Replacing the Magneto on an 084

[Papee]

Perplexing, I have the mag turned down until it hits the engine block. It idles rough but seems to be turning more rpm than before. I don't have the tach hooked back up yet. I can't get any more advance in it because of it hitting the block, it also starts very easy in that position. I'm wondering if I need to move the mag a tooth but it seems if everything is set right it should run right with all the correct factory settings and not have to move anything. I'm wondering if the mag gear is 180* out, it could go on two ways.

Guess I'll take it back off and change the gear 180* and see what that does first. I'll be an expert til this is done. I'm a good one for learning the hard way. At least we'll know all the wrong ways to do it, you'll be able to troubleshoot from this thread.Thinking out loud is dangerous.

[Papee]

Well that didn't work. Guess I'll change it back. I looked at the gasket on the intake tube I had to take off to get the Fairbanks mag off. I reused the gasket.

Round 57.4 I'm gonna put it back the way it was and replace the intake tube gasket. Maybe I have a intake leak.

[2006rubicon]

Well that didn't work. Guess I'll change it back. I looked at the gasket on the intake tube I had to take off to get the Fairbanks mag off. I reused the gasket.

Round 57.4 I'm gonna put it back the way it was and replace the intake tube gasket. Maybe I have a intake leak.

Either that or the timing is still really retarded and you are a tooth off like I was, but in the other direction. When my mag was rotated down to where it was hitting the crankcase like yours is now I was super advanced... That would also explain why yours is easy to start, the plugs are firing way after TDC and you aren't fighting against the power stroke yet.

[Papee]

Well, I took it apart this evening, it's been way to hot to work on it. 105* today. I found that the intake tube that I had to take off to get the Fairbanks off was leaking at the gasket. That was the cause of the hard starting and rough idle. I got it all back together but it's to late to fire it up.

[Papee]

Finally!

After hours of working on this, I got it going. First was the vacuum leak on the intake tube I had to remove to get the Fairbanks off then realigning and more cussing then more realigning of the mag I still do not know what it was for sure. I did everything the same way I have done it every other time I went by the book. EXCEPT, this time I cleaned the plugs, two of them were wet.

I'll make a post later to clean this whole thing up for others that may have the same problem in the future.

[Duane Scarborough]

Yay !!!

I'm glad that you finally got it working again.

Don't know if the wet plugs were the problem or not, but it didn't help, I'm sure.

I can't count the number of times I've done something the same way (as far as I could tell anyway), and it took several tries before it worked.

Duane

P.S. My Daddy's best explanation of this was: "You just weren't holding your mouth right."

[Papee]

I'll keep adding to this post as I have time to get all the info and pics up.

First thing to do is take the cover off where the tach goes into the motor. This will allow you to see the timing marks on your Mag and cam gear. I took all my plugs out and rotated the motor until the number one piston is up, this will happen two times per cycle, once on the intake stroke and once on the exhaust.

When the number one piston is up and on the intake stroke you will see a "V" on the cam gear, mine has yellow paint on it. (There is also a "0" mark on the cam gear, not sure what that is) The V mark should be aligned with a dot on your Mag gear, it's just a little dot on one of the teeth.

This is the position you want to keep the motor in while replacing the Mag.

You can now remove the Mag. If you have a Fairbanks Mag you will bee to take off the Intake tube at the back of the mag. Next you will need to take off the Mag gear to place on your new magneto, there is a clip you have to take off to get the gear off.

After you have the gear on your new mag put a spark plug wire in the number 1 spot on your mag, there should be a "1" marked on your mag. Hold the end of the spark plug wire about 1/4" from the mag casing and turn the mag gear clockwise until you see a spark. When you see the spark then turn the gear CCW just a bit until you feel the magnet old it in place. You are now ready to install your mag.

You will have to get two new nuts and bolts to make the Slick mag work with the tabs included with the Mag. Tighten the mag down just enough that you can still rotate the mag for timing. You can use a multimeter on the "p" terminal on the continuity setting and turn the mag slightly until it reads open showing the points are in the open position. This should get you pretty close.

Spark Plug and cyl locations:



Firing order is 1-4-2-3

If you look at your new mag you will see a number 1 beside one of the contacts on the cap. Here is the position of the spark plug wires on the cap. Your orientation or position of your mag my be different.



Be sure not to turn you mag too far, the Slick Mag allows you to turn quite a ways from one way to the opposite. When you have it running the sweet spot is only about 2" of rotation total.

[2006rubicon]

That sounds beautiful! Glad it finally started behaving the way it's supposed to for a change! Now I wonder if you could fabricate a plexiglass governor hole cover...that way when it's crappy out and you can't go out and play you can always watch those little twirly gears in there, now that'd be COOL!

[Duane Scarborough]

That sounds beautiful! Glad it finally started behaving the way it's supposed to for a change! Now I wonder if you could fabricate a plexiglass governor hole cover...that way when it's crappy out and you can't go out and play you can always watch those little twirly gears in there, now that'd be COOL!

I like the plexiglas cover idea. With blinking LED lights inside. Oooh....

A different color for each cylinder.

Duane

[Papee]

You guys have a slightly different view towards that whirlygig, myself, I wouldn't care if I ever had to look at it again after taking it in and out about a dozen times. Mine is covered and forgotten hopefully.

[Duane Scarborough]

Papee,

Oh, so maybe Neon Spark Plug Wires would better suit you?

http://www.trixters-racing.com/neon.htm

Just kidding.

BTW, the alternating visual on their website is bogus. A Harley has a "wasted spark" ignition. Both plugs fire together! (Even when one is not needed).

Duane

[buster]

Papee,

Do you remember a while back when Duane and I was trying to figure out what color to paint our 084 engines? He came up with what he called "STEALTH BLACK", and foolish me, I thought he was trying to make the engine less noticable. I even thought it was a good idea, and I painted mine that color also

Now it looks like he wants you to put a flashing light show on your airboat?? What gives?

Dave

[Papee]

I see what you're getting at Buster, next it will be tinfoil hats. I know he plays them down but we both know how he works.

[Papee]

Well I finally had a chance to get the boat out on the river today. It was a little touch and go at first, it wouldn't spin up. I don't know if the flat was stuck or what but I left off the gas and hit it again and it started running better. I ran it for a few miles then stopped and adjusted the mag. It now runs better than it ever did, not just a little, quite a bit better. I gained 500 rpm. The river is a bit low right now so I didn't have much chance to run it all out for any distance, too many rocks sticking out now. The river is lower than it has been in years right now.

[Duane Scarborough]

Papee,

I'm glad to hear that you're not only back in operation, but it's also running even better than before.

With us removing the OE flywheel, and housing, it's almost impossible to judge true ignition timing. We no longer have a reference for a timing light. Trial and error works, but it's just that. A lot of trial and error before you find the sweet spot. Sounds like you've found the sweet spot.

That's good for you, but there has to be a better way. I'll start looking into it.

Duane

[Duane Scarborough]

Papee,

I've sent an e-mail to Les Smoot, who flies a fuel injected 4A084 powered airplane. He designed his own fuel injection system. I bet he knows an easy way to get the ignition timing right. I'll let you know.

Duane

[Papee]

Updating this thread for Nick(eskimoboy)

Here are two photos of the slick mag on my motor. The the mag is labeled as the plug wires are attached. Take notice that my mag is almost flat/ level. This may not be the same on your boat but should be close. This is where mine runs and starts best. The number one cyl is on the bottom right.

Not to confuse thing but there is not much information on this that I've found, the firing order depends on which way you believe the mag to turn. If you belief is that the mag turns CW the order would be 1-4-2-3 and if your information tells you the it runs CC it would be 1-3-2-4. I'm not sure if this information mixup is because the slick mag turns one way and the Fairbanks, the other turns the opposite.

Anyhwo...

I couldn't get a good photo because the mag fits is so close but here's what I have.

This is a top view showing the orientation of the magneto.

The photos will get bigger if you click them.



Here is a shot of where the number 1 is located.
The number one clyl is marked with a 1 beside the hole.



Is this is the correct cylinder numbering.



Here is a photo of where the cyl markings are on the motor, this is number 3 marked with a yellow circle.

Attachment 883


Notes:
Take note that the engine photo is taken from the rope start pulley end and not from the back as you may be looking at it.

When you are trying to get your motor running always check to see that your plugs are not fouled after trying it.

Be careful when moving or turning you slick mag, these mags have no stop and will turn a bunch moving it past the number one position.

If you have concerns about where your mag is located, mark it then pull it and see if your timing marks on the mag and cam gear are lined up.

Again, before trying each time be sure your plugs are dry. I had mine right a few times and moved on because my plugs were fouled causing it not to start even though I had the right rotation.

[eskimoboy]

Hi Papee this is me and my son Aaron

[Papee]

From the beginning:

With your magneto off the engine, take all the wires off but the number one.

put the wire end close to the case of the mad so you can see the spark.

Rotate the mag until you see the spark, once you see the spark rotate the gear backwards about 1/4 turn and keep this position while you install the magneto.

Before you install the magneto, be sure that your motor is at the top of the compression stroke. On my engine the cam gear had a (v) mark in that position. If it's 180 out or in the exhaust stroke mine has a (0) mark.

Put the wires on according to the above photos and as long as you are getting fuel it will start.


The only exception to this is if the magneto gear was put on 180* out. If this is the case it's time to start over.

[eskimoboy]

Papee at top dead center the cam gear is marked with a V and so is the mag gear