If it aint broke, DON'T FRACKIN FIX IT!!!!!!!!!!

I have a 76 kz900 A4. All stock except for 4 into 2 MAC slip-ons. Got it a year or so ago. Finally got it running really good this spring.

I've been reading posts about how to clean fuel system, crank case, and combustion chambers.
-So I ran a tank of fuel with Sea Foam. No problem.
-Then last night I put some Rislone combustion chamber cleaner in and left it over night.
-This morning I went out, pulled out the plugs again and kicked it over a few times to purge. Plugs back in, hit the starter, couple of turns and BAM! Huge back fire. Try it again. BAM! Try it again it fires up, seems fine.
-Put 1/2 can Sea foam in the crank case. Go for a 30 Km (20 mile) run. Doesn't feel quite right, but not bad.
-Get home, change oil. Start it up. Sounds off. Pull it out of the garage. Notice a miss right away. I go for a short spin. Miss is still there.
-Spray water on head pipes. #2 is cold. Check plugs, #2 is black and sort of wet. Check compression, not great, but no change from before. Check spark, OK. Check timing and points, spot on. Change coil, no difference.

WTF!! HELP ME PLEASE!! I was planning to ride it to the Vintage Bike Show and swap meet on Sunday. I don't really want to ride it on three cylinders.

Have you gone through all the gas in the tank?
If not run it (personally I'd dump it) and get some fresh gas and a new set of plugs in there...

"Finally got it running really good this spring."... And you did this gas treatment why when it was running good.... :whistle: I know, I know...

Also check your carb air filters to see if they're soaked with that shit...

In line fuel filter clean?

OMR

Air filter is good. New plugs also when I noticed the miss. Float levels are all good. Have good quality in line fuel filters.

I know, I know. It was running fine. I shouldn't have touched it. Just wanted it to be as perfect as possible. Could the combustion chamber cleaner have dislodged some crap that is stuck in the valve? The tops of the pistons are really clean now. Or is it just coincidence and something is stuck in the pilot system of #2 carb. It's hard to tell, but it seems to run fine wide open.

Definitely possible some fine ass crap got into the jets and such...

If stuck in a valve... hmmm... One way to check would be compression and leak down testing I guess...

I 'd stick with your carb theory myself...

Sorry to hear about this but as Plummen and Larry have informed me numerous times (actually screamed "What the hell you do that for dumbass") leave it the hell alone for you have it dialed in already... Now go ride the balls off that thing and quit dickin with it....

Damn, my mentors can be a tough crowd at times... :laugh:
:laugh: :laugh: :laugh:

OMR

FRACKING BATTLE FRACKIN STAR GALFRACKINACTICA FRACKIN LIVES FRACKIN ON.DONT FRACK A FRACKIN ROUND.
HAHAHAHAHAHA:woohoo: :woohoo: :woohoo:

Can I tell if it's a problem with the pilot system buy running at high rpms for a while, then hit the kill switch and pull in the clutch? Then pull over and check the plugs?

carb junk.....do you run a fuel filter...strange that it only one carb....pull the carbs...and inspect each piece of just that bowls jets ...passages..i think somehting may have got wedged in a jet...

did i miss it...do you have sparkles on that plug/wire....

Have good spark. Switched #2 & #3 wires. Both 2& 3 pipes were cold. Then I switched in a new used coil, checked sparks. All good. #2 pipe still cold and plug black and wet.

Have good gas filters.

so the compression is close like before on that cyl...you got sparkles.....you got a good plug....wet plug..ie..gas getting into that jug..:S ..try a b7es in that cylinder for a few miles... a new one...let it sit over night with all four of the plugs out and gas off and vented area....then try three b8's and a b7 in the 2 cyl......dunno.....i can reason o.k but i'm no tech guy...if all is correct as you've checked it should at least be firing...2nd scenerio ...check the valve clearances especialy on number #2...good luck....it'll solve and you'll be riding to the show..98% percent of the time these old girls get running again imo...

Try turning the pilot air scew out a full turn on the cylinder thats running rich.take it for a run let it get nice and hot then check the plug.I think that youll find each cylinder has got to be tuned to its proper air/fuel ratio.these old air cooled engines have inconsistent cylinder temperatures and each cylinder has to be tuned with the carb thats giving it gas.

Go for a short ride of a couple miles, check and see if that header is still cold or if it heated up some. If it did, probably a clog in the choke circuit (hole in the bottom of your float bowl). Just figured out thats why my #2 was cold...Header would be ice cold when idling or revving but after a ride there was evidence that it was sometimes firing (warm, plug changed a little). The plug told me nothing - it would be wet sometimes and dry others but it all went away when I cleared the choke circuit :whistle: Good luck... worth a try at least