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Well, here is the problem. I bought a 97 GTX in March that had an SBT engine put in by a shop in Texas, in May of 2000. The previous owner said it has never run right, and he was tired of dumping money into it. The GTX generally doesn't run over 5000 RPM, but on 2 occasions, it suddenly kicks in and runs perfect at 7000 RPM. BTW, I don't have the name of the place that has done the engine swap, or previous work.
The GTX was sold to me with the explanation that it is flakey. I transported it back to California, and did some checking. The results of the first "ride". Engine starts, and at WOT, it runs at about 5000 RPM. The RPM's will also vary, dropping as low as 3500 WOT, and at 1 time, it suddenly cleared and hit about 7000 RPM for about 20 seconds. Motor was very smooth, just before it dropped back down to ~ 5000.
I have another 97 GTX that runs great, and have worked between the 2. To make a long story shorter, here's what I have done, or verified, over about 8 trips to the water.
Raves are clean and are the updated ones with the housing with the additional slots (Thanks, Bryan), fuel baffle circuit board failed (no gauge indication) and was replaced. Fuel line connections and routing have been verified, new fuel line installed between baffle and carb, external fuel filter and internal carb fuel filters have been replaced. Carbs have been cleaned and checked. After doing a little carb work (no problems were found) the carbs were swapped between the GTX's and both sets of carbs run great, on my other GTX (new gaskets each time). New spark plugs. Cut back spark plug cap wires 1/4 inch and reinstalled. MPEM's have been switched (they both work exactly the same in both ski's.)
The GTX experiences several problems. On one checkout, it started and ran at 5000 RPM for 5 minutes, then started to bog down, and back up. After a few more minutes, it started to drop down to 3500 RPM (WOT), and when I crossed over (not jumped) a boat wake, it would lose power, and stutter around 2000 RPM. Finally limped into the marina, where it stalled. Turns over but would not start, and had 2 small backfires. Would also not start on trailer.
Next trip, it started and would do the 5000 RPM number again.
It seems to me that it has to be a timing issue.... either with the Rotary Valve, or timing. First thought was flywheel timing might be off. The old sheared woodruff key and possible movement. Read the Seadoo shop manual, and it shows that there's no woodruff key in the 787 motor, and the trigger pickup is not adjustable. I still feel that it's the timing, and since the problem varies from worse-case (not starting) to best-case (WOT of 7000 RPM for about 45 seconds), I'm trying to track down and nail the little gremlin.
My vacation starts next Sat and I'd love to get this going by then.
Ignition timing, Rotary Valve, ???
SCOTTY
The GTX was sold to me with the explanation that it is flakey. I transported it back to California, and did some checking. The results of the first "ride". Engine starts, and at WOT, it runs at about 5000 RPM. The RPM's will also vary, dropping as low as 3500 WOT, and at 1 time, it suddenly cleared and hit about 7000 RPM for about 20 seconds. Motor was very smooth, just before it dropped back down to ~ 5000.
I have another 97 GTX that runs great, and have worked between the 2. To make a long story shorter, here's what I have done, or verified, over about 8 trips to the water.
Raves are clean and are the updated ones with the housing with the additional slots (Thanks, Bryan), fuel baffle circuit board failed (no gauge indication) and was replaced. Fuel line connections and routing have been verified, new fuel line installed between baffle and carb, external fuel filter and internal carb fuel filters have been replaced. Carbs have been cleaned and checked. After doing a little carb work (no problems were found) the carbs were swapped between the GTX's and both sets of carbs run great, on my other GTX (new gaskets each time). New spark plugs. Cut back spark plug cap wires 1/4 inch and reinstalled. MPEM's have been switched (they both work exactly the same in both ski's.)
The GTX experiences several problems. On one checkout, it started and ran at 5000 RPM for 5 minutes, then started to bog down, and back up. After a few more minutes, it started to drop down to 3500 RPM (WOT), and when I crossed over (not jumped) a boat wake, it would lose power, and stutter around 2000 RPM. Finally limped into the marina, where it stalled. Turns over but would not start, and had 2 small backfires. Would also not start on trailer.
Next trip, it started and would do the 5000 RPM number again.
It seems to me that it has to be a timing issue.... either with the Rotary Valve, or timing. First thought was flywheel timing might be off. The old sheared woodruff key and possible movement. Read the Seadoo shop manual, and it shows that there's no woodruff key in the 787 motor, and the trigger pickup is not adjustable. I still feel that it's the timing, and since the problem varies from worse-case (not starting) to best-case (WOT of 7000 RPM for about 45 seconds), I'm trying to track down and nail the little gremlin.
My vacation starts next Sat and I'd love to get this going by then.
Ignition timing, Rotary Valve, ???
SCOTTY
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