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.
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787 bogging and won’t rev over 4K rpm
- Thread starter Kaotic
- Start date
DaddyLoafin
Active Member
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.
DaddyLoafin
Active Member
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
Active Member
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.
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
Active Member
not helping
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 !!
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.
Jtamaro
Member
Spark plugs??
Tim Beasley
New Member
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
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!
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!
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.
I was having similar issues with our 97 XP. Running rough with no power and wouldn't get up to speed. Serviced the RAVEs, inspected/cleaned carbs, (missing 2 bolts on carbs), checked compression (150 on both), checked rotary clearance (in spec), and clipped wires back/new plugs. I went ahead and rebuilt the carbs with Mikuni kits since I was this far down the road. Bought a tach to set idle to spec RPMs. Took it out on lake and started and ran better but still wouldn't get up to speed. I found that I when I ran one of the low speed srcews in I didn't get it all the way in. What I thought was bottomed out was actually debris in the threads or the o-ring causing it to seem like it was all the way in. Also adjusted the injection oil pump to the correct timing marks. Did a little more research here and in the shop manual and decided to check the water regulator valve (If the maximum engine speed can not be attained or if the engine has poor performance, the water flow regulator valve should be considered in the troubleshooting of the problem). There was a rust stain on the side of the waterbox. I took it apart and the spring clamp on the bellows had rusted away to powder. I disassembled the valve, cleaned parts and inspected the bellows for holes. Replaced the rusted spring with a small zip tie. Went back to the lake and what do you know, at full throttle she jumped out on to plane without hesitation and hit 53 mph!!!!! My son came back with a big smile on his face and a thumbs up!
Anyway, I hope you figure it out and this info helps. Keep at it, it took me a month and half to get it running and I was ready to give up and put a FREE TO GOOD HOME sign on it. Also, a big thanks to all the members here that have shared their knowledge. It has been very helpful!!!!
Anyway, I hope you figure it out and this info helps. Keep at it, it took me a month and half to get it running and I was ready to give up and put a FREE TO GOOD HOME sign on it. Also, a big thanks to all the members here that have shared their knowledge. It has been very helpful!!!!
Did you get around to checking the pop off pressure?
