Stalled, Stopped...& Started

[Vision]

Today I was 25min into a routine 45min ride. Approaching a red light on an incline I was drifting to a stop. When the light turned green I gave it a little throttle and the engine quit and wouldn't restart. After pushing it around the corner and taking a moment it wouldn't restart. I tested the lights and they worked. About 5 minutes after the stall and 10 restarts it started and it didn't stall on the way home.

Any thoughts on what happened? I recently changed the oil and forgot the techron in the gas so am suspecting a carb problem.

[Stig / Major Tom]

Might try an Iridium NGK.....gives a healthier idle speed.
But plug probably not the root of your problem....unless really old.
Failing coils get hot...quit...work again after cooling down some.
One other thought is ...improper valve clearances.
Modern fuels rarely give problems....unless buying from a guy on a dirt road selling from Pepsi bottles in a 3rd world country.
A healthy scoot doesn't need magic additives.
Stig

[scooterfan]

Chances are very good that the CDI is dying. My Agility did the same a couple of times at about 9300 kms,  and replacing the CDI solved the problem.

[Vision]

Stig:

It has a new Iridium NGK as of a few months.

What does "failing coils" mean? CDI? Stator?

Rode it this morning and had no problems. Yesterday was hot, around 95f.


Scooterfan:

Is there a way to diagnose a CDI problem?

What CDI to buy? Stay away from "high performance" CDI's?

[TBR125]

Possibly a bystarter issue. I have no idea though as I removed mine a long time ago.

[scooterfan]

Scooterfan:

Is there a way to diagnose a CDI problem?

What CDI to buy? Stay away from "high performance" CDI's?

I stripped and checked everything when I experienced a similar problem- including carburetor, fuel lines, spark plug, coil, plug wire, fuses, and wiring.
The last thing I did was to replace the CDI, and the problem was solved.

If I remember correctly I saw a video on Youtube which shows how to test a DC CDI but I didnt test mine - I just replaced the original one.

[Vision]

Following up on this...I failed to add in the original post that that afternoon was hot, like 95f or so.

I recently adjusted the valves. Intake was .005 which it was left at and I don't know how wide the exhaust was but it was wider than .006. Exhaust was adjusted to .005 and the performance has improved remarkably. There was a tapping sound which is gone.

Any different in performance between running the intake at .005 and exhaust .005 rather than .004/.005? Didn't find this answer by search. Even if the change would be academic what should a tighter intake produce?    

[CROSSBOLT]

Tighter means it stays open longer by some small number of degrees (not many!). The gap is widest when cold and decreases with heat. Set when cold to spec means the gap won't disappear when normal engine temp is reached. You already found out whatcha get when it is too wide!

[Stig / Major Tom]

Following up on this...I failed to add in the original post that that afternoon was hot, like 95f or so.

I recently adjusted the valves. Intake was .005 which it was left at and I don't know how wide the exhaust was but it was wider than .006. Exhaust was adjusted to .005 and the performance has improved remarkably. There was a tapping sound which is gone.

Any different in performance between running the intake at .005 and exhaust .005 rather than .004/.005? Didn't find this answer by search. Even if the change would be academic what should a tighter intake produce?   

.oo4 & .oo5 both likely fall within the specified +/- variance of the specs.
There should be a sticker, perhaps under the seat,  with this kind of info...& plug gap, etc.
Stig