Help! Wife’s coming for me Sea-Doo!

Note: This site contains eBay affiliate links for which SeaDooForum.com may be compensated
Status
Not open for further replies.

Murdoc319

New Member
Long time listener, first time caller- mechanically minded but Sea-Doo experience is limited to this 97 gtx I picked up for what I thought was a good deal in 2017. It ran and I had a great first day- but an oil leak from the return line ruined my life. Couldn’t get it to stop leaking, broke the seal on the exhaust and then had that leak too- wife was fed up and I left for a year courtesy of Uncle Sam.

Fast forward to 2019, we’re moving, wife says the only way I can keep the gtx is if it’s running by Monday. Since I’ve been working on it and it’s sat for 2 years, I’ve replaced all oil lines, oil filter, fuel baffle, fuel lines, fuel filter, fuel selector, exhaust, and rebuilt the carbs with Mikuni kits. She ran yesterday on the hose for a few minutes, adjusted the idle up to 3200 RPMs, things were looking good, until today.

Got her off the trailer into the water, she cranks and idles at 1450 rpms. Start taking a low speed cruise and she sounds a little boggy but it’s relatively ok for low speed. Hesitated at 4K rpm and then jumps to like 6+ and takes off- felt great! Did that again and pulled the lanyard and plugs. PTO plug (1x low speed and 1/4 turn high speed) looks like cocoa and is dry- thought maybe a little rich but ok. Mag (1 turn low speed, 0 turn high speed) looks white! Not chalky it’s just not colored- looks new. Get back to the dock and turn the mag high speed screw to 1/4. Try to get back out, she idles fine and then dies when you try to accelerate. Died at idle on the main fuel line (I may have turned it off?) pitted back to the dock on reserve and put her on the trailer.

Get home and flush her, idles at almost 4K rpm. try turning the low speed screws up to 1.5 turns- carbs were still mounted, didn’t feel like the two carbs were exactly the same, fired her up and idle was now at 1500-2k; figured I might have to reset idle but it was a little rough so I took off the carbs and set them back to 1 turn. Fired her up and BANG, loud noise. Pulled the lanyard. Fired her up again and she sounds fairly smooth but idle is now down to 1500, even with default low speed settings. I’m concerned that I just toasted a cylinder or I’ve got bigger problems.
Of note, I didn’t have a pop off gauge going past 30 so not sure the exact pressure there- tested all of the valves in the carbs. Autozone pressure tester 2 years ago said 120-119 compression- maybe she’s toast anyway but if anyone has any ideas on what I’m doing wrong please let me know! Also of note, ran the regular fuel line on the trailer at home and no issue- don’t think there’s a blockage there.
I appreciate any help or advice!
 
I'd check compression and go from there. You did use genuine OEM kits on the carbs? I'd get a decent gauge setup to check the pop off pressure. On my 97' GTX and 96' GSX, I get about 34-35 psi with the blk 80 gram spring. I've found my skis are happy at 1 turn on the LS needles, and 1/2 on the HS needles. Make sure the carbs are sync'd perfect. Idle at 3k on the trailer should get you 1500 in the water, but I tune for idle in the water.

In the water if you're not getting a bog off idle, I'd leave the LS needles alone. 6700+ RPM on the 97' GTX is good on a WOT run. You may be able to squeeze a little more RPM, but I think a slightly rich setting on the HS is better than a lean setting, like 0 on the HS needles.
 
Thanks GGuillot!
I did use genuine kits, a higher pressure gauge may be worth renting for the pop off- I suspect that may be a problem.

I should’ve mentioned in between the test run that was good and ones that were bad my carb linkage had rattled apart- didn’t do a great job tightening it down. I think I only ran it for a minute before noticing so I don’t think I messed anything up.

At this point I’ve sunk too much money into her to do a top end rebuild so the compression info is just academic. I’m going to assume my low trailer idle at the end of the day and the bang was probably a fouled spark plug and a dead hole backfire. I’m going to trim the plug wires and put new plugs in and see what that gets me. If I have time or if this doesn’t fix it then I’ll go through the pop off pressure- unless that’s something you can do just by sound if there’s fuel in the system while they’re mounted? I know most people do it on the bench with WD-40 which is what I did- just maxed out the gauge at 30 before they popped
 
So put in fresh plugs today and fired her up on the trailer- I didn’t trim the plug wires because they seem fairly snug and it wasn’t obvious how far I should cut. Got a slight misfire/backfire- not nearly as bad as last night, but she fired up and started running- 1500 rpm idle. I think it’s on one cylinder only (pto). Here’s the fun part- I slightly pressed on the throttle and she picked right up and settled to an idle at about 2300 rpm- sounds like the second cylinder started firing but it’s still 1k less than the day before on the same settings.
Any ideas on what else could be wrong? Why it’s firing on one and then 2 cylinders with gas?

Another issue is I’m not sure my oil is injecting at idle- the marks on the pump are lined up but somehow there was half an air bubble and it in one and it wasn’t moving so I freaked out and manually activated the pump to get some oil in the engine- Am I crazy that the bubble should have been moving? Or at idle is the injection rate just that low? Appreciate the help! I’ve been at the beach today so I’m going to go rent a pressure testers and start checking the carbs more in depth
 
At this point I’m hopefully just creating a log of lessons learned- didn’t get to the popoff testing because I turned up the idle screw a half turn and boom she started with both cylinders and above 3k idle- everything seems fine. Turned idle down a quarter to about 3200k, set the oil pump lines and will test her on the water again tomorrow
 
A little trick - If I suspect one plug is on the edge of firing, I pull the wires loose before startup and once she's running I hold each one about 1/8~1/4" off the plug tip and let the spark jump the gap to the plug. This little trick allows ignition voltage to rise up further than if the plug was fouled and will cause a plug that might be fouling or wet to begin firing. If the cylinder comes alive, I put a new plug in that cylinder right away, decision over.

I expect my idle speed on trailer will be slightly more than 2x, ie: 1/2 the speed in water.

But it sounds like it's running, maybe not quite there but it does run so she did say you could keep a running ski, right?

30 pop is probably close enough, I'm wondering if you have a dry carb (clogged low speed circuit). Mix up some pre-mix and give the dry carb a shot of fuel straight down the hatch while idling and see which cylinder picks up, if one does and it comes alive, you just found a dry carb.
 
Another issue is I’m not sure my oil is injecting at idle-

There's practically, no closer to zero or well okay, zero oil while idling. The oil comes in as the throttle is increased, residual oil in crankcase keeps everything lubed while idling so idle long enough there will eventually be no oil. Don't be afraid to fog it, if for no other reason then this one. Just remember, too much oil fouls plugs and makes smoke, that's the only danger.
 
Unfortunately the wife’s terms were running “reliably” without having a legitimate fear of having to use the emergency paddle- just didn’t get there today.

I had company today so I got up at 0630 and put her out on the water by myself- at first she wouldn’t take gas without dying like before but I choked it half a second and she started, no other throttle problems and she was firing on both cylinders at 1450 rpm in the water. No issues accelerating at low speed. There was a brief hesitation from 5-6k on my WOT run but she got up to around 7k.

That’s when the problems started. Pulled the plugs and my mag plug is still virtually white. A tiny bit of color and brown on about half of the thread ring but nothing more- PTO was dark brown again. I only did the WOT for about 10 seconds but I did it twice and didn’t get any other improvement- the carbs are both set to 1 on low speed and 1/4 on high speed- not sure what changes to make next.

To make matters worse, on the way back to the dock the tach died and 12v warning came on, I revved it and it came back on, just to die again, eventually I couldn’t get it to come back on and limped it to the dock. As I ran to get my Jeep I came back and she wouldn’t turn on- pulled her onto the trailer with a rope.

When I got her on the trailer I used the meter and got 12.8v. Not sure what the issue is- when she idles on the trailer she charges the battery to 13.08 or so- haven’t pulled a reading with the ski running, only after it stopped.

Any advice on what carb adjustments to make or what might be wrong with the charging system is welcome- I did replace the rectifier in 2017 when I thought it wasn’t charging my last battery- this ones new and I get positive charging/maintenance on the trailer- just having issues in the water. Thanks again!
 
It would be helpful to know how long you've run the plug(s), they normally start off white and become yellow then settle to moca or cardboard brown. If the plug stays white and the ski doesn't make power, either that plug isn't firing electrically or that carburetor isn't fueling. My bet is the carburetor isn't fueling, it can be a real bear to get the low speed circuit cleaned out in these aluminum Mikunis. You have to remove both the low speed brass jet under the kidney-shaped metering plate and the low speed mixture adjuster screw (I call it the idle mixture screw) and blow the passage through using compressed air (about 80 psi) and some shots of carb cleaner or brake cleaner to get all the junk out.

If that low speed circuit isn't clean, the cylinder won't be getting fuel and yeah, no fuel means the cylinder doesn't fire or intermittently fires and the plug doesn't get coated brown with fuel and oil combustion deposits.

If the plug never or randomly fires due to an ignition problem (even a new plug can be bad), fuel and oil deposits won't be found on the center insulator b/c there was no heat for them to burn. This is possible, just much less likely.

So I'm inclined to say the cylinder with the white plug wasn't firing, or wasn't firing consistently. My suspicion is the carburetor low speed passage is clogged, it's the #1 cause of misfire and lean hesitation.

The high speed circuit has large passages, not much junk tends to collect in these large passages. But, most of your fuel is delivered through the low speed passage unless you constantly ride WOT, which I doubt. And if the low speed passage is clogged, it makes it difficult to reach WOT and if you do manage to reach WOT by nursing the throttle and pulling the choke, it will still be lean at WOT if the low speed circuit isn't contributing.

Running lean causes detonation, which simply means the fuel stops burning prematurely. The reason the fuel stops burning prematurely is b/c there isn't enough fuel to continue burning.

Detonation leads to very high piston temperatures though, the aluminum alloy can be consumed and the piston can expand from the heat beyond safe mechanical tolerance and the excess heat will destroy the oil film leading to a cascade failure. It's like a blow torch on the piston crown, so much heat cannot be absorbed into the cylinder walls.

This is why you must have plenty of fuel, too much fuel (rich) you lose power yes, but there's no chance of roasting a piston, just diluting the oil film, which in excess, isn't good either. "Dancing on the head of a pin" is the old saying in terms of dialing in carburetors.

So if you must fix it now, clean out that low speed circuit in the carburetor of the dry cylinder, make damn sure it's clean then clean it again, poke a wire down through the passage, and into the three pilot holes, get the years of corroded junk out of there. Then clean it once more, shoot carb cleaner through and confirm it erupts from the three pilot holes and passes completely through the passage. Then blow it out with air again, then clean it a few more times, seriously!

Working over an old white bed sheet, you might even see a wad of corroded schmutsa come flying out.

The chances of a bad coil are much less, it does happen though. If single coil you can swap the two wires or dual coil swap the coils and see if the non-firing cylinder comes to life and the good one stops firing by monitoring a new white plug.

I suppose you must be using the correct BR8ES plugs, can't just toss any old plug in these and expect good results.

Take it with you to the new place, there's nothing wrong with it you cant fix. The real concern is if one cylinder loses compression due to a roasted piston caused by detonation.
 
Last edited:
It would be helpful to know how long you've run the plug(s), they normally start off white and become yellow then settle to moca or cardboard brown....

So if you must fix it now, clean out that low speed circuit in the carburetor of the dry cylinder, make damn sure it's clean then clean it again, poke a wire down through the passage, and into the three pilot holes, get the years of corroded junk out of there. Then clean it once more, shoot carb cleaner through and confirm it erupts from the three pilot holes and passes completely through the passage. Then blow it out with air again, then clean it a few more times, seriously!

Working over an old white bed sheet, you might even see a wad of corroded schmutsa come flying out.

Thank you do the thorough explanation- I guess when I was rebuilding the carbs I didn’t really understand where the bypass holes were so I didn’t focus on them- I soaked the carbs for a few hours, sprayed carb cleaner and compressed air through every hole I could find- repainted them and reinstalled everything. I tried looking into the body to see these “3 holes” everyone was talking about but I had no idea if I was spraying the right stuff- looking back I probably was, they were probably just closed up! I was trying to avoid taking the carbs apart again but it looks like I don’t have a choice- I just built them like last week so I’m going to assume re-using the diaphram and fuel filter level gaskets are ok- I’ll replace the fuel pump gaskets with spares from my second rebuild kit.

As for the plugs- I put fresh ones in between tests. So the PTO being mocha and the mag being white to yellow is from a couple minutes of flushing in the driveway, startup at the ramp, a few minutes of idling, and two 10-15 second WOT runs.

Thank you again for the help! I will follow up this week with the results- it’s my anniversary today and the wife will literally murder me if I work on the ski today [emoji23]
 
If a plug isn't firing the plug would be damp at least, backfiring is usually from a lean condition, unburned fuel collects then bam. You're not supposed to poke wire in brass jets and aluminum is softer, if you have to verify use a paint brush bristle, a thin nylon one doesn't bend as easy as organic. Too rich you may foul a plug, too lean and you may seize a piston, you pick which end of the spectrum to troubleshoot/tune, err on the side of safety (rich). I forget how stock carb linkage looks, to check sync back out idle stop screw till it's not touching and a bright small diameter led flashlight, get your face as close as you can focus on the butterflies and slowly move linkage where cable connects and watch the contact area of butterfly that moves upward toward you and make sure they both touch or open at the same time, some of your descriptions sounded like you might have a little lag on 1 carb. And open the hi speed screw up a lot, they meter fuel, damn, I cringe when I see a used white plug. And the hesitation at high rpm may be influenced by your raves sticking or different spring pressure, set the red caps flush with top, service manual or race manual says better to open early than late. And Sportster is correct, they are called low speed screws but they affect the idle air/fuel mixture mostly. You're wife should give you a year for the time you were deployed.... for service to your country I thank you. HUUUAH! Lee
 
Best way to make sure your carbs are clean thoroughly is to dismantle them and throw them in an ultrasonic cleaner. There is no better way to ensure the tiny passages all get cleared out. I was using straight pinesol in mine last year but found it will dissolve the protective coating on the aluminum. I thing the coating is zinc. I bought a cheap harbor freight heated ultrasonic for ~$50. I still use straight pinesol for the brass parts they come out literally looking brand new and shiny.
 
Best way to make sure your carbs are clean thoroughly is to dismantle them and throw them in an ultrasonic cleaner. There is no better way to ensure the tiny passages all get cleared out. I was using straight pinesol in mine last year but found it will dissolve the protective coating on the aluminum. I thing the coating is zinc. I bought a cheap harbor freight heated ultrasonic for ~$50. I still use straight pinesol for the brass parts they come out literally looking brand new and shiny.
ultrasonic cleaners (for me) would break up the solution, but not entirely. There will still be residuel gunk needing to be blown or scrubbed off.
 
Agreed, You can't just throw them in the ultrasonic and wipe them off expecting the goop to all just be gone. Sorry, Should have added that blowing all the passages out and verifying they are clear is still important. I do however find it much more likely that you will be ABLE to clear them out after the ultrasonic.
 
You're not supposed to poke wire in brass jets and aluminum is softer,

I agree if you don't know what you're doing, don't try this at home.

Brass isn't the issue though, it's a fine material for this application. It's the native corrosion of zinc-free aluminum over time that closes the diameter of the precision drilled pilot holes.

This is why so many fail to restore their mikuni ALUMINUM carburetors.

The Achilles heel of the Mikuni alumunum diaphragm carb is the material they chose to cast them from, good enough to get them well past warranty period but to cast them from Zamak alloy (the material of choice for a lasting trouble-free carburetor and even then they apply a chromate pickle/passivation), is a bit more expensive, I'd imagine.

Be careful doing this b/c you don't want to open the pilot holes beyond factory diameter so don't go gorilla on them and you'll be fine. Or, buy new carbs.

One last point, I'd rather be a little fat and perhaps lose 100RPM as a result, as opposed to being lean with little margin for piston roasting detonation.Carburetor wire tool.jpg
 
Last edited:
I agree if you don't know what you're doing, don't try this at home.

Brass isn't the issue though, it's a fine material for this application. It's the native corrosion of zinc-free aluminum over time that closes the diameter of the precision drilled pilot holes.

This is why so many fail to restore their mikuni ALUMINUM carburetors.

The Achilles heel of the Mikuni alumunum diaphragm carb is the material they chose to cast them from, good enough to get them well past warranty period but to cast them from Zamak alloy (the material of choice for a lasting trouble-free carburetor and even then they apply a chromate pickle/passivation), is a bit more expensive, I'd imagine.

Be careful doing this b/c you don't want to open the pilot holes beyond factory diameter so don't go gorilla on them and you'll be fine. Or, buy new carbs.View attachment 40976
Is this why people have had so much trouble with my carbs? Everything imaginable had fused itself to the carb and everything had been corroded.
 
Yes, this is my opinion. We're dancing on the head of a pin.

How long should a carburetor last in years, is this planed obsolescence or just a cost cutting strategy to maintain profitability?

I'm sure everyone has observed the powdery-white ceramic corrosion that tends to grow on the surface of low cost aluminum alloys over time. Look closer if you will, the layer of surface corrosion is considerably thicker than the original dimension, like a spongy layer of AlO2 has grown. Consider, quality carburetors are rarely made of aluminum due to it's instability and it's commonly accepted that brass is the material of preference for machining the precision orifices in about all carburetors, even the cheapest of phenolic resin and plastic body carburetors the critical orifices are typically brass.

Given these fine orifices are precision drilled into a chemically unstable aluminum substrate (orifice diameter is relevant, yes?), why should we anticipate the orifice will maintain within serviceable tolerance beyond a decade or more? As the native oxides grow on the aluminum surfaces over time, the orifice diameter will decrease, resulting in a restricted orifice.

Does shooting some solvent like brake clean or carburetor cleaner (otherwise known as acetone) through the orifice remove the spongy aluminum oxide layer? I argue it will not, but it will only dislodge sticky fuel gum deposits and wash away loose debris one might ordinarily find in any orifice, such as brass. In severe cases, it's even necessary to "rod out" a brass orifice, which is probably 100x less susceptible to substantial corrosion than aluminum.

Of course aluminum oxide growth can be etched back using chemical means, such as an acid dip or reopened to approximate the original diameter using mechanical means, but doing nothing to reverse the restricted orifice diameter while expecting improvement (this is the definition of insanity?) often results in a leaner than factory air/fuel mixture (lean hesitation is a primary symptom).

Can you see the difference between a 80 orifice and a 75 orifice by eye? Perhaps side by side but I certainly cannot by peering from an angle down into the throat of a carburetor. These dimensions BTW, represent a difference of 2 standard jet sizes, and will make a considerable difference. Now divide the difference by 3 pilot holes, and remember according to Poiseuille's law, the flow rate through a length of pipe varies with the fourth power of the radius of the pipe

I cannot count the instances of reports "I cleaned those pilot holes thoroughly with carb cleaner, what next?" where the end result was still hesitation.
 
Last edited:
Update!

Usually when I think something is wrong I’m usually 100% convinced the problem is completely the opposite of what it actually is...

That said, I’ve been reporting plug coloring based on the insulator tip and less about the covering on the last metal ring on the plug. When I run on the hose at idle my insulators are typically white with some wet fuel on the metal ring. I do have a little premix (1/4 tank) left and filled the rest of the tank with fresh gas and seafoam so I expect it to be running a little rich.

After running on the water at mid range then WOT I’ve been pulling the plugs and even after a few minutes the PTO plug is covered in carbon- both the ring and insulator tip and the MAG plug has had a white/slightly tan insulator with about half of the metal ring covered in brown dust.

I thought I had a MAG problem so I took apart that carb again- plenty of fuel on both sides of the fuel pump. I sprayed cleaner with the check valve tip on the cleaner stick and may have had blockage but eventually saw cleaner coming out of the venturi hole and the three small low speed holes. I was looking down and didn’t know about the larger hole under the Venturi so not sure if that’s clear. Ordered another rebuild kit but not sure that’s necessary yet.

Anyway- put her on the water and got more bogging mid range - expected from residual premix- but smoother acceleration- a little bit of a bump to wide open throttle but much better than before. She surged up to 7.5k rpms but settled at 6.5k rpm at WOT The rest of the trip. Pulled the plugs twice and think the MAG plug is getting a little bit of color on the insulator tip and a decent amount of color on the last metal ring. The PTO plug is getting covered in carbon still.

I’ll take pictures of the plugs later- I had reused the old ones yesterday for the MAG but put a non fouled plug in for the PTO so I think the carbon buildup is still the issue.

Without the pictures- do y’all think I have more of a PTO problem than a MAG? Both high speed screws are set to 1/4 turn and both low to 1 full turn. Is the residual premix enough to cause this carbon build up? The wife is making me unload the ski and I’ve got a lot of offers but I’d like to make sure it’s running right before I let her go and for my own experience before we pick up another machine down the road.

Also- got a little oil in the hull. The return line was leaking from a work clamp when I got it. I put an oetiker ear clamp on before I put the exhaust back on but I don’t think it sealed all the way- it’s really hard to get pliers in there. Is there anyway to lift the engine without damaging the drive shaft or realigning to get to the hose? If I take the pipe off without breaking the clamp seal there’s just not enough room. I may take off the reverse linkage to gain some space. Otherwise I’ll just warn the buyer but I don’t want to leave them with a leak if I can avoid it. I appreciate all the help thus far- y’all have been great!
 
If you're getting 6500 RPM in the water, there should be some decent speed with that or there's something amiss with the jet pump, etc. If you;re getting speed as well, I'd say both cylinders are making power. The mixture needles are for fine tuning if needed, however, factory position should produce acceptable results else there's probably an issue.

If you loosen the engine mounts, it should be realigned.

Last metal ring on the plug is of no significance to me, FWIW.

I'd be more concerned with hesitation and loss of power, these are two big no-no's in general, especially concerning for 2-strokes.

It's not nice to have oil leaks, some tanks have a seam crack where they leak. A dry clean paper towel lying underneath can reveal leak points assuming the oil isn't traveling on the outside of the tube before it drips off.
 
Last edited:
On my 97' GTX, this weekend I was seeing a slight tick over 6700 at WOT. Carbs set at 1 turn on the LS and 1/4 on the HS.

You're there at 6500. Ck your water valve on top the muffler, that can shave a couple hundred rpms on the top end. Mid range below 5k sputtering a little bit is normal on the 787.
 
If you're getting 6500 RPM

Thanks sportster!

I do have speed at 6.5k RPMs; just trying to figure out the disparity in my spark plug color with one being carbon fouled and the other barely coloring, even after another clean out.
I’m wondering if I should turn down the HS screw back to 0; someone else claimed it was 0 on the mag and 1/4 turn on the PTO for the 97 gtx but the manual doesn’t seem to have any input on the HS, just the low speed screw. That said, if both carbs are the same I should be getting the same results and I’m not- solutions to one carb would cause problems to the other if I match settings . I’m probably going to clean the mag one more time- I just don’t want to do it without another diaphragm on hand- when I took the one I installed last week out, it was swollen and warped- which has me somewhat concerned for only a few minutes of operation; had to put the old genuine one back in because it was in better shape.

I don’t think I have an oil tank leak but at this point I don’t know- I saw a black dot of oil at the return line fitting even though the hose looks sealed with my bore scope. I still think that’s the culprit- probably time for the paper towels.
 
On my 97' GTX, this weekend I was seeing a slight tick over 6700 at WOT. Carbs set at 1 turn on the LS and 1/4 on the HS.

You're there at 6500. Ck your water valve on top the muffler, that can shave a couple hundred rpms on the top end. Mid range below 5k sputtering a little bit is normal on the 787.

This concerned me, it's normal?

"Anyway- put her on the water and got more bogging mid range - expected from residual premix- but smoother acceleration- a little bit of a bump to wide open throttle but much better than before. "
 
Thanks sportster!

I do have speed at 6.5k RPMs; just trying to figure out the disparity in my spark plug color with one being carbon fouled and the other barely coloring, even after another clean out.

Speed is encouraging news. The plug color won't stabilize within minutes, after 30 minutes you might have an inkling. To really nail plug color, a WOT blast chop power is the method.

But to me, this has less meaning than lean hesitation, which isn't to be confused with rich 4-stroking (opposite sides of the dance floor).

The plugs start with white, become yellow then become mocha brown and normally settle to look like this after several hours.951 plugs2.JPG
 
This concerned me, it's normal?

"Anyway- put her on the water and got more bogging mid range - expected from residual premix- but smoother acceleration- a little bit of a bump to wide open throttle but much better than before. "

It concerned me a little too; I don’t think it’s of much note but I’ve been running with just the flame arrestor on and not the airbox- maybe that will help a little with the PTO carb but it’s probably going to make things worse for the MAG.

I also don’t use choke at all to start... and I have a crappy gasket on the MAG carb- have thicker ones coming in the mail today so I’ll slap one of the oem ones on..

Everything’s trying to tell me SOMETHING. What is it???
 
Status
Not open for further replies.
Back
Top