Steve Saunders Goldwing Forums banner
Status
Not open for further replies.
1 - 10 of 10 Posts

·
Premium Member
Joined
·
23 Posts
Discussion Starter · #1 ·
cylinder 3 loses all spark @ 1500-1700 rpm..... coils have been replaced with brand new coils (from a 1979 cb750) wires have been swapped around.... spark generators has been checked and is at 1200 ohms and 1150 ohms..(as by haynes manual... checked through connector in front of battery)..
connections have been checked on coils.... strong spark all round except for during dead spot...

Now thinking it must be the ignition control unit...
Any ideas?
 

·
Premium Member
Joined
·
23 Posts
Discussion Starter · #3 ·
84 gl1200

84 gl1200
now the spark has returned, yet the 3rd cylinder´s plug is blackened... and there is still a miss and a cough .... engine seems to rev up fine, but hesitates until above 2000 rpm
This bike is really messing with my head
 

·
Administrator
Joined
·
27,898 Posts
If it looses spark on #3 it will also loose it on #4 unless the problem is in the plug wire, cap or plug.
 

·
Junior Grue
Joined
·
8,153 Posts
84 gl1200
now the spark has returned, yet the 3rd cylinder´s plug is blackened... and there is still a miss and a cough .... engine seems to rev up fine, but hesitates until above 2000 rpm
This bike is really messing with my head
I see a carburetor rebuild in your future.:readit:
 

·
Premium Member
Joined
·
2,790 Posts
i have seen where at low rpm a spark plug cap was intermittent but above 2000rpm ran fine,cured it by replacing the wires with taylor spiro pro wires which eliminated caps completely,one easy way to check is to replace the resistor in the cap with a shunt and see if problem is eliminated
one sei owner on the site was having same problem and replaced the caps,and after that didn't help found that the coil had cracks in it,repalced a coil and now runs fine
but since you have carbs,could even be a problem there,considering this is a over the winter new developed problem,you may have some water or fuel separation problem too,drain the fuel bowls and maybe add a little dry gas,maybe even some seafoam could clean out a low speed jet
just dont make alot of changes at once and then never know what fixed the problem
 

·
Premium Member
Joined
·
23 Posts
Discussion Starter · #8 ·
carbs have already been rebuilt..... fully clean, new fuel filter, air filter is clean, spark generators checked, coils replaced, going to get new caps and wires today and do a compression test, while sitting on the bike it is the left rear plug fouling (not wet, just sooty)
 

·
Premium Member
Joined
·
2,163 Posts
while sitting on the bike it is the left rear plug fouling (not wet, just sooty)
That is the #4 carb, not number three. It may seem picky, but #4 is "inline" with more problems because there are two vacuum ports associated with it.
There is a manifold vacuum source at the bottom of the intake runner that operates the vacuum cut as well as the secondary air supply.
Both of these systems operate correctly with no vacuum supplied, they only close during decel.
Plug the vacuum port on the runner and see if it makes a difference. You could have a ruptured diaphragm, a split hose, or a vacuum line off.
The second vacuum line is ported vacuum. It only operates off idle, and sends the signal to the cdi. You can plug this port for test purposes as well.
Do one at a time, see if either makes a difference.
 

·
Premium Member
Joined
·
2,163 Posts
#4 is "inline" with more problems because there are two vacuum ports associated with it.
There is a manifold vacuum source at the bottom of the intake runner that operates the vacuum cut as well as the secondary air supply.
Both of these systems operate correctly with no vacuum supplied, they only close during decel.
Plug the vacuum port on the runner and see if it makes a difference. You could have a ruptured diaphragm, a split hose, or a vacuum line off.
The second vacuum line is ported vacuum. It only operates off idle, and sends the signal to the cdi. You can plug this port for test purposes as well.
Do one at a time, see if either makes a difference.
Posting it three separate times will not get you any better advise than you've already been given.
 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top