Popping sound on deceleration

[gargantua]

Hi,

 

Mech just replace some parts on the bike engine(gn250). Now I experience a popping sound from the exhausts on deceleration. I need to throttle harder to receive the same power from the engine. Any idea what could be the cause? THanks.

[simon29tan]

What did you change? or tell the mechanic to do?

 

The pop sound is actually 'good'. Many racing bikes also got popping sound when they close trottle. Meaning to say your carb tuning is very the powerful for POWER, aka the carb is now tuned to increase the FUEL to air ratio>> more fuel!!

 

The sluggishness you feel is due to the extra fuel that is going into your engine.

You fuel consumption will 100% be higher from now onwards.

 

There lies the basic law of carburetor....at small trottle....less fuel is better not more! However many mechanics always like to play punk with the bike owner, partly because many owner always complain bike NO POWER. So the mechanic just tune more fuel into your carb at low speed, hoping that you will feel the power.

[zelda1031]

yo i hab e totally same case wif u

juz chain mine timing chain & some bearings

 

now mine bike keep having poping sound when i deceleration...

& i feels like mine bike got no pwr .....

keep die bike when i juz start e bike somemore ...

[gargantua]

I did a top bottom end overhaul. Also the the rubber thing between the carb and engine block.

[gargantua]

The bike doesn't feel strong when idling or when on the move. Like you must give it more throttle. Also not as cheerful as before. Any suggestions what to check. Its very noticeable to me, since I am very familiar with the bike, the popping is definitely more that before the service. Any suggestion on what to check?

[ulysses_sc]

Popping during deceleration is a symptom that the engine is running lean (too little petrol). This may be caused by:

 

1. too lean jetting

2. air leaks

3. some sort of emission control gadget (if your bike is equipped with one)

 

I would suggest you check for air leaks around the carb boots, then work on the jetting.

 

To the other misguided poster:

 

popping during deceleration is NOT a good sign, nor is it POWER. Too rich jetting will cause the bike to not rev properly, like it's gargling on too much fuel. Too lean jetting and your bike feels "flat", like no power.

[archenemy]

sounds like backfiring to me...

 

when did you last change your sparkplug? it might be a cause...

 

if not..it should be your caburetor...

 

ask your mech to tune it to reduce backfiring..

[Guest enHANZed]

the last time my super 4 had that popping sound ...i put it on a dyno run...at full throttle got fire come out of the exhaust man ....and the graph is very bad ....after tuning a bit ...no more popping sound and BHP increase by almost 10

[Aalex82]

Originally posted by ulysses_sc@Jul 16 2006, 12:00 AM

Popping during deceleration is a symptom that the engine is running lean (too little petrol). This may be caused by:

 

1. too lean jetting

2. air leaks

3. some sort of emission control gadget (if your bike is equipped with one)

 

I would suggest you check for air leaks around the carb boots, then work on the jetting.

 

To the other misguided poster:

 

popping during deceleration is NOT a good sign, nor is it POWER. Too rich jetting will cause the bike to not rev properly, like it's gargling on too much fuel. Too lean jetting and your bike feels "flat", like no power.

 

is true that popping of engine isn't very gd..

more fuel ratio compare to air doesn't mean more power..

u burn alot of fuel but not enough air for combustion oso no use..

[CarroTT]

check your exhaust for any leaks

and then check ur exhaust valve for leaks

[Zer0]

What he said, most common cause is airleak in the exhaust, either around the exhaust ports where header bolts on or around where the end can bolts on.

 

That explain why it has happened more since you had the top end done as header must be removed for this and might not have been put back on properly. Generally you would replace port gasket while you had the header off as they cost like $1-2 so may as well!

[Options]

after my friend replace his gasket at the header.... e irriating popping sound during deccelerating dissapear haha...

[ET]

it can be your cam also...

[boofeng]

hmm. yeah what ET says might be the thing... my engine was running 10 degrees retarded, and i had popping on decel. then recently i had it opened up and re-timed with the service manual, and now there're no more pops on decel, and revs up much faster.

 

if the guy who opened up your engine didn't set the cam timing back properly, it might be causing your pops.

[jonse]

but new bike also will like tat.. how?

[Angel_of_sin]

Originally posted by gargantua@Jul 14 2006, 11:07 PM

Hi,

 

Mech just replace some parts on the bike engine(gn250). Now I experience a popping sound from the exhausts on deceleration. I need to throttle harder to receive the same power from the engine. Any idea what could be the cause? THanks.

tuning too rich....

[Raptor]

My CBR pops when I downshift at high rpms on the track.

 

My DRZ pops most of the time when I close the throttle to up shift through the gears. And it pops like crazy when I downshift at high rpms on the track.

 

But both bikes do not suffer a loss of power during acceleration. By the way, both bikes have Yoshimura systems on.

[spenx75]

Originally posted by Zer0@Jul 21 2006, 04:36 PM

What he said, most common cause is airleak in the exhaust, either around the exhaust ports where header bolts on or around where the end can bolts on.

 

That explain why it has happened more since you had the top end done as header must be removed for this and might not have been put back on properly. Generally you would replace port gasket while you had the header off as they cost like $1-2 so may as well!

Agree with Zer0. If the carb was not tempered with, check the headers gaskets 1st cos its the easiest n cheapest step. . . most mech will never bother to replace the copper gaskets. . . its probably crushed and air is leaking from there. If not, it will probably be ur top end job. . .

[druid82002]

i got popping when i close throttle and just let the bike cruise on the gear its at ....

but no probs when decel or accel

 

any idea?