OMC Tech - Help

[PaulO]

Okay another update. Swapping carbs and throttle bodies did not work. So, I have a motor that bogs on acceleration, appears not to have the same power as its twin and I have swapped over all ignition components and all fuel components from good running motor without solving the problem. Only difference I know of is that the "good" motor has compression averaging about 10 psi higher and the "bad" motor is counter-rotating. Although I am down to mechanical issues of the powerhead, I don't know what they could be. Guess I need a new or good used or rebuilt powerhead. Any thoughts are appreciated. Thanks again.

[mrichartz]

Did you ever take the heads off and look a cylinders..
Or do a leak down test?

[PaulO]

Just got off the phone with a local shop/rebuilder. Told me to pull the heads and make sure the sleeves have not rotated. Is this a thing?

[mrichartz]

Yes that's why in the first response I said to take them off
And look at cylinders.
Like I had ,my motor compression was only off a bit but not that much that I excepted what I had ..
started and idled great till I started to take off.

[STV_Keith]

Paul, I see you've swapped all the electronics and intake stuff from one motor to the other, but have you swapped fuel sources? You said they each have their own tank...you're running out of things to swap, but process of elimination works.

[PaulO]

Paul, I see you've swapped all the electronics and intake stuff from one motor to the other, but have you swapped fuel sources? You said they each have their own tank...you're running out of things to swap, but process of elimination works.

Yes ran hose to other side tank/filter etc. Even went as far as to run off of 6 gallon tank and electric fuel pump. Thanks for the idea!

[mrichartz]

You don't have more than one fuel filter to each motor?
Fuel line doesn't have a liner that's all bunched up?

[mrichartz]

Well look at the bright side.. the good thing is you know all the other stuff is good..or so far it's not all the other stuff

But I would bet the cylinder/s that's 15 lbs lower have something going on

[PaulO]

Took the heads off. Here is the summary followed by some pics. All cylinders look nice. No scoring or any marking at all. Ports on sleeves appear to be aligned with block. Used a tiny little round port of some sort to verity alignment and all are perfectly straight although the larger ports seem to vary slightly in their alignment from cylinder to cylinder. Cylinder 2 shows marks in head that looks as though a spark plug electrode had bounced around in that cylinder at one time but there are zero corresponding marks in the cylinder's piston top or the cylinder walls.

[PaulO]

trying to get some pics up But to respond to another post: new fuel lines and yes one spin-on filter per motor although I tried it with the filter bypassed.

[PaulO]

I assume the head damage was from a previous incident and the piston was replaced along with who knows what else. Here is the starboard cyl head.

[H2OPERF]

Sounds like you have been busy... Since its obviously been apart and has never really ran good for you and possibly for last person, can you see where the ring gaps are running in the cylinders?. Possibly one or a whole bank of pistons are in backwards. Throwin darts now lol... just thinkin what may cause issues since you have swaped so many parts. Hate to say it but still seems odd though because you originally said the primer helped makes me think fuel ...

[mrichartz]

Is the low cylinder the one that head is beat up?
And like h2o said can you see if pistons are upside down or scrape them to see markings?
Oh piston looks clean enough are they in right?

[mrichartz]

That looks more like a ring let loose ?
What size is that piston too?

[Instigator]

Previous pop was due to loosing a ring locator pin.

Key being, previous pop.