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1975's First Carb Cleaning

tboltmike

Regular Contributor
My 115 has been in the family since new and I have had it since '88.

A few weeks ago it lost power on #2. Good spark and the compression varied 12 psi high to low. Next most most simple thing to do was open the carbs. But before that, I opened the plugs at the high speed orifices and blew low pressure air thru. Fired it up again and #2 still dead.

When I opened the carbs, the bowls were near pristine. No debris or varnish, valve seats looked good, the floats were still properly set, no visual clues of jet clogs and air passed thru all passages, even the gaskets broke free with no damage. There was no gunk observed blowing out.

I have two fuel filters, a simple in-line followed by a spin on with separator bowl. Early on, I used the 4+2. About 5 years ago did Sea Foam shock treatment and as an additive. The last year or so, been using the PRG. After each use, while running on the hose, I disconnect the fuel hose. When it starts to start to increase idle speed, I chock it to death. That is what is nice about having a chock and mixed fuel in that a rich fuel mix leaves a good coating of oil in the system.

Shot some carb cleaner thru the passages followed by air. I didn't do a kit and reused everything. It was Sunday and the OMC dealer didn't open 'til Tues. I was anxious to get it together and see if this changed anything.

Got 'er set up, raised the fast idle lever 1/4 up, engaged the choke, turned the key. Fired in about 5 revs and nearly jumped off the boat, figurativily speaking. All cylinders were hitting.

Apparently something was wrong with the fuel to #2, but I couldn't see any positive reason. All I know is that running and apparently very well. Debating to go back in the carbs and install the kits. Maybe next year.
 
It might have been some 'dissolved' parts from a fuel line that is starting to deteriorate that have blocked a jet.
replace all old fuel lines with new!!
 
I would go one step further. Carb kits and fuel pump as well. Yes it is time and money, but ...new engine would cost a lot more.
 
I noticed that the fuel lines to the carbs had 1975 dates stamped on it. My plan was to identify if the carbs were the problem. Did't want to invest a lot if the problem presisted. Now that I know it was the carbs and now that I have muscle memory on removal technique, I plan on doing as you say.

However, the only critical thing I see in the carbs' reliability are the gaskets for the orifice screw caps.

Is high and low speed orifice replacement is necessary? It takes a special tool to reach these.
 
It might be 'risky' using a std screwdriver that just happen to fit.
Go up a couple of sizes, then grind it so the tip gets parallel flanges and just fits into the slot in the jet. If the jets are a bit stuck it is easy to break off the top part. The original tool might in fact be a cheap investment. I have drilled out quite a number of 'home removals' in my time!!
 
Thanks. If the engine is running good is it necessary to replace the jets?

Just going by what the book said and I could not see well enough down the hole see the type of engagment tool would be needed.
 
I have the factory tool too.-----------But most can be taken out with a 3/16" diameter shank screwdriver.-------------Jets must be verified clean.
 
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