Slight Engine Popping · Aussieveedubbers

paslow22 · 1 Dec 2018, 7:32 pm

Hi,
When I come off the throttle down a hill for example the engine gives out some slight popping noises.
My idea would be carb mixture settings.

I'm running a 1915, and twin 40mm Empi's.

What do others think????
Thanks.

beetleboyjeff · 2 Dec 2018, 7:59 am

An exhaust leak will often cause that

paslow22 · 2 Dec 2018, 8:41 am

beetleboyjeff wrote:An exhaust leak will often cause that

Thanks,
I'm pretty sure there are no leaks but I will double check.

REDKG · 2 Dec 2018, 2:12 pm

Inlet leak

paslow22 · 2 Dec 2018, 3:57 pm

REDKG wrote:Inlet leak

When I changed the manifolds using new gaskets I'm sure I tightened them all up tight, I'll double check.
Hope not, because it's a bugger to get to No.3 nut.

Thanks

vw54 · 2 Dec 2018, 3:58 pm

if its popping it is unburnt fuel in yr exhaust I would be checking the jetting

paslow22 · 3 Dec 2018, 5:48 pm

vw54 wrote:if its popping it is unburnt fuel in yr exhaust I would be checking the jetting

To rich or lean?

vw54 · 4 Dec 2018, 7:55 am

I would say rich

You need to have an analyzer up the exhaust

the EMPI carbies are not very good as well.

grumble · 4 Dec 2018, 12:27 pm

An exhaust system with insufficient back pressure will also cause popping on deceleration, this was fairly common on the extractor systems with the hot dog muffler which would do a couple of pops and then an almighty boom and flame out of the pipe. Very effective at night.

paslow22 · 4 Dec 2018, 7:19 pm

vw54 wrote:I would say rich

You need to have an analyzer up the exhaust

the EMPI carbies are not very good as well.

Ok Thanks, The empi's were on the car when purchased.

paslow22 · 4 Dec 2018, 7:23 pm

grumble wrote:An exhaust system with insufficient back pressure will also cause popping on deceleration, this was fairly common on the extractor systems with the hot dog muffler which would do a couple of pops and then an almighty boom and flame out of the pipe. Very effective at night.

Car has a Fatboy muffler, maybe the cause?, I guess I have a few things to check up on. Keep me busy anyway.
Thanks,
Darryl

paslow22 · 6 Dec 2018, 8:23 am

paslow22 wrote:
grumble wrote:An exhaust system with insufficient back pressure will also cause popping on deceleration, this was fairly common on the extractor systems with the hot dog muffler which would do a couple of pops and then an almighty boom and flame out of the pipe. Very effective at night.
Car has a Fatboy muffler, maybe the cause?, I guess I have a few things to check up on. Keep me busy anyway.
Thanks,
Darryl

Latest, Disconnected all carb linkages and re set carb and air/ mixture and it seems to have solved the popping.

Thanks for all the input.

Darryl