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spark and timing on a 787 sea-doo

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crundell73

crundell73

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I have a 97 sea-doo 787 that was missing around 3300 rpms and will not want to go over that rpm , will idle just fine and starts really hard .
So I put a test light on it and had a hard time getting the light to work on 1st cylinder , when it did it was innermeten and got no light on 2nd cylinder , now I just had the motor apart to clean out the metal shavings around the stator and trigger , my question is dose it sound like my stator is bad or burnt out , it did have a small burnt smell when I opened the stator plate ?, my timing was advanced about 4-5 degrees .

( also on them jet boats dose any one know if the flush out in the back of the boat is to be closed or open when operating in the water ) Thanks
 
The fitting out the back, by the pump is to be open. Water will flow out there while running.


It could be a spark issue... but hard starting, and won't rev up sounds like a rotary valve that is out of time.
 
Can you post a pic of the engine in question? In your other thread (link below) I know you talked about the timing being advanced. But on a 787 the timing can only be adjusted with a Seadoo programmer or a Candoo, it's digital timing. You can't mechanically change it on a 787. I'm just curious is all, or if someone modded something on you.


But if your engine is a 717 you can mechanically advance the timing thru the stator plate.


http://www.seadooforum.com/showthread.php?80601-sea-doo-will-not-rev-over-3300rpms



Does your stator look like this:

65.jpg






or like this?


160.jpg
 
( It Looks like the first one )
It is a 787 engine I had the plugs out and they fire good when I first turn it over and when I stop and restart it they don't spark until I un hook the dss Key and plug it back on , it is a after market mpem I put in it, I don't know if that is acting the way it should or not .

(I talked to a sea-doo dealer and they said they thought it was the rotary valve also , how would that get off ?)
 
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I am pretty sure you have neutral safety switch. You might want to bypass it. It could be broken since that is the RPM level that it would stop you at. It is made for reverse so you don't blow the gate off the boat. If everything else checks out ok I would look at that. Should be located in the shifter assembly.
 
I think it is already unhooked , you don't thing a 4-5 degree advance on the spark would do that ? I will check into that !
 
Does the aftermarket MPEM have shunt jumpers where you can set the timing? If so, that could be part of the problem. But.......if you put that MPEM on the other engine and it works fine on that engine the MPEM might not be the problem. You need to establish a baseline with your parts.

Sent from my SGH-T889 using Tapatalk
 
Well, how did you set the timing to 4-5 degrees advanced or did it come that way? You have to either switch a dip switch or use a jumper. I just remembered seeing an aftermarket MPEM on Ebay one time and saw it had adjustable timing or it may have been rev limiter, I can't remember. But it just popped into my head. Then I googled for an image of an aftermarket MPEM and saw this (see pic below and read the orange tag),with adjustable timing. But on the back of you engine near the data tag with the serial number on it back by the rear engine mount the case will be stamped with a number 1,2,3,4,5. That is what the timing is set at. I don't recall if that is the exact advance or not, I'd have to go thru a manual to figure it out.




193.jpg








JUMPER


194.jpg
 
ok I will have to look at my mpem to see if it can be done .

So I decided to take my timing light and check the engine that was running good and check the engine that was running bad , on the good one the timing is way advanced but it runs great , the other engine is only 5 degrees advanced and not running good and the good running engine I would say is allot more 25 degrees or so it was jumpy , So I went one more step and checked the mpem and cdi with the not good working engine and got the same 5 degree timing with back fire at 2500 to 3000 rpm . now the book dose not show a key in this engine but is there a key and dose it sound like it sheared to you ? ( Any ideas , I 'am removing the motor as we speak , I have oil leaking out of the one oil injector, why is that ? )
 
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got the engine out not finding much , when the fly wheel hole on the flywheel is at top dead center it is aliened with the cylinder and spark plug hole , is that right or is it to be facing twelve o'clock ? I have to get the flywheel of to see if the key is ok , I did find a gap in the crank case on the mag on the intake side and exhaust side looks to be right at the bearing. good size gap but I 'am not convinced it is leaking air into the case . about 1 inch wide and 3/16 wide .
 
Honestly, looking at the flywheel does nothing for me. Timing is all done off TDC of the Mag piston and specific points on a degree wheel on the rotary shaft. Now, if you had the mag cup off the flywheel and put that on arbitrarily then that could throw off the timing. Seadoo is very specific on the placement of the mag cup. I think I asked you before if you had that off but I can't remember if you said yes or no???
 
Post a pic of what you're referring to. There are a few point that are in the case for prying and separating the case halves, could just be one of those.
 
2015-09-13 21.13.52.jpg this is the hole on the flywheel

This engine is TDC on mag side and this Is where the hole is aliened at dose that look right or should that be at twelve o'clock .
 
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Yep, that's where I was thinking you were looking. That's a separation point.

Sent from my SGH-T889 using Tapatalk
 
Well, there are two pick ups on the mag cup, the trail edge needs to align with that little hole. I find tdc with a gauge, so that hole for tdc to me is nothing, sorry. Read the manual just to be sure in right on the trailing edge. I always refer to the manual when I remove the mag cup.

Sent from my SGH-T889 using Tapatalk
 
in the book it shows the beginning of the trail edge at the hole, but when my piston is tdc the back of the trail edge is a half inch or more past the trigger , going to pull flywheel tomorrow .
 
The key way is straight in line with that little hole in the flywheel. The LEADING edge is in line with that hole, not the trail. The manual doesn't distinguish which end aligns........but they show the lead edge. Just like my pic, which that mag cup had never been separated from the flywheel.



Sent from my SGH-T889 using Tapatalk
 
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