rotaxmuscle
New Member
I just had the 787 Rotax motor in my jet boat rebuilt. I got it back, put the mag cover on and installed the engine. To make a long story short - the motor turned over but would only backfire. I indicated the rotary valve and the timing is correct. Come to find out during the rebuild the flywheel was removed from the flywheel hub (the large gear the starter turns) and was not re-installed correctly. It shouldnt have been removed in the first place. I know the flywheel hub needed to be pulled off the crank - but the flywheel itself can be left bolted to the hub when the hub is pulled off the crank. I can pull the mag cover off the motor while its in the boat - I havnt opened it up yet and Im wondering if there is a mark on the flywheel that matches up to the flywheel hub when you bolt it on?? Or do I have to indicate the TDC of one of the pistons and set the flywheel that way?? I have built numerous Rotax snowmobile engines over the years, but all the sled engines have flywheels that are keyed to the crank - so you cannot install them 180 degrees off. What is the easiest way to set the timing and index this flywheel correctly??????
