Topic: popping after air filter change

[gold72]

I finally got my new airfilter (stock replacement), my bike was running rich and constantly fouling plugs etc before the new airfilter.

I popped in the new filter, new plugs, new oil and it is running great aside from the fact it is now popping on deceleration, which it didnt do before today.  My question is do i need to rejet now that I have a clean airfilter in there, or should I start tinkering with the screws on the carbs

pulled my plugs and they look normal..

My bike is a 72 cb500

Its sounds kind of cool when it pops though, but is it harmful for the bike to be popping like this?

thanks, I am almost there, we only get a couple of months of good weather up here in Vancouver,

Its sounds kind of cool, is it harmful for the bike to be popping like this?

[Hush]

Not sure about harmful mate, I know we used to get told off for coasting down steep hills and turning the ignition off and on to make our bikes pop when I was a young fellah.
No expert on your air filter problem but after reading posts on here about changing back from pods to air box etc it may be that your jets are now wrong for your new air supply.
Hold on and a real expert will be right along after I bump your post he he.

[CBJoe]

Make sure that you don't have any exhaust leaks (ie. at the clamp between the muffler and head pipes, or anywhere else).

Barring this, you went from a rich to a lean situation.  Lean can cause the pops, so maybe it's time for some mixture tuning.  I'm sure someone else will chime in with more specific info.

Cheers...Joe

[misterpunch]

I wouldn't advise screwing around with the screws arbitrarily as I don't think it will help anything unless you get really lucky.  I had a similar problem and fixed it by tightening the clamps on the carb boots.  There was a small air leak and it was noticeable in the performance.   

[gold72]

Thanks everyone
I tightened everything up to make sure, I figure it has to do with my new air filter.  Previous to the filter it was running really rich, my first ride out with the new filter and its is popping (also sounds like the exhaust that is popping is chugging a little louder than the other three)

I just swapped out my old air filter with a new air fiter, I didnt change from pods
At least its not rich anymore..

[TwoTired]

What is your idle air bleed setting?

If you have exhaust header gasket leaks, simply tightening them may not fix it.  These are crush gaskets.   They don't spring back after being crushed.
Did you take off the exhaust without replacing them?  Did the PO?

Hopefully, the air screws will take care of the problem.

You have the stock 4 into 4?  If only one pipe is popping, you may also have slow jet restriction.

Have you vacuum balanced the carbs?

[gold72]

TT

the airscrews are 1 turn from seated

My exhaust is stock 4-4, not sure if one pipe or both are popping on the right side, left side is not popping

I havent vacuum synched the carbs

I was just out tinkering with the air screws, didn't seem to help

wouldnt the popping have been there before my new filter if it was a slow jet restriction

I am still pretty green and really appreciate the help

I am not sure if the pipes have been removed by the PO

[TwoTired]

Sync the carbs first.

wouldnt the popping have been there before my new filter if it was a slow jet restriction

Maybe, maybe not.  If one jet was more restricted than the others, they would all be too rich to pop.  Now one or two is lean enough to pop....maybe.

What do the spark plug deposits look like?  Do all four appear to have the same deposit pattern?

Is this popping on decelleration or just idling?

Have you done the whole tuneup process?  (every 3000 miles)  Or, just playing the whack-a-mole game?

Do the mufflers have extra holes in them?

[gold72]

I decided to tune it up myself, adjusted cam chain, my valve clearances were pretty spot on, did the points, changed the oil/filter.

I changed my oil today as well to amsoil syn 10w40 from mineral oil /changed oil filter and swapped out my air filter today, was excited to taker her out and pop pop pop

I think it only pops a decel, the third pipe is chugging more so than the other three for sure

which extra hole do you mean? it has that little hole on the bottom of all 4 pipes

The spark plugs look good, for the first time in a long time, kind of a choc brown, compared it to dans mc chart and they looked good (and are all pretty uniform in appearance)

[TwoTired]

which extra hole do you mean? it has that little hole on the bottom of all 4 pipes

A bike this old could have extra rust holes.

The spark plugs look good, for the first time in a long time, kind of a choc brown, compared it to dans mc chart and they looked good (and are all pretty uniform in appearance)

Swap the popping cylinder plug with one that doesn't.  Does it follow the plug?

If it only does the popping on some cylinders, there is clearly something different among the cylinders.  If it's not carb sync, then you have to find out what that is.  Are the carb boots all in good, non-leaking condition?

[gold72]

no rust holes, the pipes are in great condition

I will try switching the plugs over, but they are brand new

The carb boots are in good non leaking shape

I will have to sycnh the carbs asap just need the vacuum gauges

Is the popping harmful, cause I do kinda like how it sounds after all

thanks again

[Hush]

Looks like you have invented the first Honda blow-off valve, watch out the young hoons will want it for their GTIR's and Subbies!

[gold72]

haha, the only thing about the popping that worries me is if it is running lean, but my plugs look good..

[Johnie]

Well, my KO has new plugs, new condensors and points, clean carbs, valves adjusted, new plug wires and ends, timing, sync and air screws adjusted to the manual.  Mine pops a little only on deceleration.  But you know, this 1970 runs like a top.  I mean never a miss or hesitation.  Idles nice which is hard to obtain sometimes on these 4 carb / 4 throttle cable systems.  I feel pretty lucky it runs so well.  I really do not think it will cause any problem to pop.  And I agree, sounds sort of cool.  Reminds me of many of the old school bikes I drove in the 70's.

[gold72]

for sure it has an old school sound, mine is not hesitating or missing on accel either, I think I am going to leave well enough alone for the time being

Going to run some seafoam through her and see if it is a sticking low jet making it pop, if not then it is popping until the fall 

just out of curiousity I have adjusted the valve clearences myself for the first time and I think I got it spot on, would valve clearance be a possible cause for this? and if so how?

Thanks for all the help

[TwoTired]

VACUUM SYNC YOUR CARBS!
The procedure is listed in the Honda shop manual for a reason, you know.  It's not just to keep the techs busy.

The popping is explosions in your exhaust.  When your rusting pipes get thin enough, holes will appear sooner.

If your valves are adjusted too tight, the popping could be leaking exhaust valves.

[gold72]

TT, will do going to check my valves tonight and if that doesnt do it I will go buy vacuum gauges
didnt consider it was doing damage to my pipes

thanks

[holdfastgreg]

I speculate the popping noise is from backfire.  Its from unspent gas fumes igniting in your exhaust.  A lot of turbo'd cars will spit 3-10ft flames from their exhaust from down shifting or braking  This isn't a bad thing generally, unless your marginally flooding your engine and losing unspent fumes into the exhaust.  If this happens for a period of time you're exhaust will smell like rotten eggs.  Not sure if this helps....