04-19-2011, 05:43 PM #1
- Join Date
- May 2008
Seadoo 787 huge backfire out of exhaust!!! KABOOMHey guys I just put a new engine in this 97 seadoo xp 787.
I was not the one to build the engine but everything looks to be built correctly with wiseco pistons, new crank, and new gaskets and seals, etc
I try to start it and it backfires through the exhuast and will not start. The backfire is loud and it has done it multiple times. It blew out the rear exhaust hose. Haha my neighbors came over to my shop and thought I got shot or something because it was so loud.
compression is 150 in both cylinders
rv timing is right on the money (I checked it multiple times)
The flywheel key is not sheared
The mag cup is aligned properly with the flywheel.
It has great spark
The carbs are jetted right and clean
The rv cover o-ring is good and brand new
the carb gaskets are good and not leaking air
the crankshaft is not twisted
the pulser coil, the stator and the ignition coil are in spec. resistance wise
the exhaust is not blocked
I unplugged the regulator/rectifier and it still did it
I tried different plugs
could the MPEM cause this? I am out of ideas on what it could be!!!
any ideas what could be wrong? I am kinda stumped
04-19-2011, 07:10 PM #2
your mag cup is off one bolt hole. you need to pull the motor and take the front cover off and see what your timing looks like.
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