Lets talk about timing...
 

What do you guys think are pros and cons of advancing timing as compared to retarding it? I know my engine starts easier when I have the timing set to the recommended 28 degress. I've retarded it somewhat too and it ran ok,but its hard to start. I'm kinda afraid to advance it because I dont want any pre-detentation or anything,yet its hard to start if I retard it. I just started testing this new homelite 54cc. I'm also thinking if I advance it too much it will have a very rough idle,thus having a tendency to virbrate the motor from the mounts(I already have one gash in my knee from that). I also know that you tend to get more rpms and power from advancing the timing,but in my case I'm gonna have more then enough power,so I'd rather have a smoother running engine that also starts easy....so maybe I'd be better retarding it??? I'm still in the early process of testing,so I havent played around too much on this 54cc engine,but its quite a monster and I hate messing with it too much for safety reasons,and I plan on getting my 22cc stihl running in the next couple days and really putting it through some testing.

Lets hear some of your timing knowlegde,advice,and imput.....or even questions.

RE: Lets talk about timing...
 

From a retarded setting, increase timimg little by little, until you find best rpm. that is the setting you will want to run.
If you advance further, rpm will remain the same, but the engine will start to run rough, and plug tuning (judging) will become confusing. There will appear a burnt ring at the end of the central electrode. Retard ignition again until this ring disappears.

RE: Lets talk about timing...
 

Jester, I do not know what ignition you are trying to adjust the timing on. Some flywheel mags have a advance curve built in, and seems to be perfect for best idle, yet revs up real good also. The engine I am talking about is a Mac MB290. You will see in photo below, I found this out with a timming light. I cannot wait untill they come up with a super light mag that will give good spark and weigh 1/10 th the weight. The rotor could be more flat and the coil could be thinner and hang in place a brake rotor. Come on guys...get to work and design one!!!! Capt,n

RE: Lets talk about timing...
 

This is the first time I have heard of reducing the the advance causing hard starts. It usually makes starting easier and smoother idling. All 2 stroke outboards have VERY retarded timing at start up. The cams are large and unmistakeable as both timing & carburator move to the full speed position.

RE: Lets talk about timing...
 

0 to 5 degrees makes for nice starting and idling, 28 to 30 makes best power with these little engines.

AV8TOR

RE: Lets talk about timing...
 

;)
You are right...I read somewhere that some brand of CD units retard the spark for starting more than others. Maybe his CD unit is retarding the spark too much! If he would post all the details...maybe we could figure it out! Capt,n;)

RE: Lets talk about timing...
 

Heres the Ignition I got....

http://www.syssaaircraft.com/gas_engine_ignitions.html


I believe it is an auto advancing model. I'm not exactly sure how that works or what it exactly it does. I did however spend more time playing and tuning last night and tried retarding the magnet more on the hub and it did seem to idle better and still started ok. My starting,which isnt terrible mind you......could have some to do with simple needle tuning too.

But yes,if someone could explain in detail this auto advancing feature on these ignitions,that would be great.

RE: Lets talk about timing...
 

You are right. It is a start/retarded. Like me in the morning.

Run advanced.
A person with a magnetic timing light, the type that closes around the spark plug wire, MAY>>MAY get enough signal thru the shielding to see the firing time.

If he can. Take the plug out and bring the piston to the top. That is TDC. Or 0 degrees of timing. Put a mark on the non-moving part of the engine as a reference point. Rotate the engine BACKWARD 90 degrees. Put another mark. That is 90 degrees BEFORE ..TDC. Rotate the motor 1/2 way back to TDC. Mark that point as 45 degrees before TDC.
Still with me ?
ALL timing light flashes HAVE TO OCCUR between 0 and about 38 degrees before TDC. No exceptions.

Rich

RE: Lets talk about timing...
 

Quote:
“A person with a magnetic timing light, the type that closes around the spark plug wire, MAY>>MAY get enough signal through the shielding to see the firing time.”


If the shielding wont let you pick up a signal, you might try clipping the whole plug wire with the plug connector off an old mag coil.
Then strip back a couple/three inches of insulation,fold that wire enough times on itself to fit the center post connector in the cap completely,and tightly.Secure with a wire tie.

Run a temporary ground wire from the lead shielding to the engine. Pop this “test jumper” on the spark plug.

You will now be able to pick up your signal. For testing purposes,on the ground only,of course.

Edit to add pics.

RE: Lets talk about timing...
 

You can use the older, non inductive timing lights too. Just put a paper clip under the spark plug boot while it's connected to the plug and hook it to the lead on the timing light. I used to do this often on cars at the distributor cap when number one spark plug was difficult to get at to unhook and install the timing light connector.

AV8TOR

RE: Lets talk about timing...
 

NOTE...Make sure you connect the jumper wire from metal to the engine. Make sure this is a good ground or some ignitions will get damaged. So use Caution. You cannot put a bare wire or paper clip under a metal cap/boot. It will just short out. Just make up a apapter that plugs into boot and has a way to clip on sparkplug tip. That will give you a inch or so of ushielded sparkplug lead. JUST MAKE SURE TO USE JUMPER TO COMPLETE GROUND TO ENGINE FORM METAL BRAID OR METAL CAP. I will make one and post photos. Good to have for testing various engines. Best Regards Capt,n;)

RE: Lets talk about timing...
 

A new unit SHOULD NOT need to be tested or modified.

HELL. These CDI units cost as much or more than a engine !!!!!!! send it back if in doubt.

I pay full price with perfect money. I want a perfect unit !!

Rich

RE: Lets talk about timing...
 

Do you somehow feel this statement was this not CLEAR or STRONG enough ?

“Run a temporary ground wire from the lead shielding to the engine”

I think Av8tor was talking about inserting the paper clip under the rubber boot
of the test jumper,NOT the metal electronic ignition cap.

Anyone handy enough (every one here…) to make this
adapter will understand this.

RE: Lets talk about timing...
 

I did not say testing ignitions...I use one ignition to TEST ENGINES Capt,n[X(]

RE: Lets talk about timing...
 

This is just for seeing the actual advancing of timing while running.
NO mods to ignition happening here.

RE: Lets talk about timing...
 

The "send it back" is for Jester. He should not have to readjust his carburator in any way with a new ignition system installed.

Send the CDI back.

Rich

RE: Lets talk about timing...
 

Jester...send that ignition back like Cyclops says, if you are sure the carburator is set right. It would be a waste to send ignition back though, only to find out later you may NOT have the carb set right and that was the problem! Capt,n[:-]

RE: Lets talk about timing...
 

I think there may be some confusion here....or maybe its me,lol. I dont think my ignition is faulty. I was simply doing some timing testing thinking that if I adjusted the magnet via my adjustable timing ring on my hug....it might make the engine run different and/or change the starting performance. The ignitions directions say to set it at 28 degrees which I did. I then kinda played around with it from there just to see if I could tell any differences. I thought maybe I did,but now after more testing...quite frankly I'm not sure. I must also keep in mind its cold out,and I dont have the throttle hooked up to a servo thus I cant adjust how much gas I'm giving it while starting it....I just have the idle screw set at a very slightly fast idle and am starting it from there. It starts after a bunch of flips in the cold,I just though maybe I could improve it. I thought perhaps playing with my timing might change things,but now I'm finding out that the ignition kinda adjusts itself which I still dont understand too well. I was just wonding if it would benifit me at all to vary from my 28 degrees. For this engine,I would prefer it to run super smooth and start nice more then trying to soak every bit of power from it as it will have plenty for the plane its likely going in. I want to keep it vibaration to a minimum.

So,basically what I'm gathering is its probly best to leave it at 28 degrees and the ignition will do the rest? Or what would you suggest I do to get it to run like I want? Hope this might clearify things a bit.....at least to me,lol. [8D]

RE: Lets talk about timing...
 

The carb settings have a lot to do with vibration at low speeds. Also the idle speed itself. To slow a idle sometimes makes it worse. The more time you get on a engine and it gets broke in real good it will also help the smooth running aspect! You can make a hand throttle with a Popsicle stick drilled for a small bolt. Bolt it to a "L" shaped piece of metal so it pivots at bolt. Have the bolt kinda snug but so you can pivot the stick. Attach the needed linkage to carb throttle lever. Now you got a hand throttle! Good Luck Capt,n

RE: Lets talk about timing...
 

I have the throttle hooked up to a nice little handle. I just cant keep it held at a certain spot while I flip the prop. Once its running I have control of it.

RE: Lets talk about timing...
 

Quote:
“Some flywheel mags have a advance curve built in, and seems to be perfect for best idle, yet revs up real good also. The engine I am talking about is a Mac MB290. You will see in photo below, I found this out with a timming light.“


Please give us an “estimate” of the total amount of advance movement (in degrees) that YOU actually witnessed on that Mac implement engine,using the pictured timing light.

Thanks.

RE: Lets talk about timing...
 

I did not have a degree wheel on it, but I had a mark on the flywheel and it moved about 1/4 inch to 3/8 of a inch. I had this mark lined up with metal edge of coil. This engine in blower on standard flywheel ignition, has one of the lowest idle speeds I have seen. I may make a short video that contains some various engines running. Capt,n

RE: Lets talk about timing...
 

Interesting.
Is this now commonplace on other new weedie/saw/blower, type engines?

Could anyone here provide an explanation,or maybe a link to a circuit diagram of how this may work?

RE: Lets talk about timing...
 

I think it on the Walbro carbuator site where I read about this type of advance. Or it may be under the mane that is on flywheel of your engine. Capt,n

RE: Lets talk about timing...
 

If you check the flywheel, there will be an US patent number on it.
Then go to USPTO.gov, and find out the whole chebang, wiring charts included.