74 Johnson 25 hp woodruf key replacement

[clarifydeveloper]

I have a 1974 25hp Johnson longshaft with power pac that was running strong for several years. One day about 2 years ago i was heading upstream with a heavy load in the boat and suddenly the engine died. After getting it home it would only backfire and sputter when attempting to crank. I posted here at that time and was directed to remove the flywheel and inspect the key.

well, i finally got the flywheel off tonight and the key is still in the slot on the crank, the flywheel doesnt appear damaged. The key is sorta pressed in the slot and i havent tried too hard to get it out yet. It isnt broken, just sorta "smoothed" looking, like maybe it slipped just a little but didnt spin around and round.

anyway, once i get it out and put a new one in, whats the torque for the flywheel nut? any other tips on making sure i do the job right?

tight lines

 

[clarifydeveloper]

Re: 74 Johnson 25 hp woodruf key replacement

oops, its 77

 

[clarifydeveloper]

Re: 74 Johnson 25 hp woodruf key replacement

I really need some help. The flywheel had not spun, I put a new one in, torqued the nut to 45 lbs and it just backfires when i try to start it. My old thread was http://forums.iboats.com/showthread.php?t=280176 and all the details are there. I didnt add on to that cause its so old.

Please help

 

[milliesdad]

Re: 74 Johnson 25 hp woodruf key replacement

Points gapped? Compression tested?

 

[mstahl1171]

Re: 74 Johnson 25 hp woodruf key replacement

Checks points and compression as milliesdad says. Are you sure you have good hot spark?? Have the carb been cleaned and rebuilt? Float valve not stuck or gunk in bowl??

 

[wilde1j]

Re: 74 Johnson 25 hp woodruf key replacement

Backfire is usually caused by timing whacked (sheared key). You sure the new key hasn't sheared? BTW, was it a BRP part or a hardware store key? The only proper key is a BRP part, BC the hw staore variety aren't hard enough. BTW, you only get a few tries before the crankshaft and flywheel become junk.

 

[clarifydeveloper]

Re: 74 Johnson 25 hp woodruf key replacement

i ordered new keys from online marine parts store. The engine has a power pack, no points. Spark is good. It sounds like its out of time but there is no adjustment as I understand its the key alignment that sets the timing.. Why are there timing degrees stamped in the flywheel?

It will almost start when cranking then an earth shattering kaboom backfire, then almost start and kaboom. This engine has always been quick to start and run very well, it was running at 3/4 or so throttle with no sign of any issue when it died, it was if the key had been turned off. This leads me to believe carb is ok, but thats the next step i guess

 

[AlTn]

Re: 74 Johnson 25 hp woodruf key replacement

it may be telling when you state, "....it was if the key had been turned off.". Have you tried unplugging the black/yellow wire from the powerpack and hand cranking it? If there's a plug you can pull to eliminate the wiring from the key switch, try unplugging it to start. This will take the switch out of the equation.