2-stroke engine start

[Alain G]

As ignition I have this:



If I say no bullshit we can not pay the advance?

I do have a floating ring which is connected to a punch which aims to always have the same level of fuel in the fuel

When I put gasoline in the room it is added to 2% oil.

OK, it is a fleet and needle!

The advance of the ignition is done by the flat head screw on the small rocker of the contact tip, if you have not disassembled it, there should not be any problem, a small folded very soft emery paper in two that you slide between the points when they are closed should assure you of the good functioning!

If you dismantled it I suggest you bring the engine to a repairer to have it recalibrated and it will tell you in no time the problem before you make an irreversible blunder!

[Alain G]

For close-ups here:





Sorry for the framing but my device doesn't have a practical screen.

There is indeed a small adjusting screw.
For me (and maybe wrong) this screw to make sure that the "coal" constantly touches the tree in the center.
Besides, at the beginning the coal did not touch all the time, I had concluded that that was why there was no spark.

No should not touch!

Oxidation is done on the contacts which no longer gives fire, it is then a question of doing as I say in my previous post!

Bring the engine to a repairman because if the advance is not well adjusted you will damage the engine, ditto for the carburetion which is very sharp on a 2 stroke to avoid seizure!

[Pascal HA PHAM]

hum ...

in the order of appearance :
the "breaker" is the part which rocks, on one side it is in contact with the cam of the central shaft but must not be in contact all the time (on one turn) .... on the other side from the same breaker there is a contact grain which breaks the current with the fixed contact grain of the small fixed and adjustable plate because it is tightened by the screw.

Well I take my explanatory breath:
on a portion of a tower you must note that the 2 grains touch each other and on the other portion of a tower that these grains remain distant / apart (the right dose is approximately 3 to 4 tenths of a mm, which would correspond to a few millimeters in advance on this type of engine before top dead center) if it is too far apart you are too far ahead and if it is not far enough apart you do not have enough lead or even no spark at all if the grains remain in contact.

Here is a test of methodology ... from a distance it is not easy!

Also take very fine sandpaper (600) that you pass between the grains to slightly scratch them (you put the paper when the grains are spread ... you turn the motor so that the grains close on the fine abrasive paper and you yank it out .... repeat the operation several times in one direction then in the other ....

amen!


So much for the ignition! I do not think that the condenser (small cylinder with the central wire which goes out) is in question because your engine seems in relatively good condition: but also continues to clean and re-clean the gasoline supply circuit from the carburetor.

hopefully it will all work out soon!
I cross my fingers (tighten the fixed grain support screw as well when the spacing seems good and the grains clean).

NB: to give you confidence it is like that that I regulate one by one, the 3 cylinders of my 500 kawa H1 with breaker (it dates from the 70s), I refine obviously afterwards by checking with the comparator the value in mm of my advance before top dead center (manufacturer's value).
No major problem otherwise.
A+

[aerialcastor]

I understood that on the grain side it had to move away at some point.

The problem is that right now it deviates rather by 1mm, and that if I reduce the spacing on the other side it does not touch permanently.
The coal must be too used, but I cannot find a spare part on the internet, which leads me to think that this type of wear is not very frequent.

The engine always has the same symptom, it starts a few seconds and chokes.

Okay, stop for tonight, it's high time to prepare the aperitif ...

[aerialcastor]

on a portion of a tower you must note that the 2 grains touch each other and on the other portion of a tower that these grains remain distant / apart (the right dose is approximately 3 to 4 tenths of a mm, which would correspond to a few millimeters in advance on this type of engine before top dead center) if it is too far apart you are too far ahead and if it is not far enough apart you do not have enough lead or even no spark at all if the grains remain in contact.

Well, that was it, the spacing of the grains is too important.

Thank you very much because I would never have found it alone.

[chatelot16]

on this kind of motor the advance is not directly adjustable: it is the adjustment of the distance which determines the advance

if you have the engine documentation, or if someone can give you the number, just set the correct spacing to have the correct lead

when I have no data, I pass a tool through the spark plug hole to spot the pmh and draw a benchmark somewhere

and then I connect an ohm meter on the breaker to detect the ignition point (on the flywheel magnetic ignition you have to disconnect the ignition coil of the flywheel which is in parallel on the breaker

it lets you see if the ignition advance is reasonable

here too we should know the advance planned for this engine: but when I see an angle of advance comparable to the other engine that I checked it

another problem, the position of the magnet of the magnetic flywheel: if it is mounted in any way (key forgotten) the maximum current is not produced at the opening of the breaker: it makes a too weak spark and it does not work not

for difficult starting see also the state of the piston: I saw the engine with part of the skirt of the broken piston: it sabotages the operation of transfers it starts a little with the starter but it never works properly

the engine must suck straight through the carburetor: if it does not suck there is a problem in the engine

[dedeleco]

Fun vocabulary:

For me (and maybe wrong) this screw to make sure that the "coal" constantly touches the tree in the center.
Besides, at the beginning the coal did not touch all the time, I had concluded that that was why there was no spark.

Well, that was it, the spacing of the grains is too important.

The grains, we tend to call them platinized screws of the breaker, to resist sparks of contact breakage which trigger by induction in the coil, the spark in the spark plug, when the piston is in the right place (chamber close to the minimum of volume with the piston at the top which compresses) to trigger the explosion in the piston !! Coal is probably the cam on the camshaft !!
What is essential is not the distance of the contacts but the moment when they separate to make the spark plug.
The contact between these platinum-coated 'grains' of the breaker must be good (very clean and flat) to allow the current to pass through the primary of the coil and rupture, when the ignition is suddenly cut off, triggers the spark !!
Knowing this, we adjust approximately and try slight changes in position until the best engine performance under load.
I think it is better to know the principles of internal combustion engines and their ignition, to find your way and make the right choices and save time by avoiding mistakes.
See google:
the image of the 2 stroke engine movement, sparkles a little ahead of the piston at the top:
http://fr.wikipedia.org/wiki/Moteur_%C3%A0_explosion
http://fr.wikipedia.org/wiki/Cycle_%C3%A0_deux_temps
http://www.tract-old-engines.com/2tps.html
http://www.motoculture-jardin.com/moteur-2t.html
http://www.mobcustom.com/229-fonctionne ... ur-2-temps
http://www.kh.refer.org/cours_en_lignes ... rs15-1.htm
http://www.toutsurlamoto.com/lemoteur.htm
and the breaker, coil and spark plug system:
http://bielles.free.fr/bielles-mecanique/allumage.html
basic course:
http://site.voila.fr/FASTOCHE/Self_indu ... uction.htm
http://philippe.boursin.perso.sfr.fr/pdgallum.htm
http://daxtoulon.xooit.fr/t1370-L-allum ... regler.htm
http://philippe.boursin.perso.sfr.fr/bo ... dgmagn.htm
http://fr.wikipedia.org/wiki/Histoire_d ... icit%C3%A9
http://membres.multimania.fr/electrotec ... ectrom.htm

[Flytox]

Hello aerialcastor

This ignition should work like those of old mob and Solex.
The spacing of the contacts does not have a very tight tolerance (type 0.3 to 07 mm). What is important is to put the right lead by adjusting this famous contact (platinum screws).

The contacts must move away at the exact moment or the fixed mark (on a casing) falls opposite the (mobile) mark on the magnetic flywheel. You must identify exactly these 2 benchmarks. There is certainly no adjustable advance since your steering wheel is keyed, the cam that lifts your latch will be eternally in the same place relative to the top dead center.

The best, as Chatelot16 tells you, is to do this locating a voltmeter or with a lamp in series on the contact.

[Flytox]

Oooups dedeleco got ahead of me!

Well the links

[dedeleco]

Oh no, the magnificent drawing is much better and clearer !!!!!
There is no photo !!!!