Jonny/Rude Carb Jet Questions

Bill kubiak

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Is it possible for all the brass jets and adjusting screws inside the carb in an older engine to wear out??<br /><br />If so, How can I tell???
 

Dhadley

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Re: Jonny/Rude Carb Jet Questions

It would help to know what motor we're talking about but I guess in theory the fixed jets could wear out. I've never seen that personally but I guess so. Highly unlikely. What is common is that as the fuel changes each year, some motors react differently.<br /><br />As for the adjustment screws, folks tend to "seat" them too hard/far/tight and that can create a "groove" in the tip. Then its time for a new one.<br /><br />Again, what motor?
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

it's a 1961 johnson 3 hp Jw-17s
 

Dhadley

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Re: Jonny/Rude Carb Jet Questions

And what is it doing or not doing that you'd like to change?
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

it sputters and will not fully start and run, if I choke it the carb floods, I have put a carb kit on it and wondered if it was possible that the hi and low speed needle valves and seats plus the jets were worn out from 45 years of use
 

Dhadley

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Re: Jonny/Rude Carb Jet Questions

Did you soak the carb? If so, in what?
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

I sprayed carb cleaner thru all the openings, I even knocked out one of those alum plugs and cleaned and replaced it. I am fairly sure all the openings are free and ubobstructed
 

Paul Moir

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Re: Jonny/Rude Carb Jet Questions

Evening Bill.<br /><br />A few problems common to the 3hp's:<br />1) Cracked ignition coils which arc over at higher rpms. May deliver good sparks at pull-start speeds. They're easy to inspect on your engine since you can look through the holes in the top of the flywheel, under the thin cover plate. If you see cracks in the insulation, I'd be willing to bet that this is your problem.<br />2) Clogged fuel filter. Causes engine to run for a few seconds and then quit for a few minutes, sometimes only with less than 1/2 a tank. Probably not your problem, but worth knowing about. It's above the brass nut on the tank above the fuel spigot.<br /><br />Did you ever get the screen for the front of the carburator replaced? It's a perforated peice of aluminum. Do you have the intake silencer attached?<br /> Nice article.
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

I did not know about the fuel filter inside the gas tank,<br />I do not have the airbox nor the alum screen, what do they look like (do you have a photo) perhaps I can fabricate something
 

Paul Moir

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Re: Jonny/Rude Carb Jet Questions

Bill, I don't have a picture, but here's one here. The silencer is the thing over the mouth of the carburator, which wraps around the side. It's attached to the exhaust cover plate. This directs the intake to the back of the engine.<br />The screen is sandwiched between the carb's mouth and the silencer, and partially chokes the engine. It's something that would fit fine in an envelope, if you had to buy one. Say from Twin City Outboards. <br />I don't think the silencer effects how the engine runs. But the screen certainly does.<br />Sorry, I can't get to my 3hp right now. Otherwise I'd give you those screen dimentions.
 

bidlimit

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Re: Jonny/Rude Carb Jet Questions

I replaced the needles and seats on my '57 Lightwin (same as stated 3hp Johnson). I put in a carb kit, along with all new ignition components. My coils were also cracked badly. Try www.boatfix.com for parts, they are cheap and offer fast turn around. These motors are pretty darn indestructible; a carb kit and all new ignition components should make it run providing the compression is good.
 

OBJ

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Re: Jonny/Rude Carb Jet Questions

Bill....just a thought here....what kind of settings do you have on the needles? Don't take much to make these critters run.
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

I had 1 1/2 turns open on the low speed and 3/4 turn open on the high speed,<br />I took the two adjusting needle valves out and looked at them under a 5X jewelers eye piece and noticed that they were all scored up and scratched. So I just put them in a drill and ran some 400 grit emery cloth over them until they were fairly smooth and shiny again.<br />I was thinking to make an intake screen from a piece of alum and drill a bunch of tiny holes in it. Do you think that will work. I just got a factory OEM manual off E Bay and it does not show any screen or even the air silencer.<br />I pulled the valve from the gas tank and cleaned the screen, it was cruddy. the inside of the valve itself was cruddy. Perhaps that was why it kept flooding. Junk kept getting under the float valve seat. What is a good method to clean out the tank itself?
 

bidlimit

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Re: Jonny/Rude Carb Jet Questions

Those Johnson equivilents did not have them; they were reserved for the "quieter" Evinrudes. I wouldn't worry about it.
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

Bidlimit I am not sure what you are saying that I do not need. People here are telling me that the screen is very important and I need to have it.<br />Do you know what it looks like??
 

bidlimit

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Re: Jonny/Rude Carb Jet Questions

My 57' 3hp Lightwin (same as Johnson) had the "tuned" airbox. It was basically a big aluminum tube that was shaped so that it canceled out intake noise. Evinrude tried to make its engines as quiet as possible in the 50's; it was touted as a big feature. Johnson was the cheaper brand and did not have the special noise cancelling features until the late 50's early 60's with the Superquiet exhaust routing system introduced on larger engines. If the diagram does not show a screen, don't worry about it. I have run many small engines without screens, besides, the ones commonly used on these engines wouldn't work as flame arrestors anyway. Even so, your 3hp cowling is open on the bottom so if there ever was a fuel leak (which there shouldn't be in a simple fuel system like this one) the fumes probably wouldn't catch even if there was a backfire through the carb. A backfire on these engines is rare. Do yourself a favor and don't worry about the screen.
 

bidlimit

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Re: Jonny/Rude Carb Jet Questions

Here's another tip. Definitely take the fuel tank off and disconnect the petcock and fitting from it. Clean the tank out well. I say to do this because those sintered brass filters rotted very easily. You may be getting pieces of it stuck in the copper fuel line and in the carb. I would also disconnect the fuel line competely and blow it out with compressed air to get the stuff out. Mine was competely decentigrated, I didn't even know there was one there until I stumbled upon a cutaway of the engine on the internet. Be wary of the crimped on threaded piece in the tank too. (The thing the petcock screws into) They like to work themselves loose over time, I had to have mine welded. One more thing. The copper fuel line uses compression fittings; check these out for leaks and replace if necessary. Hope this helps!
 

bidlimit

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Re: Jonny/Rude Carb Jet Questions

The old Evinrude user's manual says to seat the needles and back em' out 3/4 turn....I wouldn't worry about the high speed yet, get it idling first. I got tired pulling mine, so I hooked up a 1/2" drill with a socket adaptor to the flywheel nut and cranked her over that way. It made it very easy to work on, just be careful you don't rip it apart. ;)
 

Joe Reeves

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Re: Jonny/Rude Carb Jet Questions

Bill.... The only way to clean a carburetor is to remove, dismantle, clean, and rebuild it. The proper adjustment procedure follows:<br /><br />(Carburetor Adjustments - Two Adjustable N/Vs) <br />(J. Reeves)<br /><br />Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns. <br /><br />Setting the high and low needle valves properly: <br /><br />NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.<br /><br />(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting. <br /><br />(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. <br /><br />When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 

Bill kubiak

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Re: Jonny/Rude Carb Jet Questions

I understand everything all of you have said and really appreciate your input.<br /><br />The motor tries to start but will not sustain itself, If I choke it, the carb floods immediatly and fuel drips out of the carb intake.<br /><br />This engine did not have a carb screen? or an airbox when I got it. Paul Moir said this screen makes it run partially choked because there is so little suction.<br /><br />I am fairly good and making things run, but this engine has me stumped.<br /><br />When I had it apart I noticed that one piston did not have those little pins in the ring groove to keep the rings from turning, could that be a problem here. The compression is fair on both cylinders, it pumps up to around 60 psi on each one and when the engine does try to run it is very quiet, it just will not keep running.
 
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