video of my motor idling

[captmello]

would you experienced guys listen to my motor idle and let me know of it sounds ok, or of it sounds rough. this is the first start of the season. it's been running for around 5 minutes at this point and is idled down to about 800 rpm. it's a 2000 90hp 60 deg looper.
thanks.
View attachment 20220526_163038.mp4

 

[racerone]

Sounds like it is running on 2 cylinders.-----How did it run for you last season ?

 

[captmello]

it ran the same. it's run like this for years. I've had the boat/motor for 10+ years. when I first got the boat, I went through the carbs because the bowls were leaking. when under load, the motor will run a bit rough up to about 2000 rpm, then smooth out. It has performed well for as long as I've had it. it always starts and runs well. without knowing much about the carbs, I would think the idle circuits on two of the carbs is clogged. Is that a possibility? what do you think?

 

[jimmbo]

Do the standard Tests. Compression, check to see if the Spark can jump 7/16" gap. Check the Plugs, check the Float Setting, and the Sync between the Spark and the Carb

 

[captmello]

I did a compression test this morning. all the cylinders were at 125, same as they've been since I got it. I couldn't find my spark tester...I'll go buy another so the old one will appear. I'm not ready to pull the carbs yet, but I will once I can determine which cylinders are not firing at idle. I'm not sure how to check the sync between the spark and the carb that jimmbo mentioned.
I put the boat in the water today and ran it around for about 20 min. it ran good as always. reached 5500rpm, same as always. I'm still wondering if the idle circuits are bad on two cylinders, but I haven't had time to read up on how the idle is controlled. I had a two cylinder motorcycle once that idled on one cylinder but ran fine. it was a carb issue.
the boat in on a lift now so working on it will be a bit more challenging. I'm thinking I'll pull the plug wires one at a time and see which cylinders are not firing at idle. I'll pick up a spark tester to check spark on those cylinders at idle.
any other thoughts are welcome.
thanks!

 

[oldboat1]

Try it in a plastic trash can, water about half way up the shaft. They sound rough out of the water, but 800rpm might be a little low on muffs. See what it is in the test barrel or on the boat in the lake. Idle might be set a little low.

 

[captmello]

I'm back at this again.
here is where I'm at.
1. compression is at 125 on all cylinders
2. I tested for spark today and found good spark on all cylinders
3. I removed and cleaned what I believe are the low speed orifices on the carbs.
4. I pulled the plugs and checked the gap.
So I'm not sure what to do next. the motor has run like this for 12+ years.
One thing I noticed is that the spark plugs were wet when I removed them. all of them. is this normal? they are usually wet when I've removed them in the past. should I consider a hotter plug?
I have two weeks to mess with this before it goes on the lift at the lake.

 

[saltchuckmatt]

Sounded normal to me....

Plugs can be wet idling in the carport with muffs or a barrel. The plug should be checked after it's been ran around the lake.

Also, the idol should be put to its spec with it in gear under load. So that means when it's in neutral it will run a little higher. Those older two smokers can run good but they also don't like to idle a lot they were born for speed.

 

[saltchuckmatt]

Personally, I set the idle by ear.

 

[jimmbo]

I'm not sure how to check the sync between the spark and the carb that jimmbo mentioned.

That is why the Correct Service Manual is Important. But the basis is, the timing is required to be at a Specific Point, where the Carb(s) are still closed, but the slightest advance of the Timing, will be the start of the Carb opening, ever so slightly. And the all Timing Advance will also be in, long before the Carb(s) are fully open
Every Model, is different, and even changes from yr to yr, which is why I discourage people from using a Method buried on this Site.

 

[captmello]

Sounded normal to me....

Plugs can be wet idling in the carport with muffs or a barrel. The plug should be checked after it's been ran around the lake.

Also, the idol should be put to its spec with it in gear under load. So that means when it's in neutral it will run a little higher. Those older two smokers can run good but they also don't like to idle a lot they were born for speed.

thanks for the reply. I'm getting mixed feedback on this so I'm not doing anything too involved. as long as I'm not damaging anything. I've been sent down some rabbit holes before.
regarding the idle speed, I don't believe it is adjustable on this motor.

 

[captmello]

That is why the Correct Service Manual is Important. But the basis is, the timing is required to be at a Specific Point, where the Carb(s) are still closed, but the slightest advance of the Timing, will be the start of the Carb opening, ever so slightly. And the all Timing Advance will also be in, long before the Carb(s) are fully open
Every Model, is different, and even changes from yr to yr, which is why I discourage people from using a Method buried on this Site.

thanks! I've searched for a factory manual for this motor on occasion with no luck. with the exception of a slightly rough idle and a bit more vibration up to 2000rpm, the motor runs great. it has excellent throttle response with no hesitation at any time.
I may try a different plug and see if it has any effect. the non factory manual I'm using lists a different plug than I'm running now. I'm running the QL78YC,
the manual suggests running the QL77JC4 in oil injected motors. Any thoughts on this?

 

[racerone]

Sorry but idle speed is adjustable on most motors.----You just need to find where it is!

 

[airshot]

Mabey just my ears, but it sounds slower than 800 rpm...is the teach reading correctly?

 

[racerone]

Carburetor slow speed mixture screws may also need to be adjusted.

 

[captmello]

Sorry but idle speed is adjustable on most motors.----You just need to find where it is!

I misspoke the idle is adjusted by the timing. Not at the Carb. I don't think the idle adjustment is the issue. it idles fine but rough, on two cylinders you said.

 

[saltchuckmatt]

5500 RPMs, good popping noise, 12 years? Everything looks and sounds good. I still think that outboard just needs to be taken out for a good run.

If it sounds rough to you then maybe it just needs the carbs cleaned.

 

[flyingscott]

what is the cold idle at.

 

[captmello]

Carburetor slow speed mixture screws may also need to be adjusted.

this, you may be onto something.
Unfortunately, my nonfactory manual does not have the correct info about my motor. it doesn't think my carb has the idle mixture screws, but it does.
does anyone have a good manual that has the correct initial setting point for the screws?

 

[captmello]

what is the cold idle at.

not sure what you mean by cold idle, but when started cold, it idles high for a couple minutes, then idles down to between 800 and 1000 rpm in neutral.