19XX Johnson 3hp 2-Stroke Help

[jrs_diesel]

Re: 19XX Johnson 3hp 2-Stroke Help

Oh ok. Most all of the newer 2 and 3 HP Johnsons I've seen have both a high and a low speed needle. If it is only one, then it's a low speed needle. Screw it all the way in until it seats, be gentle though or you run the risk of getting the needle tip stuck in the carb. Once it's seated, turn it back out 1 ? turns. That's the baseline setting. Then advance the throttle to the start position (should be marked), pull the choke out and try to start it. It should fire within 3 or 4 pulls. Once it's warmed up, then you can decrease the throttle and set the low speed mixture screw for a good idle.

Turning the screw in (clockwise) makes the mix lean. Turning the screw out (counter clockwise) makes it rich. Find the spot where it will idle the best and then turn the screw out 1/8 of a turn (rich). Too lean is bad for two strokes.

Once you get it dialed in it should idle well, and not hesitate when you increase the throttle.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Oh ok. Most all of the newer 2 and 3 HP Johnsons I've seen have both a high and a low speed needle. If it is only one, then it's a low speed needle. Screw it all the way in until it seats, be gentle though or you run the risk of getting the needle tip stuck in the carb. Once it's seated, turn it back out 1 ? turns. That's the baseline setting. Then advance the throttle to the start position (should be marked), pull the choke out and try to start it. It should fire within 3 or 4 pulls. Once it's warmed up, then you can decrease the throttle and set the low speed mixture screw for a good idle.

Turning the screw in (clockwise) makes the mix lean. Turning the screw out (counter clockwise) makes it rich. Find the spot where it will idle the best and then turn the screw out 1/8 of a turn (rich). Too lean is bad for two strokes.

Once you get it dialed in it should idle well, and not hesitate when you increase the throttle.

I will do that, sir! Thank you!

Say it doesn't start in those few pulls.. Where should I look next?

As I said, getting fuel, the carb was full the last time I pulled it annnd I know I have spark.

 

[jrs_diesel]

Re: 19XX Johnson 3hp 2-Stroke Help

Not knowing the life it lived before you got it, it could have low compression. That can cause a hard to start problem.

When you cleaned the carb did you clean the idle passages under the welch plug (silver looking disc on the carb). The welch plug is a lead disc, and a new one is included with new carb rebuild kits. There a couple of tiny holes under that disc that need to be squeaky clean for it to idle well.

How far did you turn the throttle to start it? If the throttle is set to low you will have a heck of a time starting it. It can run at a higher throttle setting too, even if the idle passages are clogged.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Not knowing the life it lived before you got it, it could have low compression. That can cause a hard to start problem.

When you cleaned the carb did you clean the idle passages under the welch plug (silver looking disc on the carb). The welch plug is a lead disc, and a new one is included with new carb rebuild kits. There a couple of tiny holes under that disc that need to be squeaky clean for it to idle well.

How far did you turn the throttle to start it? If the throttle is set to low you will have a heck of a time starting it. It can run at a higher throttle setting too, even if the idle passages are clogged.

I'll pull the carb and check on that to see if it is clogged. Getting good at tearing this thing down lol.

I have the throttle set at "Start". We tried getting it to start with the throttle set higher, lower, choke in, choke out...

Frustration continued tonight. Went out and bought a drill bit so I can use sockets with my drill. Before I got started though, I pulled 1 of the 2 plugs, stuck my thumb over the hole and gave it a turn. I had pretty good amount of air pressing on my thumb, so I'm guessing I have decent compression. Noticed after some trying though, the plugs weren't wet or didn't smell like gas... Not sure if gas is getting to them or not.

Tried a lot to start it with the drill, no luck. Gave it a little kick of starting fluid, it would chug a tiny bit but that is it. Sure beats trying to pull start it though.

Anything else I should pull from this thing to check?

 

[nwcove]

Re: 19XX Johnson 3hp 2-Stroke Help

If you continue to use a drill on the flywheel nut, you will most likely damage the flywheel taper due to over torqing it. Try putting a tbsp of premix in each plug hole and see if it will make a good kick.
and holding your thumb over a plug hole to test compression is pointless......all it will tell you is that there is a piston in the cyl. jmo

 

[jrs_diesel]

Re: 19XX Johnson 3hp 2-Stroke Help

Pull the spark plugs and squirt a little 2 stroke gas into the cylinders. Put the plugs back in and see if it will run a little bit. If it does, you have a fuel delivery issue. Could be as simple as a dirty carb. Reed valves could be stuck from sitting, a gasket issue even.

Start simple and work your way up. Small carbs are more sensitive to clogs and debris. When you open yours up again, use some copper wire and make sure the small passages are clean and clear. You can also use pipe cleaners (real ones for pipe smokers, not the arts and crafts type) to clean the larger passages and jet with carb cleaner. Real pipe cleaners are usually made with cotton fibers and are thinner, great for cleaning. The arts and crafts variety are terrible at cleaning anything.

I'd go through the carb before anything else. The plugs should be slightly wet with fuel after cranking for a while and not running. My 9.9 did that when it's ignition died. I cranked on it for a while and then checked the plugs. They were noticeably wet with fuel.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Pull the spark plugs and squirt a little 2 stroke gas into the cylinders. Put the plugs back in and see if it will run a little bit. If it does, you have a fuel delivery issue. Could be as simple as a dirty carb. Reed valves could be stuck from sitting, a gasket issue even.

Start simple and work your way up. Small carbs are more sensitive to clogs and debris. When you open yours up again, use some copper wire and make sure the small passages are clean and clear. You can also use pipe cleaners (real ones for pipe smokers, not the arts and crafts type) to clean the larger passages and jet with carb cleaner. Real pipe cleaners are usually made with cotton fibers and are thinner, great for cleaning. The arts and crafts variety are terrible at cleaning anything.

I'd go through the carb before anything else. The plugs should be slightly wet with fuel after cranking for a while and not running. My 9.9 did that when it's ignition died. I cranked on it for a while and then checked the plugs. They were noticeably wet with fuel.

We sprayed gas into the spark plug holes and we were able to get some good chugs out of it and even some exhaust..

Pulled the carb, cleaned anything I might have missed. Everything still appears very clean in there. We also pulled the cylinder head off and a lot of water came pouring out of the cylinders. Definitely not helping. Not sure how long that has been there, it was left in the rain though.

EDIT: We turned it over a bunch with the cylinder head off, all of the lower ports squirted water from them. What we can't figure out, is how fuel is supposed to be delivered from the carb to the spark plugs to get ignited. That is where we think our problem is.

EDIT II: Pulled the carb and I don't know why I never checked, but I found and pulled the pilot jet and cleaned that. Now when we turn the engine over, after awhile we get some small amounts of fuel being sucked from the pilot, fed to the main and it pours into the carb. Small amounts, but more than we saw before (I think). We also sprayed fuel into the reeds and watched the pistons as we turned it over. We finally figured out where the fuel is supposed to go and where it's supposed to come from. We saw the fuel come from the vents on the cylinder walls and get pushed out. Now we are just wondering if there is enough suction to pull enough fuel from the bowl, to the carb, to the cylinders. Waiting on a compression tester... We don't see any signs inside the cylinder walls, the pistons or rings to tell us that we have bad compression. Unless we have a bad gasket somewhere....

Pistons looked really good and turn very smoothly. We also watched the reed valves both open as I assume they should. How far are these supposed to open? I'm guessing not very far?

Gonna throw everything back together and give it another whirl here in a bit!!

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

LIFE!!!!

We got it to start and run for a minute or two.

It will only run though if the throttle is set halfway between start and full, not choked and if the air/fuel mixture needle is turned all the way in or slightly backed out.

We first got it running on turning the A/F needle 1.25 turns out.. but it didn't like that after running awhile.

So now what is our problem?

 

[jrs_diesel]

Re: 19XX Johnson 3hp 2-Stroke Help

Awesome!

They only thing that comes to mind about water in the cylinder would be a bad gasket, likely the head gasket or even the exhaust plate gasket.

The low speed needle does not do much for high speed operation. Every carb is slightly different in its adjustments, that is something you'll have to get dialed in. The needle on my 9.9 is almost all the way in and it's just about perfect. I had an idle issue on it too, just had to readjust the throttle linkage.

Check your link and sync. There should be a throttle cam on the timer base that engages the cam follower/roller on the carb. There is a mark on the cam, that needs to line up with the roller as you throttle up. The roller should also be perfectly round, no flat spots.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Awesome!

They only thing that comes to mind about water in the cylinder would be a bad gasket, likely the head gasket or even the exhaust plate gasket.

The low speed needle does not do much for high speed operation. Every carb is slightly different in its adjustments, that is something you'll have to get dialed in. The needle on my 9.9 is almost all the way in and it's just about perfect. I had an idle issue on it too, just had to readjust the throttle linkage.

Check your link and sync. There should be a throttle cam on the timer base that engages the cam follower/roller on the carb. There is a mark on the cam, that needs to line up with the roller as you throttle up. The roller should also be perfectly round, no flat spots.

Definitely going to make a video so you can see. Might help a bit more. What I can't tell, is if I'm not getting enough fuel, or if I'm not getting enough air.

Either way, glad to see it running. Maybe I need to clean the jets a bit more? Let them sit in carb cleaner.

 

[jrs_diesel]

Re: 19XX Johnson 3hp 2-Stroke Help

Most auto parts stores sell a carb dip, comes in a 1 gallon can. All you do is make sure there are no rubber or plastic pieces on the carb and put it in the carb dip overnight. Follow up with compressed air and pipe cleaners and reassemble. Make sure all seals and gaskets are in place.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Alright, so we cleaned the carb out like crazy and tried this beast again.

This time, we are getting a really good idle, but the motor will die if we turn the choke off. It only likes to run just where it is at in the video below.

Any ideas? The only (obvious) thing I can think of is that it's not getting enough fuel. Not sure how to remedy that. Could this engine be getting just enough compression to let it run, but not enough to pull enough fuel from the carb? Or is that not how it works?

Also, we obviously have LOTS of smoke.. we bumped the fuel mix down from a 25:1 to a more 40:1 or 50:1 mix.

 

[F_R]

Re: 19XX Johnson 3hp 2-Stroke Help

Did you inspect the high speed jet (orifice plug) in the carburetor? Did you even notice it has one? It is deep in the hole behind the hex head drain screw in the carburetor bowl. It must be absolutely, positively CLEAN with no hint of any dirt, gum, or varnish. But don't be going jamming wires and drills & stuff through it. That is a precision hole and oversize is just as bad as clogged.

 

[deputy865]

Re: 19XX Johnson 3hp 2-Stroke Help

Did you inspect the high speed jet (orifice plug) in the carburetor? Did you even notice it has one? It is deep in the hole behind the hex head drain screw in the carburetor bowl. It must be absolutely, positively CLEAN with no hint of any dirt, gum, or varnish. But don't be going jamming wires and drills & stuff through it. That is a precision hole and oversize is just as bad as clogged.

Yeah, pulled that and cleaned it out thoroughly. Do I need to do it again, just in case? It's easy to get at and we have LOTS of carb cleaner lol.

 

[Tim Frank]

Re: 19XX Johnson 3hp 2-Stroke Help

As already stated, a compression test is really advisable.
Beg, borrow, or buy a tester.
You may be wasting your time with this if you don't know the compression status.