One little thing is missing. After installing the belt I would recommend rotating the crankshaft manually two revoloutions in order to make sure the pistons will not hit the valves when firing up the first time. John, your videos are actually the best outboard how-to-videos out there. Very good explanation, but also very good audio quality, pronunciation and talking speed. Makes it easy to follow even for non-native English speakers.
As someone who's been a professional mechanic for a very long time and has seen many broken timing belts I can tell you that you cannot inspect a timing belt to see if it's going to break or not. I've seen timing belts that looked brand new break and I've seen timing belts that look like they should have broken years ago still working fine.
Great video. I usually turn the motor a couple of times in the correct rotation by hand to ensure marks are 100% lined up.. What holds the flywheel is a nut not a bolt,in my neck of the woods...
Good video John. My 25 Yamaha 4 stroke stopped and won't restart.The compression on both cylinders is only 75# and the timing belt is very loose.Could it have jumped time or is it something more serious. Thanks
If your engine was running when it "jumped time" then the crankshaft and the camshaft became out of phase/time at some point. John mentions this issue in passing during this video. When the crank and camshaft are not synchronized (out of time/phase) the valve(s) are likely to be still in the open position when the piston comes up to top dead center at some point. This is a problem because if yours is an "interference" engine meaning there is NOT enough room in the top of the piston chamber for both the piston and the valve(s) being in the open position to happen at the same time-one or the other but not both at the same time, then impact and damage occur. Damage happens when the piston(s) hits the valve(s) damaging/destroying the valve, piston and possibly the piston chamber. With that low of a compression this may have occurred. You could do a "leak down" test to determine where the leakage is occurring; one or both valves, the head or someplace else, but that requires some more equipment. Hope it helps-
