popback backfire

[drowningbird808]

my bike backfires through the carbs when its cold under light throttle. it sometimes does it when it warm too. also on decel, theres a lot of popping . theres also a rattling noise coming from the head. am i looking at a valve job or a timing chain?

[dowdy80]

hey pal, on deceleration the poping is just burning excess fuel being burnt, as you decelerate is stops drawing in air yet it still seems to drag more fuel than air, this is completely harmless, but if it is backfiring then thats a problem, as for the knocking, it sounds like your valves knocking, just take off the head and check the clearance from the shim. let me know what you decide to check on mate. im no expert but im just going off what i know and what it sounds like

[robfriedenberger]

  On the noise post a video to youtube and link it here well take a listen and tell you what we think but you might want to check the valves.

[jacob92icu]

Just like dowdy said, back firing under deceleration is normal. Also, I am sure that your tick coming from the header area is probably the usual gs500 tick due to the floating cam chain or something of that nature. It has something to do with the cam chain being in the middle instead of on one of the sides.

The fact that it pops while idling means you probably need a rejet is my guess, running to rich or something. Good luck figuring it out!

[Janx101]

Just thought of a thing.....

Not having a go at drowningbird ... But over time and recently.... There has been a fair few new GS500 owners ... All worried about noises and bangs and pops etc .... And ok some of them are proper serious issues....

But I remember getting mine a few years back and being concerned what it sounded like with different things and noises... Got on here and got some advice, but also found someone nearby with a GS500 too that had done some of their own work on it... And had a chat while the bike was idling and some light revving and a ride ... To be told that a lot of the noise .... Was GS500 yep that's what it is! Noise ... Normal!

This bike is a bike for sure.... But your mates cbr600 sounds different, the other guys Ducati monster 620 sounds different, your cousins XR450 sounds different.... Same and same works! ... Same and different not so much!

Could be issues for sure.... But until familiar with 'normal' .... How do you tell? 

[Meuryn]

Had the same problem, along with quite a few other people. There's a thread on it where it was termed a 'lean misfire', the solution either being adjustment of the idle circuit screws, carb cleaning or rejet  Link below

http://gstwins.com/gsboard/index.php?topic=66633.0

[BockinBboy]

+1 Meuryn beat me to it

The mentioning of the backfire in carb, and popping on decel leads me to believe you are lean all around - but to figure out why we need to know your general location, what year of bike, exhaust, air filter, and carb jetting you have.  If its all stock, then we can look to some minor carb adjustment (like the mixture adjustment screw) or minor jet cleaning, or something that coincides with 'not getting enough fuel for the amount of air' (possible kink in fuel line, etc.)... If its not stock, it could point right at the issue, or point us in the right direction.  Does it do it in both carbs or just one (if so, which one?).

Some popping on decel is normal with stock setup because they are lean from the factory, more especially so on the newer models because of the PAIR system - but add your backfiring in the carbs along with the decel pop... its definitely leanness issue to correct.

- Bboy

Edit: On the rattling around the head... well, tough to help with that sort of thing without hearing it on this end of the screen, unless there is something very tell tale in a description.

[Crasm]

Mine used to backfire in the left carb at low idle after i fitted the delkavic ,since the lunchbox and rejet its not happened since.

If yours is standard try backing the mixture screws out half a turn on each carb to richen the mixture it may be all it needs 

[Meuryn]

+1 Meuryn beat me to it

When do I get my prize?   

[BockinBboy]

Lol, you'll 'feel' it when the OP posts back he found the problem and its resolved   



- Bboy