Decarb Question

[scout-j-m]

I took my 94 70 hp to the mechanic recently to see if he could figure out what was causing the motor to run rough and cut out. He said the cutting out was due to the ignition system producing weak and unsteady fire on 2 of the cylinders. He also said the compression was 110, 110, and 90 which is low. Rebuilding the motor isn't really an option for me right now. The question is, can I do the Deepcreep decarb of just the 90 psi cylinder or do I have to do all three at once? My reasoning is I don't want the compression on the other 2 to come up only to find that the other one remained at 90. I'd like to decarb just the 90 psi cylinder, test the compression, decarb it again, and if it pulls up past 110 then decarb the other two as well to get consistent compression across the board. Will this method be ok to try?

 

[roscoe]

Re: Decarb Question

Decarb them all.
If you have weak spark, the motor needs a good decarb.

And eliminate all other causes of the condition, like water in the gas, dirty carb, idle too low, etc.

And what does the mechanic say is causing the weak spark?

Bad plug wires?
Bad coil?
Bad plug?

All easy and fairly cheap to replace.

This isn't rocket science, your mechanic should be able to diagnose this without throwing a bunch of unnecessary parts at it.

And that motor should still run ok at 90/110/110, not perfect, but not rebuild candidate yet.

 

[scout-j-m]

Re: Decarb Question

I will decarb all three cylinders and retest the compression. I do need to decarb twice don't I?

My mechanic said that the ignition problem was weak and inconsistent fire on 2 cylinders. I think he meant inconsistent as being sometimes a weak spark and sometimes a good spark causing those surges and cutting outs I was experiencing. What would cause this? Stator, trigger, rectifier, switchbox, coil, combination? He thinks it is the stator but he didn't do an in depth inspection since I just brought it in for a carb cleaning and impellar change. He recomended getting a new ignition system so it would be warrantied. I may get some electrical testing tools and try to figure it out on my own. None of it looks hard to replace just a little tricky to diagnose.

 

[scout-j-m]

Re: Decarb Question

Roscoe, can you give me the link or directions to the thread where you give detailed instructions for a decarb? I used to have it saved but I can't find it anymore. Also, where is Deep Creep carried? I don't recall seeing it at Walmart, only regular Seafoam. Is the best bet an automotive store?

 

[milehighboater]

Re: Decarb Question

Deep creep is essentially just arosol sea foam. I found cans of it at both Autozone and Checker. It is about 10 dollars for a can and should be enough to decarb the motor a few times. If it is too hard to find I will trim the motor up so the cylinders are vertical and pour seafoam into them and let it sit for an hour or so. Try to get all three cylinders in the middle so the seafoam just dosent pour though the reeds. It wont hurt anything but it wont decarb a piston either. Here is the link for the decarb:

http://forums.iboats.com/showthread.php?t=158076

or

http://forums.iboats.com/showthread.php?t=158076

They are the same link but I have never done the "insert link" option in these replies.

 

[roscoe]

Re: Decarb Question

Napa has Deep Creep, if not in stock, they can get it in 2 days.

 

[roscoe]

Re: Decarb Question

I will decarb all three cylinders and retest the compression. I do need to decarb twice don't I?

My mechanic said that the ignition problem was weak and inconsistent fire on 2 cylinders. I think he meant inconsistent as being sometimes a weak spark and sometimes a good spark causing those surges and cutting outs I was experiencing. What would cause this? Stator, trigger, rectifier, switchbox, coil, combination? He thinks it is the stator but he didn't do an in depth inspection since I just brought it in for a carb cleaning and impellar change. He recomended getting a new ignition system so it would be warrantied. I may get some electrical testing tools and try to figure it out on my own. None of it looks hard to replace just a little tricky to diagnose.

You don't need to do it twice, but it will get more junk out.

He recommends a new ignition for ??? $700-$1200 !!!
Not much of a mechanic if he can't test the ignition components and only replace the bad ones. And I'd really like to see the fine print on that warranty.

Sorry for my bad attitude, but its been a rough day, and I don't feel like sugar coating it.

The stator generates electric current, usually works or doesn't work. Appears to be working.
The trigger is a signaling device, that works with the switchbox, telling it when to fire. Appears to be working.
The rectifier converts ac current from the stator to dc current, used to charge the battery. Working?

Coil, old? fails intermittently when they start to fail? Possibly.
Old degraded sparkplug wires, possibly.

Now this is all without actually testing any of the components, which needs to be done.
I certainly wouldn't agree to let him start throwing $300 parts at the motor, if he can't even test them to see if they need replacing.

Seems strange that you are hesitant to have the bore honed and the rings replaced for a few hundred, but you think he should replace the ignition without knowing what parts are bad.

 

[cordell]

Re: Decarb Question

I replaced my ignition with parts off Ebay for under $200. It took some reading and a 2 day long head ache but I did it. I have a 3 cylinder and the ignition came from a 4 cylinder. And before I had the black coils but when I replaced I had the blue ones! I did have to get a 3 cylinder trigger though but the rest is from the 4 cylinder motor. Now I have a spare coil and a un-used spot on a CDI

 

[scout-j-m]

Re: Decarb Question

Still haven't had time for a decarb yet but I read up on the ignition system in my clymer manual. It didn't really say anything about checking the working condition of individual parts of the ignition but rather only how to remove and reinstall each part. Am I missing something in the book? How should you go about testing the ignition system part by part?