787 bogging and won’t rev over 4K rpm

[Kaotic]

I have a 1997 gtx with the 787. When I bought it he said it would bog and not get on plane and said he was told the carbs need rebuilt. He had the rebuild kits however I don’t think they are oem kits. So the first day I put it on the water just to see exactly what he was talking about. Sure enough it was bogging and would only get to about 4K rpm and then bog out and die. Restart and would be bogging then the rpm would shoot up to 4 some times 5k rpm then bog and die instantly. So I took the carbs apart and everything looked ok. Screens were clean and so were the jets. I went ahead and rebuilt them with the kits he supplied and it still does the same thing. I did not check pop off however because I didn’t have a gauge built but and building one tomorrow. I’m also ordering new OSD kits tomorrow as well. I have cleaned and rebuilt the rave valves as well. What else could cause the issue? I did notice today that I was leaking water from the upper exhaust pipe so evidently there is a crack or something up there so could that be causing part of this? Just trying to get some other ideas to check while waiting on the new carb kits to get here. Thanks for any help and sorry for such a long post.

 

[DaddyLoafin]

I have a 1997 gtx with the 787. When I bought it he said it would bog and not get on plane and said he was told the carbs need rebuilt. He had the rebuild kits however I don’t think they are oem kits. So the first day I put it on the water just to see exactly what he was talking about. Sure enough it was bogging and would only get to about 4K rpm and then bog out and die. Restart and would be bogging then the rpm would shoot up to 4 some times 5k rpm then bog and die instantly. So I took the carbs apart and everything looked ok. Screens were clean and so were the jets. I went ahead and rebuilt them with the kits he supplied and it still does the same thing. I did not check pop off however because I didn’t have a gauge built but and building one tomorrow. I’m also ordering new OSD kits tomorrow as well. I have cleaned and rebuilt the rave valves as well. What else could cause the issue? I did notice today that I was leaking water from the upper exhaust pipe so evidently there is a crack or something up there so could that be causing part of this? Just trying to get some other ideas to check while waiting on the new carb kits to get here. Thanks for any help and sorry for such a long post.

The gasket from the exhaust manifold to the tuned pipe could be leaking water. And if its leaking exhaust fumes as well as water than it could just be starving for O2. Make sure its not leaking fuel from any on the lines on the carbs as well.

but it's also incredible common for the welch plus on that pipe to rot out from the inside and spray water.

 

[Kaotic]

So I did pull the upper exhaust pipe off and there is a pin hole in one of those plugs. Can these be welded or are they junk and you have to find a used one? I was looking last night and couldn’t find a place that had new ones.

 

[DaddyLoafin]

So I did pull the upper exhaust pipe off and there is a pin hole in one of those plugs. Can these be welded or are they junk and you have to find a used one? I was looking last night and couldn’t find a place that had new ones.

yeah, they have to be tig welded.
you can do what I did and take a gamble on ebay and you might get lucky and get one for cheaper than it'd cost having someone weld it for you. But I was lucky the one I bought had already been welded.

 

[Rabid]

yeah, they have to be tig welded.
you can do what I did and take a gamble on ebay and you might get lucky and get one for cheaper than it'd cost having someone weld it for you. But I was lucky the one I bought had already been welded.

Some on this site have used JB weld to fix until they get a chance to pull and weld. I just found one myself. Im going to jb weld until I get some time to pull and find a welder.

 

[Kaotic]

A buddy of mine owns a welding and fabrication shop. I took it to him and he said it won’t be a problem to weld up.

 

[Kaotic]

How many fuel filters should be on this machine? I ask because there isn’t a filter in the separator bowl, then about 6 inches from it they have an inline fuel filter and then about a foot from the carbs they have another inline filter. I was told all there should be is just the separator bowl because they weren’t designed to suck through a paper filter let alone 2 and that may be part of my problem.

 

[DaddyLoafin]

How many fuel filters should be on this machine? I ask because there isn’t a filter in the separator bowl, then about 6 inches from it they have an inline fuel filter and then about a foot from the carbs they have another inline filter. I was told all there should be is just the separator bowl because they weren’t designed to suck through a paper filter let alone 2 and that may be part of my problem.

not helping

 

[etemplet]

How many fuel filters should be on this machine? I ask because there isn’t a filter in the separator bowl, then about 6 inches from it they have an inline fuel filter and then about a foot from the carbs they have another inline filter. I was told all there should be is just the separator bowl because they weren’t designed to suck through a paper filter let alone 2 and that may be part of my problem.

There is likely your problem. Get rid of both inline filters and install the separator filter. The fuel pumps do not like inline filters for some reason. I never do this but you can try running and unflitered line direction from the fuel tank to the carbs as a test..

I can tell you from experience, I put an inline filter on my 1996 587 SPI (first ski) and it ran great for about an hour then got worse and worse. I checked and checked everything. I was told my @mikidymac to remove the inline filter and viola... no more issues at all.... evah. Ditch the filters and go back to 100% stock. Good Luck !!

 

[Kaotic]

I removed both filters and changed the line, put in a screen in the bowl because there wasn’t one, redid the race valves again to be sure, drained all the gas and put new in, put in new spark plugs, and rebuilt the carbs with an osd kit and fixed the hole in the plug on the exhaust pipe. IF it doesn’t run now where should I go? Electrical? I’m going to try to take it out tomorrow but if not for sure on Friday so we will see.

 

[etemplet]

Patience, let it come to you. You made a lot of good changes. If you did it all correctly you shouldn't have fuel issues. Good Luck !!

 

[vogs77]

Don't forget to check you charging system, my 96 GSX was overcharging and would not run correctly. New used regulator fixed it all up, don't use an aftermarket one.

 

[Kaotic]

Took it out today and at full throttle in the water it stays at 3500 rpm. Won’t go over but it also doesn’t bog down and die now. Out of the water it revs just fine. What am I missing?

 

[Kaotic]

I think I may have figured it out. I have 1 plug wire not firing but on occasion the other one is fine because I can switch cylinders and it will work. Compression is good on both cylinders.

 

[JJinSC]

Make sure you are running the correct spark plugs too. If you do not know the age of the existing ones replace them.

 

[jemery.wa]

Spark plugs need to be replaced a lot on these machines I have found. Also you can pull the boots off and cut a little off of the wires and re-install the boots to get rid of any corrosion that may be causing problems with spark.

 

[Kaotic]

I put new plugs in BR8ES which is what it called for and also cut the wire back. I could still move that wire to the other cylinder and it wouldn’t fire but could move the back wire to the front and make the front cylinder fire so I’m thinking it’s a bad wire from the coil.

 

[mikidymac]

Your ski fires both plugs at the same time, it’s a wasted spark system. So if only one is firing it sure sounds like a bad wire or connection.

 

[Jtamaro]

I have a 1997 gtx with the 787. When I bought it he said it would bog and not get on plane and said he was told the carbs need rebuilt. He had the rebuild kits however I don’t think they are oem kits. So the first day I put it on the water just to see exactly what he was talking about. Sure enough it was bogging and would only get to about 4K rpm and then bog out and die. Restart and would be bogging then the rpm would shoot up to 4 some times 5k rpm then bog and die instantly. So I took the carbs apart and everything looked ok. Screens were clean and so were the jets. I went ahead and rebuilt them with the kits he supplied and it still does the same thing. I did not check pop off however because I didn’t have a gauge built but and building one tomorrow. I’m also ordering new OSD kits tomorrow as well. I have cleaned and rebuilt the rave valves as well. What else could cause the issue? I did notice today that I was leaking water from the upper exhaust pipe so evidently there is a crack or something up there so could that be causing part of this? Just trying to get some other ideas to check while waiting on the new carb kits to get here. Thanks for any help and sorry for such a long post.

Spark plugs??

 

[Tim Beasley]

Check the clearance in your rotary valve about 0.012 is a good number I had one that would run great out the water but just as soon as it hit the water it would bog down and stall start right back up fine and something over again

 

[seadoosnipe]

All the help, that’s awesome! After reading through everything, I’m going to add a couple things. I have a 97 GTX, and I’ve experienced this before. For my issue, it was the rave valves. The red plug is to adjust spring tension. It should be flush with the black cap. Also, the internal porting that comes up through the valve, is small. Make sure they are clear, and the gasket internal porting is on correctly. It can be put on to block the 1/8” hole from the head, if not attentative. Make sure the exhaust bellows isn’t cracked or leaking. Last, the guillotine slides are very finicky. Make sure no carbon deposits interfere with smooth operation.

One other thing, I didn’t see any mention of compression. Why I mention this is due to it running great, when out of water, no torque on motor. If compression is low, and you put a load on it, with low compression, it can have almost the same effect. I would def check it, make sure it’s above 100 (no lower than 90-95) and both cylinders are within a few pounds of each other.

You got a lot of great replies! I’m sure someone has probably got you in the right direction!

 

[Kaotic]

earlier this week I changed the coil. Today I was finally able to make it to the lake as it’s an hour from my house. At first it would spit and sputter while in the trailer in the water. I'm not sure why but I am hoping it was due to bad gas. When I bought the thing it had a full tank but not sure how long it has been in there so I drained most of it out. There may have been a gallon or so left and in the lines. Then when I took it out last weekend it would only hit on 1 plug wire. I could move it to each cylinder and that one would fire but the other wouldn’t on either cylinder so I changed it this week. So like I said it would spit and sputter in the water on the trailer. After a few minutes it picked right up and so I took it out for a while and it ran pretty good. The only thing I don’t fully understand is why I will be at full throttle when I take off or I can be cruising at half throttle and then punch it but only go to 5500 rpm or so. Then after about 5-10 seconds it will jump to 6900 and hit the powerband. Could it be the raves? I currently have the ones on the engine backed out flush but just read a post that said 97 should be all the way in. Compression is between 135-140 on both cylinders.

 

[JJinSC]

Turning the red caps one the RAVEs in increases the spring tension and would make them open later. Leave them flush. The symptoms you describe could be several things. The first and easiest to eliminate is inspect/clean the RAVEs.