Hi Everybody,

I've got a miss on #2 on my '82 Seca 750. I can tell as it runs rough and the exhaust pipe never heats up. I have checked and swapped the plugs. Pulled the plug out still on the wire and saw the spark, compression tested all and they were all the same, Pulled the top cover and checked the chain (Good), Chain Tensioner (Also Good) and the valve clearances and they were also good. Just recently I did rebuild the carbs so I thought that maybe it was not getting any gas but the plug does get gas on it. Basically it seems that once the plug is in, it stops firing. The only thing I can think of is that the spark might be getting weak but it does look strong.

Any Ideas?

Thanks.

Well its not the ignition. I flipped the wires and plugs between #2 and #3 and the problem did not move.

I also noticed that the #2 carb was seeping gas so I think I found the problem. I tapped on it to see if it was a stuck float but no luck. I'll pull the carbs off tonight and see what the deal is.

I have the same problem with my GS 850 at the moment. My problem is the air/fuel mix as I have previously mucked about with the pilot screw. I have just rebuilt the bank of carbs and I am just waiting for time to retune and balance them using my colourtune plug and morgan carbtune gauges.

Did you check the plug caps? When you swapped the wires, did you just unscrew them from the caps?

Are you getting spark? (i.e. take out plug with wire connected, turn off fuel, and just crank it over to see if plug is sparking.

Finally do you have Colortune? It might be the mixture setting. I had exactly the same problem - but my fuel mixture was off. Colortune fix it right up.

I've got good spark, I'm pretty convinced its the carb. I looked into it a little bit (didnt have much time last night) and the plug is getting coated with gas. I should have time tonight to yank them off and open that carb up.

Colortune? Never heard of it. What is that?

It gives you a window into the cylinder...
No color means no flame...
Yellow or orange is a little rich
Whiteish is to lean...
Blue is just right...

http://www.carbtune.com/colortune.html

Thanks for the info on the color tune.

Update:

I pulled off the carbs and found crud in two of them. Spent some time cleaning them out and putting them back together. Set it all up and started it up. Fired up to an idle and ran real smooth. Shut it down as I was in the garage and didnt want it to run too long. Pulled it out into the driveway. Now when I pulled the tank off, I thought "gee, this seems lighter then it shoulde be, it should be almost full". I didnt investigate this little factoid and went on with my life. When I fired it up again out in the driveway and reved it up, I was greeted with a real nasty surprise. I had the vent tube off for the crankcase and I got a very impressive stream of gas and oil to shoot up my pants and all over the place. Looks like I found where the gas went. At least one carb was just dumping it when I was ideling the bike trying to troubleshoot it. I guess better in my pants then filling up the airbox. That could have been real bad. I didnt want the stain to spead down the driveway so I ran into the garage and grapped a big scoop of what I thought was floor dry and ended up throwing a bunch of cat food all over the place. At that point I just gave up and went and took a shower before things got worse.

So one oil change later, the bike seems to run real smooth now. All cylinders are firing well. I have not rode it yet as I want to change the oil again just to flush things out. I also still have the electrical problem I need to look into.