back firing and popping in #1 carb only

[rainman]

not sure what the problem is but I hope it is not what I think it is.
the problem is at about 1500 rpms the #1 carb front right carb is popping i have checked the vacuum and no leaks also put a new plug in still the same.  The only thing i have not done is to and see it might be out of sink.
any help would be good

Thanks in advance   

[Chrisj CMA]

not sure what the problem is but I hope it is not what I think it is.
the problem is at about 1500 rpms the #1 carb front right carb is popping i have checked the vacuum and no leaks also put a new plug in still the same.  The only thing i have not done is to and see it might be out of sink.
any help would be good

Thanks in advance   

Out of SINK huh....lol   Carburetor synchronization only is important for idle and initial accelerations.   Once all six slides are moving sync is a non issue so the popping at 1500 is most certainly caused by something else.  Id recheck the vacuum plug on that intake nipple.  Sometimes they look good but are dry rotted and leak.

Also did you check the exhaust, lose header nuts can cause this. 

And did you check all the intake runner clamp screws?

If all that checks out Id run some strong techron or B-12 and see what happens

[rainman]

hep header nuts are tight and intake clamp screws are tight. one thing i forgot to say is that if i pull the chock about half on it goes away

[Chrisj CMA]

hep header nuts are tight and intake clamp screws are tight. one thing i forgot to say is that if i pull the chock about half on it goes away

What did that spark plug look like when you pulled it?  The choke (enricher) significantly richens up the mixture, if #1 is running lean it would like the enricher so maybe all you need is an air screw adjustment.

[rainman]

spark plug looked good but i did replace it with a new one

[Punisher]

Have the o-rings under the carb tubes ever been replaced?    Bolts on the carb tube snug?   Be careful, I think the torque on those is very light, like 6-7 ft lbs.

No sign of leakage around it (a yellow/brownish residue)?

[pocobubba]

Check the slide diaphragm for a tear or hole

[rainman]

Have the o-rings under the carb tubes ever been replaced?    Bolts on the carb tube snug?   Be careful, I think the torque on those is very light, like 6-7 ft lbs.

No sign of leakage around it (a yellow/brownish residue)?

Punisher O-rings have never been replaced but there is no yellowish brown on heads did check to see if they had loosen up but they were tight going to run some teckon b-12 and see if that makes any changes. if not I am in the work of making a tool to reset the carb.

[rainman]

Check the slide diaphragm for a tear or hole

where the hell is the slide diaphragm at never heard of that animal
 

[signart]

Actually I think he means vacuum piston. The rubber part under the chrome cap, then black cover on top of each carb. Easy to tear or get misaligned when fooling with it. Good thing to check, will cause popping. Real cheap too, you'll be very careful with them after you buy one.

[pocobubba]

You are correct Signart vacuum piston is the proper term . I've never had problems on my Valks but have had problems on other bikes , same symptoms .

[rainman]

now I know what you are talking about will have to check it should be ok never have had the caps off but I guess that don't meant it couldn't be mad