Alez
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 posted on 1/4/04 at 07:03 AM |
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One cylinder not working
Chaps,
Since yesterday and for no known reason, my Blade engine is running on 3 cylinders. I noticed it as soon as I started the engine because of the
increased vibration, then the decreased idle speed (wanting to stop) and then.. touched each of the exits of the mainfold and saw 3 warm 1 cold.
Since Jon used to keep a HT coil in his tool bag and Tom used to do the same, the first thing I thought was it must be the coil gone, maybe they go
often, same as for the fuel pump. But then I took a look at the Haynes manual ignition diagram and realized there is one coil only for each 2 spark
plugs, so you just can't have only 1 failing because of a faulty coil. Unfortunately, I had to stop the investigation since I didn't have
a spak plug spanner handy yesterday, but I'll continue today.
So I thought I'd share this with you guys today, to get advice about the most likely cause I should expect. At this stage I can't think of
anything other than what goes in the path from the coil to the spark: cables, plugs, spark plugs. I'm not sure that there's anything other
than ignition that could realistically be the cause, I was running very fine last day I drove the car and I haven't done anything to it.
Theoretically, I guess it could be the sensor that gives pulses to the computer (ignition pulse generator)? But I'm not sure that's a
likely fault. Any other cause I should realistically consider? Anything not ignition related?
Many thanks!
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Mk-Ninja
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| posted on 1/4/04 at 07:35 AM |
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Do the simple things first, it will most likely be a dirty plug or broken lead. So put a new plug in and a new HT lead.
HTH Gordon
I'm sure I've got one, just don't know where I've put it
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ChrisGamlin
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| posted on 1/4/04 at 07:40 AM |
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Hi Alex
Easy way to check the spark is to get a spare spark plug (or take out the original), then pull the lead off the cylinder in question, plug in the
spare spark plug, then rest the plug against bare metal on the engine (to earth it). Now turn the engine over and see if you can see a spark. In an
ideal world you'd do this with proper insulated spark plug pliers but if you dont have any of those maybe use some well insulated regular
pliers and gently hold the rubber part of the coil lead to avoid getting a shock (Ive done it holding the rubber with my hands before but usual
disclaimer if you still get a shock tho!  ) .
If you get a spark with a spare plug, then try again with the original plug as it may have fouled up or not be connecting to the coil lead
properly.
If neither work, try unscrewing one of the plug leads (they do undo off the coilpacks) and swapping it around to another cylinder. If the failure
follows to the other cylinder then its likely that the lead is up the creek, if it stays on the same cylinder with both leads then its something else,
maybe one of the pulse wires going to the coil packs?
Check over the carbs too, you might have a needle blocked or something like that.
Chris
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Alez
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| posted on 1/4/04 at 08:49 AM |
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Cheers, guys! Yes I'm buying the spark plug spanner today, together with a set of spark plugs should I need them (the shop is not very close to
my garage, so I better do it in one go).
Thanks for the explanation Chris, it's the exact same procedure described in the Haynes manual, I'm buying the spark plugs also in order
to have a spare to follow this procedure. In principle, the pulse wire going to the coil pack can't be the culprit, this is because each of this
wires is responsible for the spark of 2 different spark plugs, so a failure would make 2 cylinders fail at the same time.
I'll read the Haynes manual to learn how to dismantle a carb in order to see the needles..
Many thanks.
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Hellfire
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| posted on 1/4/04 at 09:26 AM |
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Alez...
we had exactly the same problem... it was found to be a loose spark plug shroud. Make sure they are very firmly pressed onto the spark plug cap! Any
lack of condutivity will cause this. Strangely enough it was our #3 too
ATB
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Alez
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| posted on 1/4/04 at 10:08 AM |
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Thanks! Well actually it's not my #3, I just said I had 3 working 1 not! It's my rearmost (bike left one), I'm not sure how they
are numbered. Anyways, good info.
Cheers,
Alex
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timcrasher
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| posted on 2/4/04 at 09:22 PM |
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Misfiring blades
Hi, Alex.
I've just read your post and the answers you have received. The most popular cause on fireblades I have come across is an airleak. On the back
of the cylinderhead under each inlet is a small blanked off takeoff to allow for the attatchment of carb balance guages. The little blanking covers
either perish or fall off all the time. I always have a packet of these covers in my toolbox at work because its so often. It is normally #1 or #3
cylinder that is missing as these are the hardest to get at on the bike, and dont get put back on properly.
Its a simple thing to check, and it causes the problem you desribed. If one of the blanks is missing you will need to change the coresponding spark
plug as it will be knackered.
Hope this helps
Cheers Tim
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Alez
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| posted on 13/4/04 at 12:08 PM |
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Many thanks Tim. It happened to be something to do with cables and spark plugs. No spark plug was "knackered" really but after checking
the 4 cables I was experiencing intermitent faults. I then changed the 4 cables and spark plugs and was aaall fine.
Cheers,
Alex
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