-
This site contains eBay affiliate links for which Sea-Doo Forum may be compensated.
Melting rave valves
- Thread starter onlyadoo
- Start date
- Status
jimmaki
Active Member
Were the rave valves trimmed back, if necessary, for the bore size if it was honed over when they rebuilt the engine?
jimmaki
Active Member
Glad you found it. Lucky you didn't melt more than your RAVE valve.
jimmaki
Active Member
I don't know but if the pipe wasn't getting water things probably got pretty hot on the exhaust side. The mag side would be the closest to the hot pipe. Was the water jacket getting water? The injection water changes the reflected wave timing but it does it by cooling the exhaust temp and changing the temperature density and water content of the gas. I'm not sure how much cooling the reflected fuel charge provides right before the exhaust port closes but I imagine more than none.
Last edited by a moderator:
jimmaki
Active Member
I would imagine it got hot enough to burn the paint and change its color. Assuming it got hot enough to do that you're lucky the raves are the only thing that melted. Good luck! Check for leaks, warped mating surfaces, cracks, etc.
Sportster-2001-951C-Stock
Well-Known Member
Yeah good thing you found the cooling lines crossed, not supposed to get hot enough to burn your hand let alone paint.
Keep an eye on the rubber coupler that joins the tuned pipe to the water box. If that is where the pipe change color you more than likely have damaged that coupling. You'll be riding along and it will get REAL loud all of a sudden and the ski will choke on its own exhaust when it finally goes. If the hose isn't stiff and its floppy like raw bacon, chances are it's cooked. I just replaced one for a guy cause it got too hot.
onlyadoo
New Member
Already had to replace it, but the reversed water lines were totally the problem, the rubber boot also had a hole replaced that and then the spring broke and it stopped revving, replaced that and much better. Only thing left is a fuel issue, not sure if I should start a new thread, but I found fuel in the crankcase. Acts a little rich, hard to tune. Tops out at 52 mph and not quite 6600 rpms, all fuel lines and switch replaced. Carbs have new needles and seats, I rebuilt them but with an aftermarket kit.
Sportster-2001-951C-Stock
Well-Known Member
52 ain't too bad for a 787, eh? Block the fuel return from carbs and pressurize carb fuel in to 10psi (just under pop pressure) and see if it holds without leaking down. Quick dirty test to see if a needle is leaking.
What sportster is asking is for you to leave the carbs on and plug the return line then pump 10 psi of air into the fuel inlet on the carb. You are looking for it to hold the 10 psi for at least a few minutes. This is to see if the needle and seats are leaking. This is typically caused by the aftermarket diaphragms being too stiff and slightly holding the needle and seat open and thus flooding the engine when stopped. You will only know that this is happening if you do the pressure check after the carbs are back together.
onlyadoo
New Member
You know I tested with diaphragm out. So that could definitely be the culprit! I have 3 springs one gives me just under 20 psi, the other gives me 32 that's what were in it, I put them back in, and I have a gold one that gives me 43 psi. 23-43 is what is called for. Also not sure if the arm was flush or not. It smells like gas something horrible when at idle or just above.
Sportster-2001-951C-Stock
Well-Known Member
32 sounds good to me. I think that carb should have the 80 gram spring and 1.5 orifice seat, thus according to mikuni's chart pop should occur near 38psi, which is close. I think 20 is a bit low and will tend towards rich down at low speeds with a lower pop (or leaking needle/seat).
Recently a 787 was brought back into carburetor tune and runs great, see last post of this thread:
http://www.seadooforum.com/showthread.php?78889-Y-all-were-right-I-give-up&p=478276#post478276
1 turn out on the lows.
1/8-1/4 out on the highs. That was hard to judge with the stock airbox in the way. Hah!
Stock spring 80 gr black.
Raves half turn in from flush
all stock jets and needle/seat.
pop off was right between 28-30 on each carb every test.
no leak down
Recently a 787 was brought back into carburetor tune and runs great, see last post of this thread:
http://www.seadooforum.com/showthread.php?78889-Y-all-were-right-I-give-up&p=478276#post478276
1 turn out on the lows.
1/8-1/4 out on the highs. That was hard to judge with the stock airbox in the way. Hah!
Stock spring 80 gr black.
Raves half turn in from flush
all stock jets and needle/seat.
pop off was right between 28-30 on each carb every test.
no leak down
Sportster-2001-951C-Stock
Well-Known Member
I also prefer to test pop with diaphragm removed, and this is the method Mikuni suggests. But if the diaphragm is stiff from age or perhaps of an aftermarket low quality, it's possible the diaphragm might press on the metering lever arm and hold the needle off the seat. Or, there's a chance the needle tip might be damaged, or the seat may have a burr on it, causing the needle to leak and not close properly.
The pop metering is important to be near correct else low speed can be rich if needle leaks, or pop is too low. If the arm is bent down too far this can keep the needle from lifting fully off the seat and cause a lean high speed operation.
So pop needs to be close, and definitely not leaking needle. Everything is calibrated for the air box flow so don't make final judgement unless the airbox is installed and also don't run high speed without the air box or the mixture will be too lean.
Good luck!
onlyadoo
New Member
I also prefer to test pop with diaphragm removed, and this is the method Mikuni suggests. But if the diaphragm is stiff from age or perhaps of an aftermarket low quality, it's possible the diaphragm might press on the metering lever arm and hold the needle off the seat. Or, there's a chance the needle tip might be damaged, or the seat may have a burr on it, causing the needle to leak and not close properly.
The pop metering is important to be near correct else low speed can be rich if needle leaks, or pop is too low. If the arm is bent down too far this can keep the needle from lifting fully off the seat and cause a lean high speed operation.
So pop needs to be close, and definitely not leaking needle. Everything is calibrated for the air box flow so don't make final judgement unless the airbox is installed and also don't run high speed without the air box or the mixture will be too lean.
Good luck!
thanks, tested them leaking there was fuel everywhere in the hull. It seems that every time I touch this thing it cost me money! Anyone want to buy a $3000 raft? LOL. So when I was putting them back together the screw holding the needle and seat broke :facepalm: if isn't one thing it's another!
Sportster-2001-951C-Stock
Well-Known Member
You need to find out where the leaks are and take care of them. It's best to take your time and pressurize the fuel lines with air if necessary while watching for the leaks. A 3ft piece of garden hose to your ear can be used to snoop around and isolate the location.
Hope you were able to remove the screw, I usually lubricate them with oil so the dry threads won't seize. Not sure how Mikuni was able to get them so tight (maybe galvanic corrosion) but they really don't need to be any tighter than just enough they won't come lose and vibrate out, which isn't extremely tight.
Fuel leaks in the bilge are dangerous, I'm sure you're aware.
If it isn't one thing, it's another but it still beats the price of the new skis and who needs to go that fast anyway, my old 720 was plenty fast for me and ran like a top.
Good luck, report back!
Hope you were able to remove the screw, I usually lubricate them with oil so the dry threads won't seize. Not sure how Mikuni was able to get them so tight (maybe galvanic corrosion) but they really don't need to be any tighter than just enough they won't come lose and vibrate out, which isn't extremely tight.
Fuel leaks in the bilge are dangerous, I'm sure you're aware.
If it isn't one thing, it's another but it still beats the price of the new skis and who needs to go that fast anyway, my old 720 was plenty fast for me and ran like a top.
Good luck, report back!
onlyadoo
New Member
You need to find out where the leaks are and take care of them. It's best to take your time and pressurize the fuel lines with air if necessary while watching for the leaks. A 3ft piece of garden hose to your ear can be used to snoop around and isolate the location.
Hope you were able to remove the screw, I usually lubricate them with oil so the dry threads won't seize. Not sure how Mikuni was able to get them so tight (maybe galvanic corrosion) but they really don't need to be any tighter than just enough they won't come lose and vibrate out, which isn't extremely tight.
Fuel leaks in the bilge are dangerous, I'm sure you're aware.
If it isn't one thing, it's another but it still beats the price of the new skis and who needs to go that fast anyway, my old 720 was plenty fast for me and ran like a top.
Good luck, report back!
So the other carbs i had, had Mikuni kits in them had a leak in the pto carb where the filter is, replaced the o-ring with the line through it, ran perfect, $9. I just happen to live 4 houses down from the guy who runs OSD Marine! Have to deal with that screw for my GTX, but at least I'm riding! Thanks for all the help. This ski is in the resto section "gsx from you know where" now just a seat cover and fix the fuel gauge.
Last edited by a moderator:
onlyadoo
New Member
So it ran perfect for a day, still wants to bog on take after idling a no wake zone, after that runs perfect. not super hard to start but have to give it gas, choking is useless. new needles and seats, past leak test. So I'm going to try gold spring see if that doesn't reseat them faster!
- Status
