Engine popping

Romer · Posted: January 19, 2009, 6:26 pm Post subject: Engine popping

I know I have seen this question asked before but I can't seem to find it. I just got my '72 xs2 running. Right cylinder was not firing. Carb issue. I put the carb back on fired it up and now I have popping at both exhaust - reving up and idling. I have no mufflers, just pipes. Carbs are rebuilt. pamco ignition. I have both carbs adjusted to 1-1/4 turns per book. What else?

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

i had to go to 2.5 turns out on the Pilots with open pipes and pod filters, otherwise i had popping on decel.

Romer · Posted: January 19, 2009, 6:42 pm Post subject: Re: Engine popping

did you have popping on acceleration too?

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

If you've got constant poping ..you could have blocked pilot jets.

Get a set of fine filters, dont rely on the one in the taps.

Take the carb's off again and make sure they are still clean..take out the jets and blow them through make sure you can see through the pilots.

Then also check for air leaks and splits in the inlet rubbers etc...

I was constantly coming across this problem, I'd fix it, then it would come back..then I bought some 30 Micron Super Fine Fuel Filters..and I cleaned the carbs for the last time..

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

no popping on acceleration.

Romer · Posted: January 19, 2009, 8:36 pm Post subject: Re: Engine popping

The tank was not in the best shape. I have an inline filter from Mike's. Where do you get the 30 Micron filters?

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

The Inline filters I use are from Briggs And Stratton and as such are designed for use in dusty, rusty and generally fubared environments Smile

y bike does slightly over 100mph maxed. So..they do flow enough.

www.amazon.com/s/ref=n...uel+Filter

They may have been 60 Micron. Which is almost certainly fine enough.

Funny I thought they were 30..mmm...

Anyhow 60 will do...RetiredGent. Uses 70 without problems.

I dont know how fine the "mikes" filters are...

Shannon60 · Posted: January 19, 2009, 10:14 pm Post subject: Re: Engine popping

exhaust leaks cause popping on decel also

Romer · Posted: January 19, 2009, 11:02 pm Post subject: Re: Engine popping

Thanks Jake, I'll try Lowes or Home Depot tommorrow. It is definatly an acceleration popping. I thought it might be an air leak in the carb area. I'll try the filters first.

Romer · Posted: January 25, 2009, 10:11 pm Post subject: Re: Engine popping

Well, New filter, cleaned carbs, adjusted pilots....still pops. Gonna try bigger mains and double check the timing.

jpowell · Posted: January 25, 2009, 10:34 pm Post subject: Re: Engine popping

I got the same thing, but didn't seam to show its head until after I re-checked the timing. What exactly is the popping? I only seam to see it on decel. The carbs could probably use a good cleaning, but maybe someone can explain theory behind this...

xsjohn · Posted: January 26, 2009, 12:51 am Post subject: Re: Engine popping

Decel popping...all other things being correct...not mentioned below...

..Usually assoicated with lean or clogged pilot circuit or improper mix screw settings.....sometimes too small of a pilot jet that can't feed the heavier demands of deceleration......and straight pipes or improper back pressure......or all......

xsjohn

Romer · Posted: January 26, 2009, 9:10 pm Post subject: Re: Engine popping

I slipped some baffles in the pipes and adjusted the timing. Still when it gets warmed up it pops on acceleration. It is spitting fire out when it pops. I think your right on the "all" xsjohn Smile

Guess I'll pick at it some more. Keep the suggestions coming. Thanks guys

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

Sounds to me like it may have an air leak somewhere.

Does it have points?

Spitting fire? ummm reminds me of a cam timing issue I once had, does it have a new cam chain or an old one?

Romer · Posted: January 27, 2009, 8:19 pm Post subject: Re: Engine popping

Pamco electronic ignition, Not sure of the state of the timing chain.

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