KarTek Posted May 6, 2012 Report Share Posted May 6, 2012 Guys, sorry for starting a topic on what probably is a common subject. "Running on one cylinder" is not a valid search query so I didn't have much choice. The engine seems to be running on only one cylinder at idle but it runs like a scalded dog at anything higher. At idle, I only have one smoking cylinder but if I blip the throttle, I get a puff of smoke from the other. It pulls as strong as ever on the top end but lower RPM's act like someone has cut the ignition. Here's my troubleshooting matrix: Carb slides matched perfectly. Air screws matched. Spark plug wires swapped - no change. New spark plugs installed - no change. New float needles and carbs totally cleaned. What do you recommend I go after next? Thanks! Quote Link to comment Share on other sites More sharing options...
Dahl87banshee Posted May 6, 2012 Report Share Posted May 6, 2012 Compression test? Sometimes the compression is weak but builds up ok at higher RPMs Quote Link to comment Share on other sites More sharing options...
maskmanLS6 Posted May 6, 2012 Report Share Posted May 6, 2012 Guys, sorry for starting a topic on what probably is a common subject. "Running on one cylinder" is not a valid search query so I didn't have much choice. The engine seems to be running on only one cylinder at idle but it runs like a scalded dog at anything higher. At idle, I only have one smoking cylinder but if I blip the throttle, I get a puff of smoke from the other. It pulls as strong as ever on the top end but lower RPM's act like someone has cut the ignition. Here's my troubleshooting matrix: Carb slides matched perfectly. Air screws matched. Spark plug wires swapped - no change. New spark plugs installed - no change. New float needles and carbs totally cleaned. What do you recommend I go after next? Thanks! Sounds like the pilot jet or passages have an obstruction on that cylinder. Take out the pilot jet with a small straight screw driver and spray cleaner through the passage until you have cleaner coming through both of the exit holes in the barrel of the carb. There are two small holes in the barrel,,one is straight through to the pilot passage and the other is angled and also goes into the pilot hole. Once you get a spray coming through both then you can spray through the jet and then screw the jet back into the hole and try that. Also take out your idle air screw and jet. They can cause problems too and you do the same thing to them. The idle air jet screws out the same way and the air screw also needs to come out and spray through the passages as well. I just had the same exact problem not long ago. Quote Link to comment Share on other sites More sharing options...
KarTek Posted May 6, 2012 Author Report Share Posted May 6, 2012 Thanks for the replies! Compression should be good, it had a recent top end rebuild. I'll check that and the carb jets. Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted May 6, 2012 Report Share Posted May 6, 2012 I've seen this twice before on my bike. First time was when I first bought it.....the previous owner had aftermarket pipes and airfilters and stock sized pilot jets in it. So it was not able to suck down enough fuel to feed both carbs at idle.....but once I got on the gas hard enou for the main jet to open all the way it would feed both cylinders fine. Second time was when I rebuilt my cabs from a leak situation. Put em back on the bike and did a sync job BY SIGHT. Fired the bike up and it would only run on one cylinder......instant I blipped the throttle the dead cylinder would hop right back to life. Grabbed my sync tool from Jeff at FAST and damnit even though they both LOOKED to be matching one was off enough to not draw any flow at idle..... Turned that idle up and instantly solved the dead cylinder. Quote Link to comment Share on other sites More sharing options...
KarTek Posted May 9, 2012 Author Report Share Posted May 9, 2012 That makes a lot of sense, thanks! Quote Link to comment Share on other sites More sharing options...
jhwaldo Posted May 13, 2012 Report Share Posted May 13, 2012 quote name='KarTek' timestamp='1336522090' post='1343333'] That makes a lot of sense, thanks! Does it have a boost bottle cause a torn intake boot from a boost bottle will cause same problem. Quote Link to comment Share on other sites More sharing options...
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