1150 has lost #2 cyl..

[Guest]

Hi Folks,
my 84 1150EF is mis-behaving again and driving me...
This year, following a top end rebuild to stop leaky base gasket it has exhibited a charging concern, but otherwise running GREAT. (another new stator is on order)
She also has a new petcock, so yes, I know the symptoms when that diaphragm gives out. (the rebuild kit fixed the leak but it quickly became too stiff to turn for reserve)
Decided to go for a quick ride this morning but clearly not running well, slower idle and some popping n the exhaust. Ran down the road but was way down on power and not happy at any throttle opening.
Back home my opti temp sensor identified #2 as pretty cold.
Pulled plug cap and used old plug to ground, spark looked pretty good, so I ass-u-me that the problem is with the fuel feed.
Really do not want to pull the carbs, will not know where to stop for one thing, besides being a pain of a job...
Looking for clues as to what would make such a sudden black / white change?
Had thought of looking at the vac diaphragm in top of carb, but then thought that it would still fuel at idle, so stopped.
Now thinking to drain float chambers of 1 and 2 to compare?
Thoughts / help appreciated..

[tom203]

I know what you're thinking....." It can't be my sorta new petcock". Why not check by sticking some clear tubing on petcock vacuum fitting and sucking? #2 being cold makes me suspicious so rule it out before you enjoy carb removal fun!

[qcktvr]

I hear you Tom, being #2 again went through my mind as well, but this petcock is now really "new" and the symptoms are quite different than when I had that vac line sucking extra fuel, surging and rough idle, but still plenty quick.
Tank will go back on again and will retest and report...

[qcktvr]

Unfortunately not that simple this time; just the same with the vac line plugged and petcock on "pri".
#s 1,3&4 exhausts heading to 400 while #2 stuck at 110F.
I do not intend to do a full carb rebuild, just want to find a problem and fix it...
Stuck float valve, chunk of dirt?? Hopefully it will be easy to find as I do not have any new seals and gaskets for these things...
Any thoughts as to where to start looking?
Regards

[dorkburger]

If the petcock is hard to turn, is there a chance that something inside is misplaced and causing a fuel starvation issue? Just hazarding a guess, as ive not yet had to open one up... what if you take a romp with the valve in prime?

[qcktvr]

Hi, just to confirm, the petcock is a new piece, put on this summer, turns real smooth and easy. ( just has res & pri switched compared to the old one).
Last time out it ran like a champ, today #2 is not supporting the cause.
Just going out again to pull #2 plug as I had checked for spark with an old / spare plug.
Unlikely, but.... still hoping..

[qcktvr]

Whew... thank goodness I did that last plug test!!
Spark had looked good using a spare/old plug, BUT when I pulled #2 plug it was wet and when retested it had no spark.
Still looked fine and no more than a couple of thousand miles on it, an NGK..
Put the old one in and she is now a much happier 1150, will try that ride again tomorrow.
Another lesson learnt, I was reluctant to pull the carbs as the float valve is the only thing that I know that would shut off all fuel to one, and then it should have had a full bowl for starting; but then in millions of miles of driving / riding I cannot remember having a plug die, except with a bridge across the gap with old 2 strokes..
Thanks for those suggestions

[posplayr]

I have had a cracked insulator causing a bad plug. You have to be very careful when you remove them and don't put a side force breaking that insulator. Not hard at all if you are careless.

[Tom R]

Not a bad idea to check the resistance of those insulator caps while you're at it. They're supposed to be 5 ohm; but the resistors seem to fail over time. The readings on my 1100's caps ranged from 12 to 34 ohms on 3 caps, and the 4th showed infinity on my little ohm meter. The bike ran on all four cylinders, mostly,before changing them; but definitely runs better now.