Motor bogs down: Cleaning high speed jets, loose bolts

1984 evinrude 50hp 2 stroke with a outboard jet conversion. While I'm probably capable of removing the carbs and cleaning them, I'd like to avoid it til spring if possible.
I've had the boat out a few times and it bogs down when accelerating. It doesn't start right up like a new motor but idles pretty well. Once it warms up, it'll run wide open just fine. If I choke it at full throttle, it runs much better. From what I've read and been told by the previous owner, it's the high speed jets that could be clogged.

The bolts that sit in the holes housing the high speed jets weren't tight. The top one (as shown) was a couple turns out. I removed the jet and it was clear.
The washer for the top low speed jet is missing. I'm guessing that's not helping either.

When I removed the bolt for the bottom high speed jet, a couple ounces of fuel ran out. I didn't mess with it further because I can't get the screwdriver in there and I'd rather not remove the carb today. If I have to rebuild the carbs after this, I'll do so.



Thoughts?
I should note: It sat for 2 weeks before I took it out last and it took me several minutes to get it started. It certainly doesn't fire right up like my mid 90's evinrude.

While neither one of the issues that you describe below are good, I don't think either one of them would greatly affect your performance.

1) Bowl Drain screw - As long as you didn't have any fuel dripping around this screw, it wouldn't affect performance. It should be tight against the bowl and not leaking. If it was leaking significantly, then it could possibly lower the level of fluid in the bowl and cause a lean condition.

2) Missing screw gasket - Again, not critical. You should replace the gasket (included in a carb rebuild kit). But the screw threaded in place will provide sufficient resistance to prevent any significant vacuum loss.

Where is your power loss occurring? Is it happening immediately off of idle? Is it throughout the mid and high ranges?

If you see a big improvement when you apply the primer, then I wouldn't run the motor for any length of time. A lean condition can easily cause piston or cylinder damage which would be far worse than a carb cleaning. If it's not running right, don't use it for anything other than quick test runs.

High speed jets could be plugged. Could also be the intermediates which operate when the butterfly is just opening. Either way, for the effort, you should probably disassemble the carbs and clean them as best you can. Half of the work is already done with the airbox already removed. Shouldn't take more than 1/2 hr per carb to do.

Make sure to do a Link & Sync when you install the carbs.

Good luck!

Kofkorn has given you some good advice. Do NOT run a two stroke lean (which is what it is doing).
The idle jet may not need a washer behind it. It should be an air bleed in that carburetor, not a fuel jet.
Also, check the prop pitch for your application. Too much pitch can really aggravate and create a bog in a two stroke.

"Where is your power loss occurring? Is it happening immediately off of idle? Is it throughout the mid and high ranges?"

Immediately off idle and throughout the mid range. It's fine in the high range once warmed up.

No prop, it's a jet.

If it is just off idle, check your timing sync. Make sure that when the timing cam is hitting the roller on the carb, the mark on the cam is aligned with the center of the roller. What you describe can be caused by the timing not advancing far enough before the butterfly starts to open. When this happens, the lower RPM of the motor doesn't create enough vacuum to draw fuel out of the intermediate venturi(s). Suddenly your motor is running lean and stumbles dramatically.

You can correct this by adjusting the timing cam on the threaded rod. If you pull the cam back, it will advance the timing further before contacting the roller. You'll have to look for a manual to determine the correct adjustment.

I had a similar problem with my 1988 50hp when I purchased it earlier this year. After adjusting the timing cam back, it takes off very strong.

Good luck!

kofkorn said:

If it is just off idle, check your timing sync. Make sure that when the timing cam is hitting the roller on the carb, the mark on the cam is aligned with the center of the roller. What you describe can be caused by the timing not advancing far enough before the butterfly starts to open. When this happens, the lower RPM of the motor doesn't create enough vacuum to draw fuel out of the intermediate venturi(s). Suddenly your motor is running lean and stumbles dramatically.

You can correct this by adjusting the timing cam on the threaded rod. If you pull the cam back, it will advance the timing further before contacting the roller. You'll have to look for a manual to determine the correct adjustment.

I had a similar problem with my 1988 50hp when I purchased it earlier this year. After adjusting the timing cam back, it takes off very strong.

Good luck!

Click to expand...

Well, it looks like this at full throttle, 3/4 full, and neutral:
engine not running in these pics.
In case I didn't mention it, I am NOT a mechanic but I can figure most things out. I work on my cars when I have to. This is the first time I've done anything to an outboard other than change plugs.

Your linkage looks pretty good. But it's very hard to tell visually. Just make sure that at idle, the roller doesn't touch the cam. It should be about 0.010" between the two. If you've got feeler gauges, you can use them to easily set the gap. If it is touching, then the butterflies on the carbs will open too early. Use the slotted pan head screw to adjust the roller. I would err on the side of too much gap rather than too little.

Another thing to check is to make sure both butterfly valves are completely closed at idle, and that when pushing on the roller they both begin opening at exactly the same time. If they don't open perfectly together, you'll need to adjust the linkage at the top carburetor to get them linked properly.

All of these little details make a significant difference at idle and low speeds.

Good luck!

I cleaned the high speed jets before tearing the boat apart to remove all the waterlogged foam so didn't get the chance to test my work until yesterday. Runs like a champ!