1981 Cylinders 1,4 not working

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hawk
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1981 Cylinders 1,4 not working

Postby hawk » Tue Sep 19, 2017 1:48 pm

I am hoping someone can point me in the correct direction as I am stumped.

Cylinders 2,3 are working fine, cylinders 1,4 aren't working. Here is what I have checked
-Spark present on 1,4
-Compression good on 1,4
-sprayed carb cleaner in 1,4 through spark plug hole, no difference.
-Swapped ignition coils between 2,3 and 1,4
-swapped spark units between 2,3 and 1,4
-checked spark generator gap
-checked valve gap (leash I think is the correct term)
I even went as far as removing all spark plugs, manually turning engine while looking at piston, valves in #2 and spark generator position during phases of engine to ensure valves on all cylinders are at the same place when piston is at same position. Example, when #2 is on compression phase and cylinder is at top, both valves are closed and next to open would be exhaust, timing would have just happened. Rotated engine, to put #1 on compression and checked to ensure valves are same as #2 was and timing is same distance as was on #2. I also blew smoke into spark plug opening to ensure none escape through intake or exhaust.

At this point I have no idea what else to check.

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GeorgeSweety
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Location: UK.

Re: 1981 Cylinders 1,4 not working

Postby GeorgeSweety » Wed Sep 20, 2017 2:13 am

Hi Hawk, if you have swapped the coils and spark igniters from one side to the other and the result was the same, ie the bike still fired on 2 and 3 then I would suspect either the wiring or the CDI pick up under the right hand engine cover.
On my bike it is the left pick up for number 1 and 4 cylinders but off the top of my head I can't recall the wire colours, either blue or yellow. Have you checked the gap between the rotor and the CDI pick up under the right hand engine cover?, don't use a feeler gauge or you may be in for a shock, use a sheet of thick paper or thin card. The first thing I'd do would be to put the bike on the centre stand and remove all the plugs from the engine but place them in their caps so that they are in contact with the metal on the cylinder head. Then rotate the engine either by putting the bike in gear and rotating the back wheel (preferable) or by turning the 22mm nut on the right hand side of the engine clockwise (gently as the 22mm nut is a dummy on a very thin shaft) until the pip on the rotor lines up with the pip on the pick up. I can't recall if the ignition needs to be on or not but try the next bit with it on. Take a screwdriver and touch it across both the pips and see if number 1 and 4 plugs spark, if they don't I would unplug the electrical connector and get some fine emery paper and electrical cleaner and get the connectors clean, cut the emery into thin strips and get it inside those connectors. Then do all of the connectors on that side of the ignition all the way up to the coils.

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GeorgeSweety
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Re: 1981 Cylinders 1,4 not working

Postby GeorgeSweety » Wed Sep 20, 2017 3:00 am

Just re-read your post, I was rushing to get the kids off to school when I replied. Didn't notice where you said 1 and 4 had spark, I've had spark on plugs before but the cylinders wouldn't fire as the spark wasn't strong enough. I'd still check the gap on the rotor and pick ups then clean the electrical connectors. Are the plugs wet with fuel after a start attempt? how long has it been since the bike last run?

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Folsoml
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Re: 1981 Cylinders 1,4 not working

Postby Folsoml » Wed Sep 20, 2017 5:37 am

GeorgeSweety wrote:... or by turning the 22mm nut on the right hand side of the engine clockwise (gently as the 22mm nut is a dummy on a very thin shaft)


I always recommend using the rotor bolt on the other side of the engine to do this--even though a clymer or similar manual recommends the 22mm nut. GeorgeSweety is correct in that this nut is fragile.

I did not see that you've done anything with the carbs.
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GeorgeSweety
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Re: 1981 Cylinders 1,4 not working

Postby GeorgeSweety » Wed Sep 20, 2017 12:25 pm

Folsoml wrote:
GeorgeSweety wrote:... or by turning the 22mm nut on the right hand side of the engine clockwise (gently as the 22mm nut is a dummy on a very thin shaft)


I always recommend using the rotor bolt on the other side of the engine to do this--even though a clymer or similar manual recommends the 22mm nut. GeorgeSweety is correct in that this nut is fragile.

I did not see that you've done anything with the carbs.


Well that's what a smart guy would do but I never claimed to be smart :lol:

cb650
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Re: 1981 Cylinders 1,4 not working

Postby cb650 » Thu Sep 21, 2017 4:21 am

maybe a bad wire or connector somewhere.
Did you clean the tank out?!?!?!?!


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