Sea Doo white motor question

[fod]

Just wondering about the white Sea Doo motors. I have been working in a PWC shop for a few months and wwe have had quite a few S-D's in with white motors (all 787 I think) and the majority of them have needed a top end rebuild due to the rear (PTO) cylinder eating it's rings for one reason or another. None of them have had any damage to the front (Mag) cylinder and I was wondering if this is a trend or am I just happening to see a lot of rear S-D cylinders getting fragged? If it is common, any reason for it?

[Bryan Glynn]

I think you are just seeing a rash of similar problems. There are no issues with that happengin specifically.

[Bill O'Neal]

If they are stock motors, remove the internal carb filters and clean them. They get clogged up and the motor eats the piston due to lack of fuel.

[John Kubiak]

Another theory...if you can stand it!!!

The Sea-Doo 787 has a cavity for the balancer shaft drive gears, that is connected to the PTO or rear cylinder via an oiling portfor the PTO end main bearings that is drilled into the crankcases at the transfer port base.

Under SEVERE hydrolock after submerging the engine, this cavity will fill up with water; It is very difficult to clear all of the water out of this cavity in a quick manner.
This is the reason that Sea-Doo added the drain and fill plugs to the balancer gear cavities on the 1997 and later crankcases.

If you can't get all of the water out, you can cause some serious damage to a piston, rod, or bearing in a hurry! Not to mention the balancer shaft gears, and the open bearing at the rear of the balancer shaft

This type of water intrusion is also the main cause of balancer shaft bearings failing due to rust. In fact one of the last symptoms is that the balancer shaft end cap is pushed out of the crankcases; and many people seem to think that the cap was the cause rather than the symptom

[ July 02, 2002, 08:57 PM: Message edited by: John Kubiak ]

[Bill O'Neal]

I agree with John about water getting trapped in the rear CB cavity. I have seen plenty of rusty bearing on CB's in 1995 XP 800 and 1996 782 motors. In 1997, they seperated the CB area from the crankcases, adding an oil filler hole onto the CB cavity.

I also suggest that putting a fuel filter right before the fuel pump in the "on" line that feeds the carbs saves having to be cleaning the internal filters every other year. Just need to change the inline filter every year instead of removing the carbs and cleaning the internal filters......