Author Topic: Carb synch issues (Read 4414 times)

Cruisecontrol · « **on:** May 31, 2006, 04:45:37 AM »

I have hit a bit of a snag.
I've got an '03 B12 and am running a full Hindle system, a stage III jet kit, K&N pods and ignition advancer. After the rejet the bike was running very strongly but was very lumpy at idle. I had never synched my carbs so I thought it would be a good idea. I knocked up a po' mans carb sync tool and adjusted things from there as they seemed to be way out.
I took it for a ride today and it goes like a POS. Stumbles on acceleration no matter what the revs or gear I'm in, is backfiring and has lost a stack of the power I had before the synch. I had a look at the plugs and #3 and #4 were very black but #1 and #2 were fine.
I pulled things apart again tonight and resynched the carbs but they seemed pretty much ok.

Any ideas on a solution or have I just missed something very obvious?

solman · « **Reply #1 on:** June 07, 2006, 01:05:08 AM »

I know that people talk about making carb sync tools, but I prefer to just spend the money for a mercury synchronizer. I've had my carbs out of sync before and it shouldn't cause plugs to go black. I would start out with a fresh set of plugs and go from there. I've had a few screwy issues with plugs on my 03 B12 in the past. The last time my bike was running bad, all I did is remove and re-install them. No problems since then.

99er · « **Reply #2 on:** June 09, 2006, 09:27:01 AM »

I'm cheap and have used homemade tools forever. My pickle jar brake bleeder is still the best, with help from car vacuum nearby. The carb sync tool, made from Home Depot tubing and a yardstick, with synthetic fork oil, worked fine but only could hook-up to two carbs at a time. The mecury tool was cheap and is a relief.
You compounded your problems and really need to make sure your sync is perfect. Buy a tool.
Marc/Atlanta
'99 B12

Daytona · « **Reply #3 on:** June 14, 2006, 10:22:40 AM »

Hey Cruisecontrol! Did you get this resolved? If so what was it?

rspector · « **Reply #4 on:** June 14, 2006, 12:15:14 PM »

I have found that if your carbs are way out of sync that you can foul out plugs, if you don't want to spend the money on some vacuum gauges (which i think are better then the merc gauges because you can't spill any mercury, which is a bitch to buy these days)you can pull the carbs off and do a bench sync by getting two of the smalls drill bits you can find, and making sure the gap between the valve on the back of the carbs and the carb body are the same all the way accross, that will get you with in 1/3 of an inch.

JayRo · « **Reply #5 on:** June 14, 2006, 11:18:22 PM »

There was a great thread about 10 months or so ago about making your own carb sync tool. It was basically making a U tube manometer out of clear vinyl tubing, and using water as you measuring liquid. Probably less than 5 bucks at the hardware store for tubing, and it is just as accurate as any specialized tool you could buy for the job. It was a snap to do. I couldn't believe how out of sync my carbs were.

I am not sure if it was archived or something.

Jason

Cruisecontrol · « **Reply #6 on:** June 15, 2006, 05:22:58 AM »

Quote from: Daytona

Hey Cruisecontrol! Did you get this resolved? If so what was it?

Long answer, yes with an if... Short answer, no with a but...

The fault is very intermittent so it is hard to figure out what the problem is. One day it will be running perfectly and the next it is dropping cylinders and losing power, sometimes doing both during a ride. I have put in a new set of plugs tonight so I will see how that goes over the next few days.
I have checked and rechecked my carbs but cant come up with any reason for the large variation in performance.

chevsuz12 · « **Reply #7 on:** June 15, 2006, 09:14:53 AM »

I would check your diaphragm's, the rubber may have gotten pinched, or torn and you could be getting a vacuum leak.