blown up motor or jumped timing

[hondapapa]

I was idiling up to dock and motor started ratteling then skipping. it cut off,and now it wont turn over,sounds like a dead battery but battery is new. motor is a 1977 johnson 140. I have a shop and do most of my work myself. Dont like to pay some one else. where do i start? can fix most motors,car motorcycle small engines. wher do start?

 

[oldcatamount]

Re: blown up motor or jumped timing

Start with a compression test. When you remove the plugs, take a close look at them. If you find a cylinder (or two) with lower compression than the others by more than 10-15
%, it's probably tear down time. Let's hope that's not the case, but a Service manual would be the best purchase you could make.

 

[emdsapmgr]

Re: blown up motor or jumped timing

If the engine is truly "dead" the small 20 amp engine fuse may have blown. In the main wiring harness, by the starter solenoid. If it cranks, but won't start, the fuse is ok-another problem. If the flywheel key shears, it will get out of time and that will also cause a no-start situation.