Can not figure out this decel pop

[Mccd06]

I have a 1994 Honda Shadow Vt1100c. I bought the bike about a month ago and it only had 8000 mile on it. I know it did alot of sitting during its lifetime. It had some decel pop on the rear cylinder with the stock exhaust. When I got it I changed the plugs and changed the oil and fuel filter. I pulled the carbs and rejetted and cleaned well. I put some cobra drag pipes on it. I have checked and tested the plug wires, ignition coils and pulse generator. I still have the decel pop. Plus I have to move my pilot screws on the carb to (Front:2 1/2 turns-Rear: 4 1/2 turns) just to get it to run decent with lower decel pop. I have done everything I know how to do and have not solved the problem. I would appreciate any help with this.

[93gc40]

DECEL pop is cause by lean fuel mixture. Lean could be due to air leaks, fuel blockages or too small of jetting. IF you are at 4 turns out or more on the pilots. You need to rejet. By the way at 4.75 turn the screws will fall out. If you are at 2.5 front and 4.5 rear your carbs are severly out of Sync. Build this tool and fix that issue BEFORE rejetting. $1.55 Carb Sync Tool by Marty Ignazito on your bike the pilot screw will end up within 1 turn of eachother when correctly adjusted.

[John Hopkins]

when you cleaned the carbs did you strip and clean the air cutoff valves..and did you replace all the o'rings..also if you split the carbs when you cleaned them you will have to rebalance them..if you changed the pipes you will need to rejet..

If you have the California model you should change all the spring clips to hose clips..the spring clips bed in and stop gripping and let air in.

John.

[Coop]

It could also be an Exhaust leak.... I think. I know if you have a leak it pops, just not sure about if it's decel or all of the time...It is worth a check after the carb sinc!
Good luck, keep us posted.

[mattyo]

Yeah, I'd +1 on the carb sync first thing. Put both your a/f screws at 2 turns out and sync them. If you still have popping from the rear cyl, as said above, check for vacuum leaks on the carbs, exhaust leaks, (that's new to me), and if no fault is found then size up your jet. Just my 2 shillings.

[93gc40]

DO NOT adjust anything until you know for a 100% fact there is not dirt in the fuel system from the tank to the heads. AND that there are no Air/Vac leaks, intake boots, seals, diaphram, Smog Crap and exhaust gaskets. If there are any air leak in between the airbox and the heads, it is IMPOSSIBLE to properly Sychronize the air/Fuel mixture FLOW through the motor.

[cl65ame]

+1 on the air leaks and the Carb synch. When you installed the aftermarket exhaust did you replace the crush gaskets with new ones? An exhaust leak at the head connection will most certainly make your exhaust pop.
Check all of the boots where rubber meets metal.

[Mccd06]

Thanks for all the suggestions. I will work on these things in the next few days. Built my own car sync tool as recommended just waiting on the adapters. In the mean time I will check for leaks before I sync anything.

[cl65ame]

The synch check is fast to do. My setup is hanging in the garage. I can pull the bike in, hook it up and test the synch in under 10 minutes.
Adjusting it is another matter. I have to pull the tank to get to the synch screw. I have never been able to find a tool to do it without pulling the tank.

[Yooper]

Try putting the stock pipes back on and see if it's still there. I have the Cobra drag pipes as well and no matter how much fine tuning we did there's still a random pop on decel. Stage-1 re-jetted, sync'd, K&N air filter, etc.....and it's still there. I think it's just the nature of the beast with those pipes.