is the is compression range acceptable

[yammyman]

I have the option to purchase a 1996 115 Johnson. The guy that has it says the compression is between 105 and 120 across all 4 cylinders. Should I be concerned that at least one cylinder is at 105?

 

[masterbt]

shop manual 15psi between two cylinders not good test to determine cause. rings or scored cyl.

 

[yammyman]

Thank You sir!!!

 

[boobie]

You're right on the line. Try a good de-carb first , then recheck it before taking it apart.

 

[emdsapmgr]

I always consider 10% variance between high and low cyls a normal difference. Yours is just under "normal" so it's questionable. Probably want to pull a head and do a visual inspection on the low cyl. It's normal to have up to a 5 lb difference between the two heads, due to the way the blocks are manufactured. Agree, a decarb wouldn't hurt anything and may get the compression back up into the "normal" variance range.

 

[itsaboattime]

I would be concerned. And here's why.
Yes a decarb would probably go a long way toward raising the compression, however, is the seller going to let you do it before he sells it to you? And if he won't, what happens if you buy it and do the decarb and it doesn't help very much, if any? Or after you do the decarb and it doesn't help, you pull the head and find a scored cylinder?
If I were you, I'd do my own compression test and find out which cylinders are low. You may have 3 out of 4 around 105.
I don't know about all of them, but my local Autozone will rent out a borescope. I would check out those low cylinders and see if you can see what's going on in there.

 

[yammyman]

I decided to stay away from it. I have a 130 yamaha with a bad lower unit. I ran across a good deal on a slightly used unit.

Thank you all for the advice.