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mid-70s? 6hp Johnson no spark bottom cyl. -- where to start?

K

kippstakes

Member
I am working on a 6hp Johnson for a bud and right off the bat it has no spark on cyl 2 when pulled. I am used to working on larger, electric-start models. Where should I start here?
Thank you
 
6rL-72d, so I'm guessing 1972 then. I am using an open-air gap tester. Spark is white and strong on number one, but number two's giving me nothing.
 
Even if only one coil is cracked change all three coils, points and condensers. If there is any slop up and down on the armature plate under the flywheel replace the mount and ring while you have the flywheel off. Another common wear item is the head gasket. If the compression is even but low pull the head and inspect the cylinders before deciding on spending much money on the motor. The motor is 43 years old if the cylinder walls are glazed over a quick hone and new rings and theoretically you can get another 40 years.
 
kimcrwbr1 said:
Even if only one coil is cracked change all three coils, points and condensers. If there is any slop up and down on the armature plate under the flywheel replace the mount and ring while you have the flywheel off. Another common wear item is the head gasket. If the compression is even but low pull the head and inspect the cylinders before deciding on spending much money on the motor. The motor is 43 years old if the cylinder walls are glazed over a quick hone and new rings and theoretically you can get another 40 years.
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Sure, compression was a bit on the low side also. 75/65, so not great but I think w/in the serviceable limit. I might just tell this dude to try and get his money back, this thing seems like a can o worms. I'll see if I can get the flywheel off tomorrow.
Thank you
 
Get three grade 8 1/4-20 bolts three inches long and use a harmonic balancer puller. The flywheel can be preety tight just crank on the puller until you think the bolts will break then lift up hard on the puller and smack the ram with a hammer. Be sure and screw the bolts in at least 5 threads and pull up hard so you dont damage the crank bearings when you smack the puller. Anything around 70 and even will run just fine you a little over 10% between cylinders but could be how you tested it. I allways test the compression engine cold and test it three times. 1-2 1-2 1-2 that eliminates any mistest just use the high number for each cylinder. Ignition parts are cheap if the gearbox is holding pressure and not spewing metal shavings get a good spark rebuild the carb and fuel pump, replace the fuel lines and impeller and run it till it pukes.
 
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