 and the 720 carbs but every picture I see the 717 fuel feed/return are straight and the 720 fuel feed/return are at a 90deg angle. This makes me think there is also a difference in the "H" adjuster. I have a used carb coming so hopefully that is the correct 717 carb.
Sportster-2001-951C-Stock
Well-Known Member
The 717 actually has a displacement of 718.2cc and is often referred to as the 720.... Same motor as far as I know.
The 787is often referred to as the 800, it has a displacement of 781.6cc
The 951 is sometimes referred to as the 947, displacement is 951.2cc
The purpose is to create confusion!
Oh, maybe since I think the 720 was fitted with both a single carb intake and dual carb intake this might be causing some confusion? I don't know which version you have but the carb should have a number casting on it somewhere? Not sure which you have, maybe the SBN40i or SBN-40 model?
I've forgotten exactly which carbs were on my old '95 seadoo, I think that was the 717 motor and it had two carbs so maybe the SBN40's were on it but don't recall them being the "i" improved fuel pump..... It's been many years and honestly they all start to look the same once you've wrestled with so many.
Your boat might be single carb, I think those may have beeen......
The 787is often referred to as the 800, it has a displacement of 781.6cc
The 951 is sometimes referred to as the 947, displacement is 951.2cc
The purpose is to create confusion!
Oh, maybe since I think the 720 was fitted with both a single carb intake and dual carb intake this might be causing some confusion? I don't know which version you have but the carb should have a number casting on it somewhere? Not sure which you have, maybe the SBN40i or SBN-40 model?
I've forgotten exactly which carbs were on my old '95 seadoo, I think that was the 717 motor and it had two carbs so maybe the SBN40's were on it but don't recall them being the "i" improved fuel pump..... It's been many years and honestly they all start to look the same once you've wrestled with so many.
Your boat might be single carb, I think those may have beeen......
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Sportster-2001-951C-Stock
Well-Known Member
So those are single carb motors, not dual, correct?
Yeah, no telling where that goofy carb came from, maybe someone stuck a junk carb on there?
I'd want to get identical carbs on both motors though, IMO. And while they're all apart check the high and pilot transition jet sizes, pop spring color, and metering seat orifice size to make sure the replacement carb is configured the same as your good carb.
I see your accelerator nozzles aren't connected to the accelerator pumps either.... Are you planning on using them? If not the calibration (pilot transition jet size) needs to take that into account.
Aside: Pilot jet = Transition jet, same thing but better description. Mikuni is a Japanese company... Very good carbs but they aren't grand masters of the English language.
Yeah, no telling where that goofy carb came from, maybe someone stuck a junk carb on there?
I'd want to get identical carbs on both motors though, IMO. And while they're all apart check the high and pilot transition jet sizes, pop spring color, and metering seat orifice size to make sure the replacement carb is configured the same as your good carb.
I see your accelerator nozzles aren't connected to the accelerator pumps either.... Are you planning on using them? If not the calibration (pilot transition jet size) needs to take that into account.
Aside: Pilot jet = Transition jet, same thing but better description. Mikuni is a Japanese company... Very good carbs but they aren't grand masters of the English language.
I got the correct carb on it now with all the correct parts and have yet to fire it up. I will after I get the new impellers on and everything back together and get a good warm day and stick in the water while still on the the trailer. I live in a neighborhood with our own private boat launch so I will be able to tinker with it and make sure it all works while on the trailer.
The only thing that I'm not sure it the recharge jet is installed in the correct direction. I installed it with the tapered end towards the pump thingy.
Sportster-2001-951C-Stock
Well-Known Member
I think you mean it's a tapered (cone shaped) restricted orifice. I would want the wide end facing down stream so it's not shaped like a basket where trash can collect. ie: I think trash has a better chance of passing through with the wide end oriented facing down stream.
The reality is it probably won't make any difference, though.
The reality is it probably won't make any difference, though.
Update...
looks like the cavitation should be fixed with the driveline rebuild kit and threw on some new Solas impellers. I didn't take it off the trailer but it was sitting in the water and wanted to move the boat as opposed to originally not doing anything.
Now the other issue I can't seem to figure out why it isn't running consistently and smoothly as to this is what I have:
1. Correct carbs that are newly rebuilt
2. I'm not sure what direction the fuel is going so the recharge jets in the small dia. fuel lines are going the correct direction.
3. Fuel is at least 6 months old or as far as I know could be 1 year old and probably no stabilizer was ever used.
4. New sending unit
5. No more Tempo lines and all new fuel and water lines/hoses
6. Choke seemed to work fine as I stated it in the water with air temps at 55 deg.
7. Spark Plugs look normal
8. Oil tank is full with fresh oil
9. Lo fuel adjuster is at 0(no turns out) and Hi adjuster is at 1.5 turns out.
10. For some reason all of sudden there isn't any fuel squirting in the carb from the squirter thingy like the port side when turning the throttle body by hand. This would obviously stop that motor from running which was not doing so well while testing it out in the water. Maybe some blockage or an air leak in that vacuum/pump thingy attached to the carb.
This is what I plan to do this week:
1. Replace the full tank of fuel with new with some type of siphon or pump and do something with a whole lot of fuel, probably distribute most of it between our car and truck as I'm sure they can handle it better than the boat if the octane is low or maybe has some water in it
2. Adjust the Hi and Lo fuel adjusters to Hi being at 0 and the Lo to 1.5 turns out, as I guess I had them backwards(dyslexic of me)
3. Swap the recharge jets 180 deg.
4. Figure out why the heck there isn't any fuel squirting in the carb from the squirter thingy like the port side when turning the throttle body by hand.
Or just drop it off and bend over and take it in the A** because my diagnostic skills are terrible and I'm really frustrated with this :-(
looks like the cavitation should be fixed with the driveline rebuild kit and threw on some new Solas impellers. I didn't take it off the trailer but it was sitting in the water and wanted to move the boat as opposed to originally not doing anything.
Now the other issue I can't seem to figure out why it isn't running consistently and smoothly as to this is what I have:
1. Correct carbs that are newly rebuilt
2. I'm not sure what direction the fuel is going so the recharge jets in the small dia. fuel lines are going the correct direction.
3. Fuel is at least 6 months old or as far as I know could be 1 year old and probably no stabilizer was ever used.
4. New sending unit
5. No more Tempo lines and all new fuel and water lines/hoses
6. Choke seemed to work fine as I stated it in the water with air temps at 55 deg.
7. Spark Plugs look normal
8. Oil tank is full with fresh oil
9. Lo fuel adjuster is at 0(no turns out) and Hi adjuster is at 1.5 turns out.
10. For some reason all of sudden there isn't any fuel squirting in the carb from the squirter thingy like the port side when turning the throttle body by hand. This would obviously stop that motor from running which was not doing so well while testing it out in the water. Maybe some blockage or an air leak in that vacuum/pump thingy attached to the carb.
This is what I plan to do this week:
1. Replace the full tank of fuel with new with some type of siphon or pump and do something with a whole lot of fuel, probably distribute most of it between our car and truck as I'm sure they can handle it better than the boat if the octane is low or maybe has some water in it
2. Adjust the Hi and Lo fuel adjusters to Hi being at 0 and the Lo to 1.5 turns out, as I guess I had them backwards(dyslexic of me)
3. Swap the recharge jets 180 deg.
4. Figure out why the heck there isn't any fuel squirting in the carb from the squirter thingy like the port side when turning the throttle body by hand.
Or just drop it off and bend over and take it in the A** because my diagnostic skills are terrible and I'm really frustrated with this :-(
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Waterluvr
New Member
Your recharge jets work on the venturi principle, the idea being that while they restrict volume they also increase pressure and any vessel that operates as such has a taper, the more open end being on the supply side and the tapered smaller end being on the demand side.
I see you already found your carb settings are wrong so start there, don't get to frustrated if it's not running right these engines and carbs are very simple to dial in just send me a message and if you need to spend some time on the phone I'll talk you through tuning those while it's sitting in the water that's the best place to do it.
Definately get rid of that old fuel that wasn't stabilized, you'll have water in the tank by now if it was ethanol blended gas.
I see you already found your carb settings are wrong so start there, don't get to frustrated if it's not running right these engines and carbs are very simple to dial in just send me a message and if you need to spend some time on the phone I'll talk you through tuning those while it's sitting in the water that's the best place to do it.
Definately get rid of that old fuel that wasn't stabilized, you'll have water in the tank by now if it was ethanol blended gas.
Waterluvr
New Member
Start by getting rid of that old gas, every drop of it. Once there's fresh fuel in the tank use a vacuum pump with recovery cannister and pull a decent amount of fuel from the tank to each line that connects to the fuel pump's and turn the selector valves from on to reserve to purge both of those lines.
Just by doing that you'll know the pumps are getting fuel and we can isolate any issues right to the fuel pump and carb. If you can't pull as far as the pump then your not stuck guessing why the motor won't run or can't be tuned satisfactorily.
Yeah Ill be calling you because I don't know where the vacuum pump, recovery canister, or selector valves are. Here is a pic of how I installed the recharge jet. The video is too large to post.
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Waterluvr
New Member
Read this thread, it's likely you will need to replace the remote fuel pumps that your boat was equipped with I rarely see an original pump that passes testing anymore and they are now obsolete. The Mikuni universal impulse pump discussed in this thread does a great job of replacing them at a reasonable cost and we can discuss testing your's.
http://www.seadooforum.com/showthread.php?63577-fuel-pumps
http://www.seadooforum.com/showthread.php?63577-fuel-pumps
Sportster-2001-951C-Stock
Well-Known Member
Recharge jets? Thought we were discussing return fuel restrictive orifice. If not then strike anything I mentioned above concerning the direction of the orifice, as I'm somewhere else. Assuming these are restrictive orifices in the fuel return, the purpose is to manage fuel pressure and help to purge air from the fuel lines. They do not operate on the Venturi principle, they are simple orifices.
Didn't catch the model of carbs but some have divorced fuel pump while others have integrated fuel pump. I guess yours are divorced fuel pump and once those pumps wear out you'll experience lack of fuel issues. I'd replace these if they're original b/c it's a problem waiting to happen.
Didn't catch the model of carbs but some have divorced fuel pump while others have integrated fuel pump. I guess yours are divorced fuel pump and once those pumps wear out you'll experience lack of fuel issues. I'd replace these if they're original b/c it's a problem waiting to happen.
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Some info from another thread about the recharge jet.
http://www.seadooforum.com/showthread.php?65064-787-carbs&p=354261&viewfull=1#post354261
Post#4 will explain why it's there
http://www.seadooforum.com/showthread.php?60659-99-Challenger-accelerator-pump-question
http://www.seadooforum.com/showthread.php?65064-787-carbs&p=354261&viewfull=1#post354261
Post#4 will explain why it's there
http://www.seadooforum.com/showthread.php?60659-99-Challenger-accelerator-pump-question
Sportster-2001-951C-Stock
Well-Known Member
Correct, the accelerator recharge restrictor is a separate subject completely. My understanding is the accelerator pump supply comes from the fuel metering chamber and not from the fuel pump supply side.
Normally there's a restrictor on the fuel tank return and it's a feature built into the cover of later models. Not exactly sure which models used a separate orifice in the return fuel line.
If the OP is installing the accelerator pump restrictor orifice in the fuel return line that's not going to work well, and vice-versa with the accelerator pump supply line from the metering chamber, if he's using the accelerator pump (not clear on that yet) there has to be some type of restrictor on the accelerator pump inlet to avoid draining fuel too quickly from the metering chamber. Not sure if those restrictors were ever built into the carbs(or acc pump)but I don't think they were. I think the 951 also uses a separate restrictor in the accelerator pump supply as well (I mention the 951 b/c it was one of the last revisions).
Regardless, we're discussing a restricted orifice best I can tell, it's not a venturi and orientation is not going to effect the quantity of fuel that moves through it. b/c it's conically shaped, I prefer to place the cone facing downstream for the reason I gave above but there will be no immediate impact on performance (basically said, it doesn't really matter which direction it's installed aside from it MIGHT pass trash more easily with cone pointing down stream).
And, I would install the a-pump restrictor as intended as opposed to running without it b/c as the throttle is advanced quickly, the draw of fuel volume in the metering chamber as the a-pump is pushing fuel through the acc-nozzles might cause a momentary fuel imbalance leading to a brief lean hesitation once the a-pump shot is consumed.
Normally there's a restrictor on the fuel tank return and it's a feature built into the cover of later models. Not exactly sure which models used a separate orifice in the return fuel line.
If the OP is installing the accelerator pump restrictor orifice in the fuel return line that's not going to work well, and vice-versa with the accelerator pump supply line from the metering chamber, if he's using the accelerator pump (not clear on that yet) there has to be some type of restrictor on the accelerator pump inlet to avoid draining fuel too quickly from the metering chamber. Not sure if those restrictors were ever built into the carbs(or acc pump)but I don't think they were. I think the 951 also uses a separate restrictor in the accelerator pump supply as well (I mention the 951 b/c it was one of the last revisions).
Regardless, we're discussing a restricted orifice best I can tell, it's not a venturi and orientation is not going to effect the quantity of fuel that moves through it. b/c it's conically shaped, I prefer to place the cone facing downstream for the reason I gave above but there will be no immediate impact on performance (basically said, it doesn't really matter which direction it's installed aside from it MIGHT pass trash more easily with cone pointing down stream).
And, I would install the a-pump restrictor as intended as opposed to running without it b/c as the throttle is advanced quickly, the draw of fuel volume in the metering chamber as the a-pump is pushing fuel through the acc-nozzles might cause a momentary fuel imbalance leading to a brief lean hesitation once the a-pump shot is consumed.
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alexd51
New Member
Update...
This is what I plan to do this week:
1. Replace the full tank of fuel with new with some type of siphon or pump and do something with a whole lot of fuel, probably distribute most of it between our car and truck as I'm sure they can handle it better than the boat if the octane is low or maybe has some water in it
I had to clean my fuel tank a couple weeks ago and i tried all sorts of methods to do it ,none worked as good as the $9 Pennzoil pump i got from walmart.
Believe me i tried even with a wet vac with an attachment for chemicals spills and that did not work as well as the hand pump did.
This is what i got from the bottom of my tank.
To be able to reach the bottom of the tank and have the hose go were i wanted it, i attached the hose to a metal wire (The wire used to be a hanger) i did a loop at the end to keep the end rigid and the rest of the hose was attached with zip ties and it worked like a charm.
Here is what it looked like before the zip ties.
If you are going to clean tanks mater as well clean the oil tank also, i took mine out and not only it was dirty as heck with some sort of gelatin kind of oil on the bottom but also the tank was cracked and i would have not known if i didn't take it out .
Good luck.
Not much i can do here i respect every persons choices....LMAO :coolgleam:
Well managed to find some OEM pump replacements, I hope they are OEM style at least
http://www.watercraftsuperstore.net/Mikuni-carburetor-High-Volume-Fuel-Pump.html
I will be getting the hand pump and get all that old fuel out and then work on the oil tank next.
I will also probably taking off the carb and looking at the recharge jet and see if they are clogged.
Waterluv is going to walk me through some stuff also
http://www.watercraftsuperstore.net/Mikuni-carburetor-High-Volume-Fuel-Pump.html
I will be getting the hand pump and get all that old fuel out and then work on the oil tank next.
I will also probably taking off the carb and looking at the recharge jet and see if they are clogged.
Waterluv is going to walk me through some stuff also
Sportster-2001-951C-Stock
Well-Known Member
Yes, the hand pump is a good idea, circulate the fuel back into the tank fill tube as you go and draw the fuel from the bottom of the tanks where the debris are, then through a filter to remove debris. I use something like this sort of the same way a pool vacuum sucks up debris to polish fuel, except I use an electric fuel pump and a fuel filter/water separator on the suction tube at the pump so the pump isn't contaminated with debris.
Primer bulbs are handy for moving small volumes of fuel such as for priming the fuel lines to rid them of air or to start a siphon for draining tanks.
Careful with all of this, gasoline is not only toxic but hazardous as well. No spills or fuel line leaks!!!
Primer bulbs are handy for moving small volumes of fuel such as for priming the fuel lines to rid them of air or to start a siphon for draining tanks.
Careful with all of this, gasoline is not only toxic but hazardous as well. No spills or fuel line leaks!!!
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