#2 cylinder not heating up

[racquetman]

81 GS850L fires right up w/o choke. Just had carbs rebuilt, yet the #2 cylinder remains cold when the other three are heated up. I laid a firing indicator on each spark plug wire, the #2 looked weaker than the other three. Any ideas? Thanks in advance.

 

[Suzuki_Don]

To start with replace the spark plug in #2 and remove old spark plug cap from HT lead. Cut 1/4" off end of HT lead and fit new spark plug cap. See how that goes.

 

[racquetman]

Thanks, btw they are all brand new plugs. HT?

 

[Suzuki_Don]

Thanks, btw they are all brand new plugs. HT?

HT = High Tension lead or spark plug leads.

 

[Guest]

Pull the vacuum line off the petcock, plug it, put it on prime and see if it heats up then.

 

[chuck hahn]

Bill..If the other three are firing and getting hot then it stands to reason that fuel IS passing thru all 4 carbs..fuel cant get to 1 or 4 without passing thru 2 and 3 via the transfer tubes. So that would mean that the petcock is working WITH the vacuum line attatched and letting fuel flow or else none of the carbs would have fuel. I was wondering what plugging the vacuum line and putting it on prime will do? Now one coil fires 1 and 4 and the other fires 2 and 3.. What i am wondering is would it be possible that since he stated that #2 has a weaker reading than the other three can one sdie of a coil go bad and cause this? I was just wondering.. i have never heard of a coil going bad and not loosing both cylinders it supports.. just wondering because myself and Scot Janes were checking this out as we were gatting him registered and showing him around the forum.. Not saying your wrong or anything... just curious about this...

 

[Guest]

The vacuum line is pulling extra fuel into #2. I bet if he pulls the plug it is black.
The petcock is still operating but the diaphram is leaking.
This is my best guess since I'm not looking at the bike.

 

[Steve]

Just because fuel is going through #2 carb to get to #1 does not mean that it's getting past the float valve into #2. :-k

If the petcock diaphragm has a leak, and the float valve in #2 is stuck closed, there might be some fuel getting to the cylinder, but not the right mixture to fire, so eliminate the source of the possible leak.

It's not impossible for one side of the coil to fail, but it is highly improbable. It's more likely that there is a bad connection from the wire to the cap or a fouled plug.

.

 

[chuck hahn]

Thanks for the answers. and steve i thought the same about the coil failure. I havent experienced one myself but i have always heard it kills both or it fires both...usually no in between.. makes sense.

 

[bwringer]

The vacuum line is pulling extra fuel into #2. I bet if he pulls the plug it is black.
The petcock is still operating but the diaphram is leaking.
This is my best guess since I'm not looking at the bike.

^^^^ This. ^^^^

 

[racquetman]

Thanks for the help guys/gals. I did pull the #2 plug and yep it was pretty carboned up black, looked at #1 and was clean. Looks like time to invest in a new petcock diaphram? Special thanks to BWRinger, that's why you are a superstar!

 

[Big T]

Thanks for the help guys/gals. I did pull the #2 plug and yep it was pretty carboned up black, looked at #1 and was clean. Looks like time to invest in a new petcock diaphram?

Get a new petcock

Rebuilding them rarely is successful

 

[racquetman]

Thanks Big T. Along with everyone else. Y'all are the best.