moteur numero 1

[charles]

 
en effet!

[mitch83]

transition brutale, pas bon, car sur ouverture brutale du boisseau,

commences par descendre le clip sur l'aiguille, aiguille plus haute, je pense qu'il manque de l'essence. il n'est jamais bon de mettre le clip aux extrémités, si tu sens qu'il faut encore plus d'essence il faut voir le gicleur, c'est la même chose dans l'autre sens

[charles]

merci Mitch,
j'ai joué un peu avec l'aiguille, mais ça n'est pas ça encore.
je suis embété, j'ai 3-4 puits d'émulsion possible 8, 20,30,40, mais les gicleurs du puits 8 trous ne se montent pas sur les autres puits. (commande de gicleurs hexagonaux en cours)
ce que j'ai trouvé de mieux (moins pire en transition), c'est un ralenti 42/puits 40 trous, gicleur 120 (trop riche à tres haut regime me dit la gunson).
je vais reessayer en jouant avec l'aiguille, mais je galère.
j'ai essayé de suivre dans l'ordre le tuto http://kdx125.pagesperso-orange.fr/Page17.html, mais si j'essaie d'appauvrir en haut, la transition est de plus en plus pourrie.
à suivre

[Anna]

Ça ressemble de plus en plus à des conversations de motoristes‼️
J'aime bien ‼️
Et bravo 👏

[mitch83]

si tu es vraiment trop riche à plaine ouverture c'est le gicleur qui doit être trop gros puisque l'aiguille ne sert plus à rien quand le boisseau ouvert en grand.

[charles]

En effet Mitch
Je suis descendu jusqu'à 108 en principal.
Quand ça cale à l'ouverture brutale, la Gunson semble m'indiquer que je suis trop riche ( c'est fugace)
Je vais me poser et tout reprendre depuis le début.
Pour des moteurs 4 temps au dessus de 200 cm3, un site indique :
Gp 122
Ralenti 42
Aiguille milieu
Puit 8 trous.
Une chose est sûre, à froid comme à chaud, des que je mets le starter, ça cale direct.

[charles]

Quand ça cale à l'ouverture brutale, la Gunson semble m'indiquer que je suis trop riche ( c'est fugace)

Ce qui serait fichtrement étonnant.....
À mon avis, c'est l'inertie de la Gunson.
On va tenter d'enrichir en bas, et voir si le trou persiste

[C-paf-O]

Euuuhhhh c'est quoi une Gunson" 

[charles]

un vieux truc des années 1970.
une bougie à culot transparent, qui te permet de voir la couleur de la flamme de combustion.
en fonction de la couleur tu as une idée de la richesse.
c'est pas mal, ça m'avait permis de voire que j'étais trop riche haut dans les tours avec mon 28, de corriger le truc et de gagner un poil.
ça vaut pas une lambda je pense, mais à défaut

[jipéair]

Je ne connaissais pas. 

[bobinesimple Alias Magimojo]

un vieux truc des années 1970.
une bougie à culot transparent, qui te permet de voir la couleur de la flamme de combustion.
en fonction de la couleur tu as une idée de la richesse.

gunson c'est la marque, et ils font 50 000 trucs, déjà au moins les lampes strombo.
c'est donc "colortune" que tu as,
t'es sur que t'arrive à régler autre chose que le ralenti ? le comportement doit pas être le même à vide au point mort qu'en roulant en charge, ou alors t'as accroché ton gosse sur le parechoc et il regarde pendant que tu roules ? 

[charles]

t'es sur que t'arrive à régler autre chose que le ralenti ? le comportement doit pas être le même à vide au point mort qu'en roulant en charge, ou alors t'as accroché ton gosse sur le parechoc et il regarde pendant que tu roules ? 

j'ai dressé un porcelet qui couine deux fois quand c'est riche, une fois quand c'est pauvre.
bien sur, il y a des variations en charge, mais quand déja je suis pourri au point mort, ça va rien donner en charge.
sinon, tu as ça, pour un test en charge (non recommandé par colortune/ gunson)
"
Tuning power/economy with a limited budget
This article has been stolen from Car and Car Conversions from many years past. It is reproduced where as is, and for no financial gain or any other gain than sharing knowledge. All sorts of copyright laws were probably violated... well, tough luck.
   Mixing it on your Own Dyno
   by David Vizard

   The average home tuner's most frequent problem, if the letter
   we get are anything to go by, is getting the fuel/air ratios
   (mixture) right after having tinkered wit hthe motor.  After
   printing this article, we do not expect to get, ever again, a
   Technical Query asking what needles or jets to use on a
   modified motor, becuase this really should be the end of your
   mixture problems!

   When tuning the engine, it is more than likely that the
   fuel/air demand of the engine is changed.  Becuase of this it
   is neccessary to "calibrate" a carburetter so that it passes
   fuel into the engine in the correct quantities for the amount
   of air being consumed.  Over its operating range, a
   carburetter may have to pass a volume from say two to two
   hundred cubic feet of air a minute!  At tickover, the
   consumption of air is very low, but at full throttle the
   opposite applies.

   At every point between the two extremes the air flow
   requirement is different, yet at all these points the
   carburetter is expected to mix the correct amount of fuel with
   the incoming air.  There is little point in trying to set up
   the mixture at tickover becuase very few, if any, of us drive
   on tickover and there is absolutely no guarantee that the
   mixture is right throughout the range.

   How do we know or how can we tell what the mixture is like
   anyway?  Up until now, the most common method has been to
   "read the plugs".  If you have had years of practice and are
   an expert plug reader (not the print on it) you can just about
   pull off the job of mixture setting.  The trouble, however,
   with a plug count is that one is never too sure what the plug
   is saying.

   For instance, a dark, very slightly sooty plug can look like a
   mixture that is just a shade rich, but it could be that the
   mixture is just right and the plug type is too hard (runs too
   cold) for the motor.  Unless you are an expert then, reading
   the plug is, to say the least, just shade dodgy.

   An alternative to reading a plug is to get your engine set up
   on a dynomometer; either the rolling road type or the engine
   type.  When an engine is on a dyno, it can be run at various
   rpm and against various loads, thus simulating the conditions
   met on the road.  While all this is going on, an electronic
   gas sampler can be analysing the exhaust and indicating the
   fuel/air ratio.

   Going from reading plugs at a dollar a time to using three
   grand worth of dyno might seem like going from one extreme to
   the other or to use a comparison, going from an abacus to an
   electronic computer.  What is needed to use the analogy again
   is a slide fule ie: a method between the abacus and computer,
   or to come back to reality, a method of setting the mixture
   which is more akin to the dyno and mixture analyser than the
   plug reading method.

   A dynomometer measures horse power, commonly called brake
   horse power becuase a dyno is nothing more than a brake,
   calibrated to read out the work absorbed and the rate of
   absorbtion.  Here we have a clue; all cars have brakes (or
   should have) so what we have, in effect, is an uncalibrated
   dyno fitted to our car.  To simulate road conditions whilst
   standing still, all we need do is to jack up the driving
   sheels of the car, put it in gear and use the throttle as if
   we were driving along the road.

   To simulate road levels we need only apply varying pressure on
   the brake pedal.  Such action will, of course, get the brakes
   hot.  For our purposes we need to be able to hold full power
   for about fifteen seconds maximum.  If your brakes cannot cope
   with this from the heat point of view, then you are sadly
   lacking in that department so see to it.  It's probably better
   brakes you need and not more power!

   Okay, so we have our dyno.  The fact that it does not read out
   in horsepower is, for our purposes, irrelevant.  What we need
   now is a mixture analyser.  Up until a few years back this
   would have cost a tidy sum.  These days we have a device known
   as a "Colortune" and within the price range that can be
   afforded by the enthusiast, this is the _only_ device we know
   of that will do the job in hand.

   For those who man not know, a Colortune is a device which
   replaces the sparkplug in the cylinder.  The top of the
   Colortune is made of a Borosilicate glass and this allows you
   to see what is going on in the mixture combustion chamber.
   Different mixture strengths burn at different colours.

   By looking into the combustion chamber through the Colortune
   we can get a good indication of the mixture strength
   prevailing.  Inspection of the flame color shows that four
   fairly distinct stages occur.  when the flame colour is
   blue/white, the mixture ration is between 16 and 14:1; a blue
   colour indicates a mixture strength between 14 and 12,5:1; a
   blue/orange colour indicates 12,5 to 11:1 and orange indicates
   11:1 or less.

   The Colortune, then, is indicating at the colour transition
   points the mixture strength of the ingoing charge.  Maximum
   power occurs when the fuel/air ratio is between about 12,5 and
   13,5:1.  The exact point varies from engine to engine, but
   most cast iron tuned production engines seem to be best around
   12,8:1.  The best economy is achieved on weaker mixtures than
   that giving maximum power, and fuel/air ratios between 14 and
   16:1 seem to be the easiest on the pocket.

   To set up the mixture in the manner about to be described you
   will need an accomplice.  The first and essential step is to
   part the car in some place which is poorly lit, so that you
   can see the combustion colours.  Jack up the driving wheels of
   the car until they are just clear of the ground and in the
   interest of safety, securly blockthe car so that it cannot
   move under any circumstances.

   At this point, warm up the engine, the remove a spark plug and
   replace it with a Colortune.  Set up the mixture so that you
   have a fuel/air ratio of about 12 to 12,5:1 (orange/blue) at
   normal tickover revs.  If you have multiple carbs you will
   have to do this for each cylinder or set of cylinders having a
   carb.

   Next, get your accomplice to put the car into gear, usually
   third gear is best, and increase the throttle opening but at
   the same time put on the brake.  (Continue opening the
   throttle and increasing breaking pressure until your
   accomplice ends up with the throttle wide open and the revs
   pulled down by braking to 2000 rpm).  You can now look ath the
   Colortune and at this point it will reveal what the fuel/air
   ratio is under the prevailing conditions.

   It can then be noted, preferebly by colour rather than
   reference to its fuel/air ratio.  After this, let the brakes
   cool for a few minutes, then repeat the procedure at 3000 rpm
   then at 4000 rpm and finally at 5000 rpm, stopping to let the
   brakes cool between each run.

   As far as brake overheating is concerned, it should not take
   more than fifteen seconds to ascertain the mixture ratio at
   each rpm interval, so they will be well within their capacity.

   Once you have an indication of the state of affairs of the
   fuel/air ratio up the rev range to 5000 (5000 rpm is the limit
   on the Colortune) the necessary corrections can be made to get
   it right.  Not only can the full throttle conditions be
   catered for in this manner, but so can part throttle and
   transient conditions.  For instance, a hesitant pickup when
   going from parth throttle to full throttle could indicate that
   the mixture is too weak during the transition from one state
   to the other.  During the transition period and for a short
   while after the Colortune should show a rich mixture
   condition.  If it doesn't, then you can bet your life that on
   a fixed jet type carb, the accelerator jets or pump stroke are
   inadequate.

   On carbs like the SU and Stromberg CD variety, a lean mixture
   during the acceleration phase would indicate that the damping
   is insufficient.  A thicker oil is usually required to
   compensate this.

   A couple of cars were used as guinea pigs to test the method.
   Both cars were modified and therefore required different carb
   settings.  In each case the carburation has been originally
   set up by the owners who had only an average working
   knowledge of what was required.  After use of the Colortune by
   the mothod just described, both power and economy were better
   between 5-8bhp and 10-15 miles per gallon.

   The reason that consumption was so much better after use of
   the Colortune stemmed from the fact that the mixture was
   originally set rich for maximum power and unfortunately
   becuase of the guesswork method of setting, it was too rich.
   The performance increase was better than the power increase
   alone suggesting that the mixture was right (within limits)
   throughout the rev range.  As a side effect this led to a
   smoother running engine with a snappier throttle response.

   To sum up, the Colortune proves to be a very useful device.
   It can, at a price of 4-87,5 UKP easily justify its place in
   the tool kit of any self-respecting enthusiast, and its
   intelligent use can only bring about an increase in
   performance.

   Editor's note:

   Whilst David Vizard has used this tuning method successfully
   with both a Mini and Austin 1100 its use on many other types
   of car could possibly be dangerous.  Firstly therefore we
   recommend that the suspension characteristics and drive
   shaft-prop shaft geometry of the car in question be checked
   carefully ebfore even considering use of this method.

   On rear wheel drive IRS cars which may have large wheel
   angularity, attempt to jack the car at points on the
   suspension that will allow the wheels to assume a position in
   angle similar to that which exists in normal use.

   On a non-IRS rear wheel drive car jack under the springs on
   either side at the axle location point.

   Make sure jacks are very secure and will not move under
   testing vibration, also make sure any car to be tested has
   alternate props underneath in case of jack failure -- ie:
   spare wheels and tyres which should be first tested using the
   full weight of the car.  One advantage of the DV method is of
   course that during load tesing the wheels on the ground have
   the brakes applied.

   On a Mini the best method Vizard found was to put a piece of
   wood on top of trolly jack lift point and jack up from the
   Mini sump.  Once having jacked car up, jam wheels and tyres
   underneath car for safety.  Car does rock but cannot thus fall
   over.  Drive shafts will assume peculiar angles during testing
   and this can be minimised by supporting bottom suspension arms
   on axle stands --these can however move and you may have to
   take the risk of the odd shaft angles for the few moments of
   testing.

   This method does not apear to be practical with swing axle IRS
   cars ie: Herald, Spitfire, Vitesse Mk 1, GT6 Mk1.

[bobinesimple Alias Magimojo]

t'as donc un porcelet qui accélère et qui freine en même temps sur chandelles pendant tu zieutes la bougie  ? 

[charles]

 
gros boulot de dressage, faut aussi qu'il controle le compte tour.
d'ailleurs, faut que je me dépêche de régler le pwk, bientot la saison du figatellu 

[charles]

 [ You are not allowed to view attachments ]
juste pour expliquer pourquoi je galère. sachant que quand on demonte la cuve, il faut faire attention à ne pas brusquer le flotteur, sous peine de tout fausser (dereglage du niveau de cuve)
j'ai refait un petit essai ce soir:
gicleur de "ralenti" de 45
principal en 110
puits 8 trous
aiguille "naraku spéciale 4 temps" remontée d'un cran.
je suis riche de chez riche partout, le moteur peine à prendre des tours, mais je n'ai plus de gros trous
je vais remettre l'aiguille au cran 3, puis, si ça reste suffisament riche en bas, diminuer progressivement la taille du principal jusqu'à etre bien en haut (je n'ai pas en dessous de 100 ).
apres, on passera au reste
comme je pars du néant, si ça se trouve, je vais m'apercevoir à la fin que c'est la coupe du boisseau qui peche.
heureusement qu'il me faut moins de 20 minutes pour réinstaller mon 28 et rouler un peu

[mitch83]

aiguille "naraku spéciale 4 temps" remontée d'un cran.
je suis riche de chez riche partout,

tu étais trop riche, et tu remonte l'aiguille donc tu vas être encore plus riche !!!! j'ai du mal à suivre