Cleaning low speed jets in a 67' Johnson 9.5

[thx997303]

This is probably not new to some, but it was quite a discovery for me.

I had my carb disassembled for a rebuild, and I couldn't figure out how to get at the three small orifices under the butterfly valve to clean them.

Well, I looked and looked and it seemed the only way to get to them was to pull a core plug, but I couldn't find the post I had once read describing the best way to do this, so I sprayed some carb cleaner on the three orifices and let the cleaner pool, and watched for where the cleaner drained out.

The cleaner drained out a small hole in the bottom of the casting, so I sprayed carb cleaner in that hole, and it only came out where the low speed mixture screw went in.

So, I plugged the hole where the Low speed screw goes, and voila! At first there was only spray from the center orifice, but soon after, I got full flow from all three orifices!

I believe these orifices to be where the gas comes in for the motor to idle.

Here are some pics.

http://i312.photobucket.com/albums/ll331/thx997303/Boat/100_2204-1.jpg

The above pic is of the offending orifices.

http://i312.photobucket.com/albums/ll331/thx997303/Boat/100_2207.jpg

The above pic is of the straw from the carb cleaner inserted into the hole, and the Low speed screw hole plugged.

http://i312.photobucket.com/albums/ll331/thx997303/Boat/100_2208.jpg

And the above is the result of plugging the hole and spraying the cleaner.
The flow actually looks like little geysers when going full bore with the cleaner, but I was trying to spray the cleaner, plug the hole, and take a picture at the same time, so It doesn't really do justice to the full effect.

Hope this helps somebody.

 

[Rick.]

Re: Cleaning low speed jets in a 67' Johnson 9.5

Nice post. I'm sure that will help us all to do even a better job of getting things clean. Best of luck. Rick.

 

[thx997303]

Re: Cleaning low speed jets in a 67' Johnson 9.5

Thank you, figured I ought to contribute to the forum if I can.

 

[kbait]

Re: Cleaning low speed jets in a 67' Johnson 9.5

I essentially do the same thing with a air can duster w/straw. For low speed circuit, there are 3 inlets when the needle is out. Needle hole, tube to bowl for fuel supply, and little holes in carb throat. If air passes through 'em, re-assemble.

 

[thx997303]

Re: Cleaning low speed jets in a 67' Johnson 9.5

I could get the other spots easy enough, but it took a minute to figure out how to get it to go through the three little holes.

I like the carb cleaner because not only does it clean, but you get a very nice visual when there's full flow.

 

[ezeke]

Re: Cleaning low speed jets in a 67' Johnson 9.5

By 1967 they had added the calibration pocket filler plug (312909) behind the core plug, so you can't get to the three holes that way without removing both.

More than half the time the filler plug won't come out, so blowing through the needle inlet or from the bowl is about the best you can do.

 

[thx997303]

Re: Cleaning low speed jets in a 67' Johnson 9.5

Hmm, I never even managed to get the core plug out.

 

[dukekas]

Re: Cleaning low speed jets in a 67' Johnson 9.5

Man that post is great guys, still stumped on what the calibration filler plug is?

 

[ezeke]

Re: Cleaning low speed jets in a 67' Johnson 9.5

Man that post is great guys, still stumped on what the calibration filler plug is?

It's a nylon filler plug placed behind the core plug on the later model 9.5 carburetors. It's clearly identified on the parts diagram as number 57 and should not be hard to locate.

 

[gintaras]

Re: Cleaning low speed jets in a 67' Johnson 9.5

I am glad that I found this thread, see my thread for a good picture of the filler plug..
http://forums.iboats.com/showthread.php?t=412916