tubeglower
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 posted on 11/8/14 at 02:06 PM |
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Kawasaki BEC troubles
Hello all! I must say this forum is very nice and helpful, so hopefully I can fix some problems I am facing with my project.
I must apologize for my English, since it is not my mother language, hopefully you guys will accept that.
I've just got a unfinished project from a third person, it is a bike engined off-road buggy. The project is in a decent progression, I would say
60% done. The chassis fully welded, suspensions and steering fitted, brakes there but with no hoses, engine assembled in the chassis, central chain
transmission done with the only missing parts being the side transmission axles.
I've got a Kawasaki 1100 engine on it. Here there are the first question marks, since I am unsure if it is a ZZR 1100 ('90 to '93)
or a GPZ 1100 from the 90s. The engines apparently were very much the same with some minor changes (I heard camshafts, CDI and carburetors might
differ). I've got workshop manuals of both models. The engine comes with its stamped number, wich is ZXT10CE067344. I didn't got the
complete set of parts, but I got a CDI (from an early ZZR 1100), two kawasaki "connection boxes" which I think I want to skip, a set of
carburetors in semi-decent shape (which I believe are CVKs used in a GPZ 1100 or a ZX10 Tomcat since they are 36mm with main jet 100, another
difference is that most of the CVKs 40 pictures I've seen are with the intake side elliptical, being the ones I have round intake sides).
So this is my salad. I am unsure on the engine model, but other thing that makes me think it is a ZZR 1100 is the pick up connector, which has 2
terminals, and in the case of the GPZ it should be a 4 terminals connector due to a different CDI connections arrangement.
My intention is to start the engine and see that it works, then continue with the rest of the work.
Ok, what is the problem then? It will no start doesn't matter what I do!! 
What I've done so far:
- Connections with the CDI, I don't use the kawasaki connections box, so the CDI is directly connected to the pick up, battery and HT coils. It
works, at least I get nice and blue powerful sparks in the four plugs when I spin the engine.
- Cleaned up the carbs 3 times, set the level and revise all the jets, diaphragms are nice and relatively fresh, no holes or damage on them.
- Connect the starter motor relay and a starter push button, it works nice and when I press the start button I get the starter motor spinning, noise
is good and it moves the engine accordingly.
- Checked that the camshafts are assembled right, since the engine didn't start at all and I don't know who was touching this engine
before, but it is right timing and the IN and EX camshafts are in the right position.
So what I am missing? The system has fuel and air mixture, in theory, via the carbs, it also has spark when rotates, but doesn't want to start,
doesn't matter what order I use in the plugs (I know left HT coil takes care of 1 and 4 cylinders and right HT coil takes care of 2 and 3
cylinders).
I don't have a fuel pump, so I am feeding the carbs by gravity using a direct hose. I don't have the airbox and air filter.
What is missing here?
- Do I must to have a fuel pump in the system to start the engine? Do the carbs really need that low pressure in the fuel to actually feed the
cylinders?
- Could it be a problem in the CDI? Even when I get the spark? maybe it doesn't work properly and is not correcting the ignition curve with the
right degrees for easy starting?
- I now the miss and match cocktail I have probably will not make the engine working good, but at least it should start and roar for a some seconds,
then I will work out in the rest...
I appreciate any idea, I am out of inspiration right now.
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tomprescott
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| posted on 11/8/14 at 02:25 PM |
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Can't speak about yours in particular but most bikes I've worked on have been wasted spark - as a result it shouldn't matter if you
have one and four mixed, or two and three mixed - but if you some how mix the connections to the main loom you could really have problems - so make
sure the coils themselves are connected properly.
The next thing is timing - if you have a service manual, check the timing: the CDI will take a reading from a hall sensor working against the crank
(the stator) - often behind the left-hand lower engine casing. Unlikely that this is the problem unless someone has fiddled with it.
Carbs! Try adjusting the pilot screws - each carb will have a screw which either adjusts a fuel mixture (if on the engine side of the carb, or the
amount of air input (on the airbox side of the carb) - small fluctuations in idle speed (0 - 1/8 throttle) can be ironed out by these screws and bike
engines are usually sensitive to them. Lightly seat the screws by turning them all the way in, and then back them out a bit (your book should specify
how much, a 'guess' amount would be 1.5 turns) and see if that helps, then experiment from there. The screws are usually on the underside
of the carbs, can be a fiddle to get too and are usually best tackled with the carbs off the engine.
The other things you should look for are air leaks in the carb boots to the engine (spray with wd40 to identify if there are any leaks) and if you are
getting enough fuel in the float bowls (take the bottom off the carbs and see where the float height is set, check against book spec).
Hope this helps!
A bird in the hand....
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tomprescott
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| posted on 11/8/14 at 02:43 PM |
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AH, the other thing to say is that if they are non-original carbs, it is possible (perhaps likely) that the carb is the wrong size and/or not jetted
correctly for your engine - get a service manual and see what the standard carb and jets are to compare.
The CDI is essentially a capacitor (although has a lot of complex circuitry inside so difficult to test with a multimeter) - if its goosed then you
usually won't get spark, but do check the timing is set correctly at the stator as per my post above. Be glad that it doesn't appear to be
the CDI, as they're expensive to replace - but it may be an issue if your CDI doesn't have the same ignition map.
Shouldn't need a fuel pump if the carbs have enough fuel in the floats to keep it going - I would expect to be able to run the bike for a few
minutes from a full float bowl (i.e. without a tank attached).
Sounds more likely to be a carb problem but you can spend a lot experimenting with different needles and never get close if the CDI isn't
compatible with your bike.
Go online and find a manual, there are lots of places that have them for free - you'll want/need one.
A bird in the hand....
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tubeglower
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| posted on 11/8/14 at 04:06 PM |
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thanks for your input tomprescott...
Unfortunately, all the steps you mention were in my checklist and gone over them all over again and again... No success.
The engine has got spark and fuel/air mixture, that is for sure.
I've just checked one more thing, cranking the engine and not starting, if I put a lighter in the exhaust pipe, a nice flame comes out, so
apparently I am getting some decent fuel/air mixture that the engine is pumping out.
The carbs might be or not of the model of the bike, but they certainly can go together, since some models made that combination (1100 engine with CVK
36 in the GPZ), I am prone to think that they should be good enough at least to start the engine.
There are no leaks in teh carbs, all the vacuum hoses are sealed, I can check in the rubber boots that connect the carbs to the intake ports, but I
doubt it is so severe to avoid any starting if actually tehre is any leak there.
Turning my attention to the CDI, it might happen that even when I am getting a nice spark when I do my connections, the CDI is not giving the right
timing... Is it actually possible a faulty CDI doing that? that might be an interesting approach, I was more in the opinion that they either work or
not, but...
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tomprescott
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| posted on 11/8/14 at 04:40 PM |
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I'm the same as you re the CDI, they tend to work or not - but if for a different engine might be working, taking the signal from the stator but
sending the spark at the wrong time.
Old practical joke was to put the stator to one extreme so that the engine ran in reverse, if all else fails you could try shifting the stator until
you find timing that hits?
A bird in the hand....
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ReMan
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| posted on 11/8/14 at 05:24 PM |
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Hi and welcome
I'd agree that you should get it firing/running roughly with any carbs/fuel and a spark.
Are you sure you have some compression? (this should clarify if the cams and timing have been put together right?
Is the spark happenning when the piston is close to compression? Pull a plug out and shine a torch down the plug hole to see this with the plug on the
head still sparking?
If yes to both above, have you tried with some easystart spray in the carbs,.
Sorrya a bit roufgh and ready, but as said, you shold be getting some signs of life
www.plusnine.co.uk
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maccmike
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| posted on 11/8/14 at 08:12 PM |
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Standard ZZR c1 has 40 carbs and 155 mains and yes they have a wasted spark.
Take a plug out and turn it over to check for spark.
It is possible to have leads on wrong plugs even with wasted spark.
Chase the wires from the CDI, you can work out which plugs theyre to go to.
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tubeglower
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| posted on 12/8/14 at 01:13 AM |
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Well, thanks all for your ideas and suggestions.
I've investigated a bit the situation with the pal that started the project, he bought the engine with the carbs together, apparently coming
from the same bike, a zzr 1100 from early 90s, so a C model. The engine is actually numered as a zzr 1100 C model (zxt10c...) a gpz model would have
been numered as zxt10e... It seems the carbs, even when they were bought with the engine, are not belonging to this model or the model was an exotic
version with restricted power or something like that, but that is not relevant because the engine should start with cvk40 as well as with cvk36
carbs.
The cdi was adquired separetely, but it matches the engine and year, since the connection with the pick up is compatible direcly, the rest of
connections I tinker them myself to overrun the connection box and the safety switches (sidestand and clutch/neutral). Which I understand I am
succeding since I do have spark in all of the four plugs.
The engine has compression and I've checked that the camshafts are right in place (exhaust and intake where they should be). Also checked the
marks in the pickup coil and the camshafts, so the engine is correctly timed mechanically, which makes sense because when I spinn it, it sounds good
without any strange noise like hitting valves.
With fresh fuel feeding the carbs by gravity, and having spark, it will not start, it is the same with or without choke, pumping the acccelerator or
no, spraying easy starter, or anything. I know the mixture is supplied to the engine because if I put a spark in the exaust pipe (a lighter), I get a
quite big flame out of it while I am cranking the engine with the starter motor.
It is extremelly weird. To me there is only the possibility that even when I do get a spark, it is not at the right moment, wich according the manual,
sould be 10 degrees before tdc @ 1000 rpm. So the cdi is not giving the right timing. Is there any other possibility? Anyone with some idea on how
could I check if the cdi is giving right timing? Do I miss something?
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tubeglower
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| posted on 12/8/14 at 01:21 AM |
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quote:
Originally posted by maccmike
Chase the wires from the CDI, you can work out which plugs theyre to go to.
I've done that, and the black wire was to the left HT coil and therefore 1-4 cylinders and the green wire was to the right HT coil (2-3
cylinders). I've also checked the oposite and all the combinations with the connections to the HT coils and the plug positions (even when I knew
it didn't make sense), but it is what you do against desperado mood.
Really annoying to be honest!!
[Edited on 12/8/14 by tubeglower]
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40inches
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| posted on 12/8/14 at 07:36 AM |
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Perhaps not relevant to your engine, but you never know
On the ZX9R (and other models) the grey feed from the ignition to the CDI/ECU should be 9volts, it's an anti theft measure.
So if you have an ignition to CDI feed, it may be worth fitting a 100ohm resistor in line. Just a thought
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tubeglower
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| posted on 12/8/14 at 10:23 AM |
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quote:
Originally posted by 40inches
Perhaps not relevant to your engine, but you never know
On the ZX9R (and other models) the grey feed from the ignition to the CDI/ECU should be 9volts, it's an anti theft measure.
So if you have an ignition to CDI feed, it may be worth fitting a 100ohm resistor in line. Just a thought
Good point, I am affraid that in this case that is not an option, or at least it doesn't appears in the manual. This system you reffer is
probably in more modern bikes, this is a 90/92 model. Also, at the end of the story, I imagine that if you don't feed the grey wire with 9v in
the zx9r, you will not get any spark, which is not at the very end the case, since I get spark.
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