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97 Explorer rough idle stalls out

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eggfat

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Hi!, new to the forum and seadoo's. Just got a 1997 Seadoo explorer with a 717 engine. It was running pretty good but idling low at first. took it out a second time and sucked up a rope in the jet. It ran for a little while after and then stalled out and wouldn't start back up. I noticed the engine was a little hot. Brought it back home, I changed the dry black plugs and cleaned out the carb. It fired back up but runs rough at low rpms (vibration) but fine at higher rpms. It will stall out if you let it idle. I was wondering what might be the problem. Would the engine overload offset ignition timing? I fooled around with the low speed adjustment on the carbs and it helped a little to smooth out the low rpms. Would love some advice on what you all think could be the problem. Thanks for your responses. This is a great forum to learn more about these fun machines.:cheers:
 
Hi!, new to the forum and seadoo's. Just got a 1997 Seadoo explorer with a 717 engine. It was running pretty good but idling low at first. took it out a second time and sucked up a rope in the jet. It ran for a little while after and then stalled out and wouldn't start back up. I noticed the engine was a little hot. Brought it back home, I changed the dry black plugs and cleaned out the carb. It fired back up but runs rough at low rpms (vibration) but fine at higher rpms. It will stall out if you let it idle. I was wondering what might be the problem. Would the engine overload offset ignition timing? I fooled around with the low speed adjustment on the carbs and it helped a little to smooth out the low rpms. Would love some advice on what you all think could be the problem. Thanks for your responses. This is a great forum to learn more about these fun machines.:cheers:

Hello and welcome.

Do not adjust idle w/low speed adjustment. It is not recommended.
Put carb needles at factory
High speed is all the way in and low speed is 1.25 turns out for the 717 engine. Or atleast in my case.
Then adjust idle w/screw that opens butterfly in carb. Look down until you can see it open.

Once you can get boat to start and idle out of the water it will not go past 3000k rpm unless you put it in drive.
From there adjust idle higher or lower.
Do not run it on the hose for longer than a few minutes. It's not good for the engine..

Hope this helps getting you in the right direction.
 
Thanks for your suggestion. It has a hard time starting up but will start after a few tries (choke-fires, dies, then release choke and rev high). Some back firing thru the carbs on start. Could this be bad gas? Or should I be taking apart the magneto to check for a sheared woodruff key (from the sucked up rope)? Any other suggestions to get this thing running well again? Thanks
 
The rope wouldn't mess up the timing, but I wouldn't rule out that the key gave up. So... yes, check the timing.

If it was my boat, I would check compression first. (150 is perfect, anything over 135 is OK) Then, raise the idle a little. It should be 1500 rpm's in the water. DO NOT TRY TO ADJUST IT OUT OF THE WATER. (it needs to be loaded)

You shouldn't ever have a true backfire on a SeaDoo engine... but if you did... you will want to pull the carbs apart. You could have burst a diaphragm, ripped the high check valve, or gotten carbon in one of the pilot holes.
 
Thanks for the advice. Checked the compression. 140-150 on one and about 50 on the other. Pretty crushed. Any suggestions on how to proceed and diagnose the bad compression on the cylinder. Noticed that the backfire thru the carbs was thru the bad cylinder. :willy_nilly: Thanks for the advice again.
 
Well.... there's your problem. (sorry)


It's time for a top end rebuild. But... if that engine was never rebuilt... you would be wise to do a full rebuild on it. A company like SBT will be able to get you an engine with a core exchange.

If you are looking for an inexpensive engine... I have one for sale in the classifieds. I don't need a core back, so you could sell your old engine on ebay for a few hundred dollars as a good core.
 
Thanks for your help Doc. I'll look into doing a top end rebuild as a new rebuilt engine was installed a little over 2 years ago. Can I do a top end rebuild without taking the whole block out. I'm guessing if that happens I'll need all new gaskets and re-allignment. The top end rebuild would consist of boring out the cylinders and replacing everything that comes with the kit (pistons, seals, etc.)? Trying to streamline my labor efforts. Thanks for helping out this seadoo newbie.
 
Thanks for your help Doc. I'll look into doing a top end rebuild as a new rebuilt engine was installed a little over 2 years ago. Can I do a top end rebuild without taking the whole block out. I'm guessing if that happens I'll need all new gaskets and re-allignment. The top end rebuild would consist of boring out the cylinders and replacing everything that comes with the kit (pistons, seals, etc.)? Trying to streamline my labor efforts. Thanks for helping out this seadoo newbie.

Not sure on the boring if you got it on time and walls are not scored?? The engine could stay in boat...
Here's the info on top end kit. you have choice of new piston size...


http://www.shopsbt.com/seadoo-jet-ski-topend-kit/60-105.html
 
light scoring

I opened the engine removed the head, cylinders, and pistons. The bad piston exploded in there but the cylinder walls only have one area where scoring is a concern. This is a remanufactured Seadoo 717 engine from SBT. Is there any way for me to know if the cylinders have been previously bored? This way I won't order the wrong size piston kit. The current pistons say "100" on the top of them. Is "100" standard size? Thanks for all your comments
 
Send it back to them :(
You are going to have to do a complete tear down because small pieces may be at the bottom of engine.
Your going to want to fix cause before it happens again with new motor??
 
Thanks ocod, I'm weighing the options of sending it back to them or tearing it apart. It seems that shipping to where I am is outrageous so I might just have to do a cleaning of the bottom and top end rebuild (boring out the cylinders if possible). You know anything about the sizing of the pistons with "100" engraved in it? will it be possible to bore and get oversized pistons?
 
Thanks ocod, I'm weighing the options of sending it back to them or tearing it apart. It seems that shipping to where I am is outrageous so I might just have to do a cleaning of the bottom and top end rebuild (boring out the cylinders if possible). You know anything about the sizing of the pistons with "100" engraved in it? will it be possible to bore and get oversized pistons?

Well, the standard bore on a 717/720 in 82mm. My guess is the 100 on your piston is referring to a 1.00mm oversize (1mm over standard, so an 83mm piston). I would think they should have stamped an 83 in it instead but I never ordered pistons from SBT.

If this is a fresh rebuilt engine in there (didn't read entire thread word for word) you have got to figure why this cylinder went bad or you are going to be doing it again for the next engine you put in. Actually, fresh rebuilt engine or not, you need to look over and confirm your oil injection system and carb(s) (single or double?) is working correctly.

Your cheapest solution, unless SBT will warranty it, is to buy Dr. Honda's ready to go engine, but I think he may be on the verge of selling it to someone. You could rebuild the engine you currently have at your leasure and sell/use when done, or sell it as is as a core for a couple hundred.
 
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