First test run after new rings, running rough.

[healey8390]

86’ 110. I might have a driveway queen on hands. Did a link and sync, getting spark to jump 7/16.

When I put it in the water it wouldn’t idle so I turned the timing out about and it’s better but still stalls sometimes. I sputtered and sounded like it was missing and then it cleared up.

I took it out, wasn’t hard on it but my boat is very hard to plane so I did have to get on it a little. Well, it started doing this chugging/spitting thing with a pretty moderate jerk and mid to higher rpm. Then it started doing it a low and maybe all rpms.

On the other hand, when I had to give it gas to on the the trailer it ran fine??

I didn’t bring the timing light so I’m kicking myself in the a$$.

I’m going to check timing and spark again and I need to check compression. Video link attached please let me know if you have any suggestions.

https://youtu.be/qe4W8wjmyV8

 

[healey8390]

Sorry for the horrible grammar.

 

[Tourtney]

Put the old rings back in, just kidding. How come you changed the rings? (Piston rings I assume) I would look into compression comparison before and after.

 

[healey8390]

Sure lol. Overheated from shallow water. I did two pistons the right side was fine.

 

[havoc_squad]

Definitely dropping a cylinder or two, you can see the motor throwing a fit while in gear under load.

Why doesn't it act up while not in gear or on muffs out of the water you ask? There is no load. Load means resistance.

A motor in bad shape can rev up to red line RPMs with no load. Soon as you put a load on a bad motor, it operates terribly.

That itself isn't a sign that it only is a compression issue, but that's one of the first things a technician checks.

A motor running well will perform properly when it has the proper amount of resistance/load applied.

What was done to verify that your cylinders were in spec when you noticed damage?

Did you get a machinist or use precision tools (micrometer & dial bore gauge) to verify the bores were in spec according the OEM service manual and that no score marks that have to be bored out?

Unless piston kits are no longer available, re-ringing a two stroke motor is definitely frowned upon, most likely is due to the uneven wear it causes. It requires a new piston and the matched new rings to be matched to the possible cylinder sizing if oversizing is needed.

I think your compression numbers are going to tell you that you'll have to tear down that motor and send that block off to the machine shop. Just a guess, but very likely an accurate one.

 

[racerone]

I would say your motor has some serious issues.------New rings in factory original pistons is a MISTAKE !!----And they all " bark and roar " on a trailer and that means nothing.-----Time to do some more trouble shooting I say.

 

[healey8390]

Getting a gauge today will report back in a few hours. If it IS bad compression then why did it power up the trailer and not jerk and sputter then? Is that not a load? Why did act up at mid to higher rpms first, then at low rpms? Sounds erratic/intermittent to me. I’m thinking a compression problem would be consistent but I’m far from an expert... Crossing my fingers. Hope to report good new on that front.

 

[havoc_squad]

Getting a gauge today will report back in a few hours. If it IS bad compression then why did it power up the trailer and not jerk and sputter then? Is that not a load? Why did act up at mid to higher rpms first, then at low rpms? Sounds erratic/intermittent to me. I’m thinking a compression problem would be consistent but I’m far from an expert... Crossing my fingers. Hope to report good new on that front.

A load means the engine is doing a specific task or purpose that encounters an expected amount of resistance. (work)

What is the difference between you lifting up a smart phone and large cement block, or what is the difference between you going downhill on a bicycle versus up a steep hill?

Lifting that brick and going up that steep hill requires work.

The only time a boat engine does work is when in gear in the water or in gear on a dyno machine.

Compression loss = loss of power and RPM under load.


As stated beforehand, the only way to know the issue for sure the issue is check. Compression and spark are the first two that are easiest to check. The other two (fuel and air) become relevant only after the first two are both good.

 

[IDFISHER]

I believe what the OP is saying is that the boat was in the water and he had power it up onto the trailer, not that it was sitting out of the water on the trailer. Powering onto the trailer would constitute a load.

 

[havoc_squad]

I believe what the OP is saying is that the boat was in the water and he had power it up onto the trailer, not that it was sitting out of the water on the trailer. Powering onto the trailer would constitute a load.

Quite possibly, that was a bit confusing to read.

Anyways, there's not much really to say until the OP comes back with those compression numbers.

 

[healey8390]

Yes I meant powering the boat from the water up onto the trailer. First post was horrible.....

I think it needs a power pack, the top left cylinder is cutting in and out. Here's the rundown:

I was going to start with a spark gap test first. I was checking the connections of the power pack output wires to the coils and I found the top left coil's terminal that the wire plugs onto was loose, it was unscrewing. It's an aftermarket coil, I don't think the OEM ones can unscrew like that but I'm not sure. I got excited hoping that was the problem and snugged it up and moved to the next test.

I tested the stator, the manual says 585 ohms max. I got 620 on both sides so a little high. Trigger called for 40 +/- 10, I got 35 on both sides so good.

Next I did the compression test. I got 105, 105, 104, 112. I'm disappointed but it's over 100 and within 10% on all four. If I'm lucky it's the gauge, I spent $30 on the gauge. Maybe maybe the numbers will raise a little too once it breaks in but If the numbers are true I can live with it. I'm only planning on keeping the boat for a year or two anyway.

I checked the timing, I had to adjust the idle timing. WOT was fine at 24 which apparently will go to 28 running at WOT with a load.

I went ahead and started it, it seemed like it ran fine for a few seconds but then it started to slow down and then surge. I put my timing light on the top left plug wire where I had the coil issue and sure enough the light went on and off consistent withe the engine slowing and speeding up. I went ahead and put a good backup coil on and the problem stayed. Then I put a spare power pack that I thought may have been bad but not sure and it went from firing on all four but sounding weak to the left side not firing at all.

Soooo, I think It's a power pack. Yes the stator is a little high but it’s the same on both sides so I don't think it would cause a problem only on one side like that but I could be wrong.

 

[healey8390]

So I bit the bullet and bought two new power packs. I figured if one is bad and as old as they are I might as well do both.

I took it out today and it still did not want to idle for the most part. I have to have the warm up lever up for it to keep running but sometimes it will idle without it so I think there still may be a cylinder cutting in and out but I’m not sure.

I brought my timing light and all four cylinders flash. I had to adjust idle timing. I did it to four degrees, please correct me if I’m wrong.

I went ahead and took it for a spin and it ran really good. It jumps up on plane and sounds healthy & powerful but I just can’t get it to idle.

i wonder if the coils are going bad? It has passed a 7/16 spark jump test but they are really old. I threw out the other new aftermarket ones I bought because they wouldn’t pass the test and I didn’t like how the terminal unscrewed. Now I’m wondering that they were good but the old power packs didn’t have the umph to fire them?

I’m trying to avoid blanket diagnosing and buying a stator and trigger but I may be headed down that road. I think I’m going to start with coils but a different brand.

Also, the positive battery cable seems like it could be replaced. It doesn’t have corrosion but the copper is black. I wish it was something that simple but if the engine cranks with no problem then am I safe to assume it’s getting enough juice to properly fire the ignition? Any other Ideas? Also

 

[racerone]

At this time you might as well install a new stator & trigger.----It was not the powerpacks , was not the new coils that were defective.----So it must be the stator / trigger that are now bad.

 

[tblshur]

mr healey 8390 just wanted to say these gentlemen are just trying to save you some money and help you they are greatly qualified that said i know how it is when one makes some progress i would be very interested if you would keep us posted may be help to someone someday (like me) :joyous:

 

[healey8390]

I put a new stator on it and it it was better but still not right in my opinion. It still stalls at idle but just occasionally now and it still sounded like a cylinder (or more) was cutting in and out. It still ran great at high rpm though and top speed is 37mph gps. It's a pretty deep/heavy hull for a 16 footer IMO so I'm assuming that's an ok top speed. It's an old Wellcraft Airslot 165.

Anyway, I found a spark plug tip was loose, it was starting to unscrew. I didn't even know that brand was that style... What is going on with things unscrewing on this boat?? One of the coils had the same issue with the tip that the power pack plugs onto. Did I even need the stator? Who knows... I checked the other plugs and they were fine. There was an improvement, the low speed miss is gone and now it will idle 85% of the time including in gear but it still dies sometimes. Also, it does seem a little rough until about 3/8 throttle then it clears up. It's not much, no jerking like before just seems a little uneven until more rpm's. Last, after sitting at a fishing hole I need to use the fast idle until it catches. I don't remember having to do that before the rebuild. Average time at a fishing hole is 30-45min.

My concern is that if I have done the link and sync correctly that if I adjust the idle anymore, the cam will now be opening the carbs, but from what I've read the butterflies should be closed at idle so this would be incorrect??

Also, when I did the link and sync, the book says when the cam is in the center of the roller, the timing should be 4 degrees BTDC. To make it do that I had to screw the linkage to the cam follower out one full turn. Once again, I did not have this issue before the rebuild.

I'm truly stumped here. My only other guess is the fuel pump diaphragm. Maybe it's weak and doesn't pulse good at idle? On the other hand I've read they last a long time so once again here I am second guessing myself. Let me know what you think thanks again.

 

[healey8390]

OK here we go on the idle saga of 2020... I feel like a moron, I found I didn't put the bottom carb gasket that goes between the carb and manifold!!

I checked the link connecting the carbs to make sure they were opening at the same time. Checking the manual again it said to push down on the link and then tighten the screw. I was glad I seen that because I remembered pushing up on the bottom carb connector to take the slack out. I made the adjustment and took the boat out for a test and it ran the best it has. Started up great, Idled in neutral and in gear. However, sometimes it would still seem like it was about to die at idle in gear. Yet again inconsistent. I used the boat two more times and was generally happy other than the slight inconsistency and that the last time, Saturday, it did a hard start after being at a fishing hole for about 30 minutes, I had to give it fast idle for it to catch.

I was pondering taking the boat out today but I decided to mess with it again. I ran it on the hose first to flush it and it would barely run and coughed here and there and would surge. It would go between "catching" and slowing and coughing. I put the timing light to check idle timing and it seemed ok. When I do that I have the engine turned to the left to be able to get to the timing light plug connector easy while I'm in the boat. I figured let me check the other side so I turn the engine all the way to the right to have the easy reach and well, when I turned the motor to the right it ran a lot better, seemingly normal. It took a couple times of checking the right and left side to catch on to this anomaly. I did it multiple times and sure enough when the engine was turned right it ran better. My driveway slants down toward the street so I was thinking maybe a float needle isn't sealing 100% or something or maybe the fuel pump diaphragm. Then again I said to myself that a diaphragm would probably be a consistent problem.

I went on to take the carbs apart to inspect. After I removed the air box that connects to the carbs I noticed the missing gasket. I was shocked yet happy at the same time. I will get a gasket in the next day or two. I can't believe I did that, always double check your work!! This costed me a stator though I did have a little bad luck with the coil tip unscrewing and spark plug tip also unscrewing.

My first thought when confirming the problem is dang I hope I didn't run lean so i need to check compression but I can't believe it ran as good as it did like that so I think I got lucky.