Timing Check

[ShoerFast]

check out the ignition trak tool, gap is pressurized during testing

046

As it's hard to see how that tester work, the plastic covers has glare. It would be a take off of another gap bridging test tool,,,,,, all the testers out there are all most as accrute as a paper clip and a lenght of string.

Pashchen's voltage law, from back in the 1800's . It's simple, it takes about 13 Kv to bridge a 5/32 gap,,,,, more under pressure V= f( pd ),,,,,IOW using a paper clip stuffed in the spark plug boot and you can pull the paper clip away from the cyl (ground), with the lenth of string .a it throws a good blue spark at least 3/8 of an inch, it should fire under pressure, or bridge a spark gap of .025 of an inch.

But as this tread started, this saw had a questionable primary side, not secondary.

Kevin

 

[Lakeside53]

046

As it's hard to see how that tester work, the plastic covers has glare. It would be a take off of another gap bridging test tool,,,,,, all the testers out there are all most as accrute as a paper clip and a lenght of string.

Pashchen's voltage law, from back in the 1800's . It's simple, it takes about 13 Kv to bridge a 5/32 gap,,,,, more under pressure V= f( pd ),,,,,IOW using a paper clip stuffed in the spark plug boot and you can pull the paper clip away from the cyl (ground), with the lenth of string .a it throws a good blue spark at least 3/8 of an inch, it should fire under pressure, or bridge a spark gap of .025 of an inch.

But as this tread started, this saw had a questionable primary side, not secondary.

Kevin

Be careful with the paper clip method in saws - you can get too much gap. I've seen more than one coil fail because it was "open circuited", generated a high voltage and broke down internally. The coils have internal spark gaps to help in this situation, but they can still fail. Was it winding breakdown or electronic trigger failure? don't know... That's why using a ground-off plug (about a 1/4 inch spark throw) or a 'pre-gapped" test jig is the best practice. Same goes for pulling a saw over with the plug out - make sure the ignition switch is off.

 

[ShoerFast]

Be careful with the paper clip method in saws - you can get too much gap. I've seen more than one coil fail because it was "open circuited", generated a high voltage and broke down internally. The coils have internal spark gaps to help in this situation, but they can still fail. Was it winding breakdown or electronic trigger failure? don't know... That's why using a ground-off plug (about a 1/4 inch spark throw) or a 'pre-gapped" test jig is the best practice. Same goes for pulling a saw over with the plug out - make sure the ignition switch is off.

Lakeside53

You make a good point on something that sould be done when the saw is still new and on warrenty!

As I'm sure thats part of the long term integrity.

If we were thinking, a bar adjusting wrench could be made to hold a plug with the lead attached, snaping off the groung electrode and sliding the wrench under the covers next to the cylinder would make a very handy tester.

Kevin

 

[Lakeside53]

Lakeside53

You make a good point on something that sould be done when the saw is still new and on warrenty!

As I'm sure thats part of the long term integrity.

If we were thinking, a bar adjusting wrench could be made to hold a plug with the lead attached, snaping off the groung electrode and sliding the wrench under the covers next to the cylinder would make a very handy tester.

Kevin

It would...

I just solder a 8 inch test lead on the outer case of the plug and an aligator clip on the end - and clip it to the cylinder fins.

 

[Simonizer]

Got 5 seconds. That doesn't corespond with my findings though. I haven't tested that specific coil though. I will check one tonight.

Fred

Have you checked yet? When you found out I was not BS'ing, you disappeared. Figures. If my numbers had been wrong you would have been all over me Fred. I verified it again today, 23 degrees BTDC with Snap-On digital timing light.

 

[046]

that's what I use too, Snap-on digital timing light.

here's a pic of ignition trak showing plastic piston, which compresses air around gap.

 

[Simonizer]

that's what I use too, Snap-on digital timing light.

here's a pic of ignition trak showing plastic piston, which compresses air around gap.

Looks like an easy thing to build 046. It would be nice with a regulator hooked up to shop air supply. I always like gauges to read in units rather than red, yellow, green etc, but it is a cool idea nevertheless, thanks.

 

[Simonizer]

Have you checked yet? When you found out I was not BS'ing, you disappeared. Figures. If my numbers had been wrong you would have been all over me Fred. I verified it again today, 23 degrees BTDC with Snap-On digital timing light.

It sure gets quiet in here sometimes. Can't you guys type and backpeddle at the same time?

 

[RES]

How does that thing work?

1. You connect one clip to the sparkplug wire
2. You connect the second one to ground.
3. You pump up the little piston.
4. You then view the spark thru the window

You view the spark as you are cranking the piston. If it sparks the system is OK.
Am I correct?

 

[ShoerFast]

How does that thing work?

1. You connect one clip to the sparkplug wire
2. You connect the second one to ground.
3. You pump up the little piston.
4. You then view the spark thru the window

You view the spark as you are cranking the piston. If it sparks the system is OK.
Am I correct?

Yes and no,,,,,

That looks like the way you would use that thing-a-ma-jig, but it would have nothing to do with if the system worked,,,,, it looks more like you would be holding up a dollar for a dime.

Last I checked, you can buy a new plug for a couple of bucks, with $75. dollar an hour shop rates, or the value of your time, why would you only test the final portion of the secondary side of the ing.?

The pressure that thing tested at would need to be astronomical to simulate the inside of the combustion chamber of a running engine,,,,,as pressure dose make it harder to fire the gap, heat is another source of excessive resistance.

The only real way to test the total ing. system is with an oscilloscope, as there is a ton of information that it can give you.

Or twist in a new plug?

Kevin

 

[ShoerFast]

It sure gets quiet in here sometimes. Can't you guys type and backpeddle at the same time?

Gloating that you know what the timing was? After so much time has passed! Who did you need to ask? Did you get there voice mail the first hour?

How about woop some of the engineer stuff up and explain how you determine optimal timing?

If you would enlighten us rednecks?

Kevin, the unenlightened

 

[Mr.]

Have you checked yet? When you found out I was not BS'ing, you disappeared. Figures. If my numbers had been wrong you would have been all over me Fred. I verified it again today, 23 degrees BTDC with Snap-On digital timing light.

Okay scooter sorry about the wait. I really am concerned it took you an hour to check the timing and if I forget about something like this because I get busy, I'm backpeddling.

Your figure is still slightly low, but I'm not going to spend all my time educating guys that state they need none.

I don't back peddle. If someone is right they are right and you are close enough to get credit.

Fred

 

[Simonizer]

Gloating that you know what the timing was? After so much time has passed! Who did you need to ask? Did you get there voice mail the first hour?

How about woop some of the engineer stuff up and explain how you determine optimal timing?

If you would enlighten us rednecks?

Kevin, the unenlightened

Perfect ignition timing promotes complete combustion. Ignition timing requirements vary with several factors, RPM, combustion chamber shape, flame-front velocity, etc. If a saw spends most of its life at 11500 RPM under load at full-throttle, a dyno is an excellent tool for getting right to the point. An exhaust gas analyzer is also useful. Short of this, a spark plug can tell you quite a bit. When I was racing RZ350's in the late 80's we used to do what was called a plug chop at high load and RPM.

 

[ShoerFast]

Perfect ignition timing promotes complete combustion. Ignition timing requirements vary with several factors, RPM, combustion chamber shape, flame-front velocity, etc. If a saw spends most of its life at 11500 RPM under load at full-throttle, a dyno is an excellent tool for getting right to the point. An exhaust gas analyzer is also useful. Short of this, a spark plug can tell you quite a bit. When I was racing RZ350's in the late 80's we used to do what was called a plug chop at high load and RPM.

Why Thank You !

Understand, I really just shoe horses.But,,,,

Leaving out a few very important issues, like the octane rating that could be purchased locally and the altitude that the engine will spend it's life at could be important. But not touching on a generalization of the compression ratio and engine designed working pressure seems lacking to your total abilities?

Considering that the chamber shape could include the squish band to some degree, not timing the spark to be there before the cylinder concentrates the fuel around the plug, would be the same as not taking the heat range of the plug into effect, as fuel will either lite by the hot plug or the spark, most CC's are designed to hold burning, slowly expanding fuel around the plug before the cylinder reaches it's highest compression pressure, the very key to optimum timing.

To start with the statement that "Perfect ignition timing promotes complete combustion." sounds a little out of the book, as pre-ingition will aid in complete combustion. Wouldn't peak performance indicate complete combustion?

As for the 4 gas analyzer, seems to give you a ballpark figure for setting air-fuel ratios, 2 cycle oils tend to not burn as completely at hi rpm low load / pressure settings, whacking your HC and CO readings. And have you noticed how O2 Just seems to fallow stoichiometric? So whats left, CO2? thats going to set your timing?
I would much rather have a good fast scope monitoring the secondary voltage collapse, as cylinder pressure is resistance, you can Tailor the spark to the CC design , engines firing pressure and fuel quality.

For a Mechanic, I would give you a "B" but as world class engineer, a "D"

Kevin

I would like to know more about "plug-chop"? this is new for me!

 

[046]

not everyone has a four gas analyzer. here's another tool that I've used for years.

basically correct fuel to air ratio occurs somewhere aprox. 16:1 ratio. if one could see the color of the flame during combustion. one can tell with accuracy how complete combution proccess is actually occuring.

it's the exact same as looking at flame on a gas stove or heater. when you see blue almost total combustion is occuring. when you see yellow or orange incomplete combustion is occuring resulting in higher co production.

the device is called a Color Tune. it's a spark plug looking tool with a window that allows you to see into combustion chamber. simply see what color flame is being produced and adjust accordingly.

it's extremely valuable tuning multi cylinders, when you need to see what each idividual cylinder is doing. a gas analyser can only tell what total output is. Used it tuning mult-carb V-12 Jaguars

gotta dig thru my HUGE snapon toolbox to find.

 

[ShoerFast]

not everyone has a four gas analyzer. here's another tool that I've used for years.

basically correct fuel to air ratio occurs somewhere aprox. 16:1 ratio. if one could see the color of the flame during combustion. one can tell with accuracy how complete combution proccess is actually occuring.

it's the exact same as looking at flame on a gas stove or heater. when you see blue almost total combustion is occuring. when you see yellow or orange incomplete combustion is occuring resulting in higher co production.

the device is called a Color Tune. it's a spark plug looking tool with a window that allows you to see into combustion chamber. simply see what color flame is being produced and adjust accordingly.

it's extremely valuable tuning multi cylinders, when you need to see what each idividual cylinder is doing. a gas analyser can only tell what total output is. Used it tuning mult-carb V-12 Jaguars

gotta dig thru my HUGE snapon toolbox to find.

046

Thats sounds like it would work very well, it's about the same as the data storage that NHRA allows. But they use a heat probe for each cylinder,, engines with blowers especialy tend to get less air the further back on the blower you get, and need to be jetted for that,,,, there nothing more then a 2 wire thermal-coupler, a pro for using heat probes, it's fast and easy to test,,,,, a con is that it's extremely load / pressure sensitive,,, iow, it needs a trend , like consistant power. Very ideal for AC and boats.

If you have a heat probe of any kind, set in the exhaust flow and hook it up the a DVM, just bearly tweek the H jet and you'll see it as voltage.

Kevin

 

[046]

ok, here's a pic of Color tune, had to unearth it from my guages drawer. all sorts of Snapon compression, fuel injection, vacum, oil pressure, etc. etc...

 

[ShoerFast]

ok, here's a pic of Color tune, had to unearth it from my guages drawer. all sorts of Snapon compression, fuel injection, vacum, oil pressure, etc. etc...

Thats too cool,

Snappy also makes a lite sensing prob in the shape of a glow plug for diesel timing,,,,,,, twisting it in place of a glow plug of a run warm diesel , it would trip a strobe when the cylinder fired so you could time the injector pump.

Kevin