115 Johnson 115 Compression Advice

[barneyfish]

I did a compression check on my J115HP today with the following results:

dry/wet
120/122
120/128
135/140
122/140

I could not start it so should I be worried?

Thanks

 

[Daviet]

Re: 115 Johnson 115 Compression Advice

Should have plenty of compression to start. How is the spark? Will it fire if you squirt some fuel mixture into the carbs?

 

[bigbass87]

Re: 115 Johnson 115 Compression Advice

it seems alright, mine runs 145 135 145 135

 

[barneyfish]

Re: 115 Johnson 115 Compression Advice

Thanks for the quick responses! I did try the fuel mixture shot today with no luck. I also tried to ground the plugs while cranking and didn't get a spark but I don't know if I really had a ground. Should I borrow an inductive light?

Is there a good way to test the stator? I am thinking that if I don't have any spark, it may be rusted over.

 

[emdsapmgr]

Re: 115 Johnson 115 Compression Advice

Not sure just what you mean by wet compression numbers. Adding oil to the cylinders temporarily skews the compression readings and is not a valid number. Compression should vary up to 10% between all cylinders. Typically, a variance of more than that and you could have some issue that should be addressed. You did not mention which compression figures went with which head. Compression can vary between heads-sometimes as much as 5-7 lbs from the factory. What year is the engine? You can do a decarb on the engine and see if the compression come up any afterwards.

 

[barneyfish]

Re: 115 Johnson 115 Compression Advice

The engine is a 94 with little hours on it. Thanks for the decarb recommendation. I will do it once I get it running. I am chasing lack of a spark now.

 

[Chris1956]

Re: 115 Johnson 115 Compression Advice

Disconnect black/yellow wire at the powerpack and see if spark returns. If so, the motor or boat harness, ign key or emergency kill switch (if equipped) is faulty.

 

[emoney]

Re: 115 Johnson 115 Compression Advice

There's a good thread on Spark Test in the sticky at the top of this thread titled, "Top Secret". Lot's of good information contained in that thread, btw. Keep us posted after you follow Chris' advice.

 

[barneyfish]

Re: 115 Johnson 115 Compression Advice

I will follow Chris's advice and keep you posted. Thanks for the terrific advice!