2002 DX150TLRA Ignition -Timing - Number of sparks per cylinder

[captainj]

Should there be one or two sparks per revolution?
I have a ES328 Tach that clips onto the spark plug wire. When clipped to #1 and #2 cylinders I get 2 sparks per cylinder and the rest of the cylinders are getting 1 spark per revolution.
The timing on #1 cylinder is 3 ATDC all other cylinders are around 7-8 ATDC
Whats going on? Could it be the pulser trigger coils?
I have been dealing with unstable idle speed.
Thanks for your help

[captainj]

Anybody. Please help
Rodbolt you out there.
Thanks

[99yam40]

does the timing light also show the 2 sparks on #1 and #2.

i am thinking that tach is just picking up stray impulses maybe. not the best to use on these motors with so many plugs going off

[boscoe99]

Two strokes normally have one spark per cycle. Each time the piston is near top dead center a capacitor discharges current into the ignition coil. The spark plug fires when the voltage rises to the point that the spark can jump across the spark plug leads.

I am not understanding seeing two separate flashes from a timing light, at a rate of 10 times a second, each time the plug fires. 600 RPM divided by 60 seconds per minute.

[captainj]

I just got the tach so I am not sure it is working properly. Maybe be random signals. But something is going on. Idle speed will speed up a little bit then it will slow down. I can not tell if there is 2 sparks with the timing light. But timing is another issue #1 is at 3 ADTC and the other cylinders or at 7-8 ATDC what is causing that?
What would be a good diagnostic tach?

[99yam40]

If 1 or 2 cylinders flash at twice faster rate, I think I could tell maybe.

some tachs even have RPM built into them monitoring the spark rate so you could see it that way too

OP I have no idea how one or 2 cylinders could have timing different

[boscoe99]

Timing is normally based on the number one cylinder. What prompted you to check timing on the other cylinders?

Have you done a sync and link on the motor?

[captainj]

Link and sync done. New LP fuel pumps, New HP fuel pump and Filter, New O2 Sensor, Injectors cleaned and flow tested, CTS replaced, CDI output peak voltage 200v, Charge coil 240v, Pulser coil output voltage 17v @ 1500 Rpm. The manual specs for pulser coil is 16v @ 1500 rpm so I am very close to the min. on this one. Maybe the problem?
No codes on light.
I checked the other cylinders with the timing light to see if they were the same thought that might be a problem if the were not the same. I feel like that is a problem if the timing is not the same on all the cylinders. Not sure if the pulser coil is the problem with the timing, and possibly the random spark if that is even possible if tach is correct.
Thanks for the help

[fairdeal]

Two strokes normally have one spark per cycle.

I did not think all 2 stroke were waist spark motors, firing on every stroke.

Interesting;

we say 2 stroke vs 4 stroke motors.

But we also say "2 cycle" and "4 cycle" for those same motor types.

I've been hearing, and using, the terms for 50 years but never thought about the oddity of those phrases:

They only make sense as "shorthand" for "2 strokes per power cycle" and "4 strokes per power cycle"

I wonder how such sloppy terminology came about?

[boscoe99]

Interesting;

we say 2 stroke vs 4 stroke motors.

But we also say "2 cycle" and "4 cycle" for those same motor types.

I've been hearing, and using, the terms for 50 years but never thought about the oddity of those phrases:

They only make sense as "shorthand" for "2 strokes per power cycle" and "4 strokes per power cycle"

I wonder how such sloppy terminology came about?

Two cycle equals two strokes. One stroke down (power and compression) and one stroke up (exhaust and intake) per firing event.

Four cycle equals four strokes. One stroke down for intake, one stroke up for compression, one stroke down for power, one stroke up for exhaust.

But yes, the English (maybe all) languages has been butchered. Every thing one needs to know about language was explained by Gallagher.

[boscoe99]

Link and sync done. New LP fuel pumps, New HP fuel pump and Filter, New O2 Sensor, Injectors cleaned and flow tested, CTS replaced, CDI output peak voltage 200v, Charge coil 240v, Pulser coil output voltage 17v @ 1500 Rpm. The manual specs for pulser coil is 16v @ 1500 rpm so I am very close to the min. on this one. Maybe the problem?
No codes on light.
I checked the other cylinders with the timing light to see if they were the same thought that might be a problem if the were not the same. I feel like that is a problem if the timing is not the same on all the cylinders. Not sure if the pulser coil is the problem with the timing, and possibly the random spark if that is even possible if tach is correct.
Thanks for the help

There are six pulser coils on your model. All five out of wack? I would not think so.

[captainj]

Why is #1 at 3 ATDC and the other 5 cylinders are at 7 ATDC? Is it possible the ecm is trying to adjust idle speed due the timing being different causing the idle speed to vary back and forth. I don't have access to another engine to check the timing on. If its not the pulser coils what else could it be? I just don't think this is right.
Thanks

[99yam40]

only thing I can offer is to check timing again.

timing will change on my C40 motor from start up to warmed up.

maybe you happened to look before it was warmed up completely on #1

[cpostis]

Why is #1 at 3 ATDC and the other 5 cylinders are at 7 ATDC? Is it possible the ecm is trying to adjust idle speed due the timing being different causing the idle speed to vary back and forth. I don't have access to another engine to check the timing on. If its not the pulser coils what else could it be? I just don't think this is right.
Thanks

I never heard of checking the ignition timing on other than #1 cylinder, so I don't know if difference in timing between #1 and others is relevant. Why are you checking timing on the other cylinders. Where did you hear of such a check, and what would the purpose be?

Although #1 cylinder is the same bore as the others (fact), the piston diameter is smaller than the others (fact). #1 cylinder has the port that sends gasses to the O2 sensor (fact). Does this have anything to do with the variance in timing? For that matter, can anyone tell me the engineering reason for the smaller diameter piston?

I think the ECU measures/controls timing only on the # 1 cylinder, and thus the timing on the other cylinders is based on the design of the crank in respect to #1 cylinder timing? Can someone tell me different, or elaborate?

As far as your two sparks per revolution goes on cylinder #1 and 2, I know on my 2001 SX150 TXRZ there is one spark per revolution on cylinder # 1. I added a tach/hour/service meter to mine that corroborates this along with my console Yamaha tach. The meter I bought is selectable to the # of sparks per revolution. You can check any cylinder rpm, and thus spark count on any cylinder you wish by simply wrapping the inductive pick lead on the lead you wish. The meter is self powered, and counts revolutions by inductive pick up via a lead wrapped around the spark plug lead. I bought mine for $40 and just found the same meter on Amazon for $13.99.
Here's a link.
https://www.amazon.com/Docooler-Tach...our+tachometer

I'll add a vid showing the tach/hour/service meter in action to another post (if I can find it).

[cpostis]

QUOTE=captainj;122896]I just got the tach so I am not sure it is working properly. Maybe be random signals. But something is going on. Idle speed will speed up a little bit then it will slow down. I can not tell if there is 2 sparks with the timing light. But timing is another issue #1 is at 3 ADTC and the other cylinders or at 7-8 ATDC what is causing that?
What would be a good diagnostic tach?[/QUOTE]
Here's the vid I said I'd post. The tach/hour/service meter is at the very end of the vid.
https://www.facebook.com/chuck.posti...4531213370606/

https://www.amazon.com/Docooler-Tach...our+tachometer