[covergre]

Hi, I was hoping someone out there could help me with a little problem im having. When riding down steep hills under engine breaking my bike is backfiring quite badly. What would cause this problem and how do i go about fixing it?
Thanks again.
Greg C

 

[t-rex]

higher gear

 

[Redracer]

is the machine completely stock? What elevation are you at? Is the machine carbed or fuel injected?

 

[covergre]

Hi Redracer, the bike is fully stock no mods done, bike is only about 300m above sea level most of the time and the bike is carbed.

 

[TRX2fiveO]

Engine back fire is cause by unburned fuel build-up when your ideling down hill in a lower gear eg. 1st or even 2nd your dumping fuel into the engine at the same rate as idling. when the RPMs increase but not due to throttle you are still adding fuel therefore causing the engine to ignite the extra fuel resulting in a back-fire.

 

[covergre]

Hi, thanks for the info TRX2fiveO, can this undurned fuel be reduced by making adjustments in the carb? or is it something ill just have to live with.
Thanks

 

[TRX2fiveO]

I'm not sure on that , if your brakes work good you can neutral it down and just rev it up a few times as you are heading down, that should keep it clear, as far as any adjustments are concerned I can't come up with any good answer for you.

 

[Redracer]

If the jetting is correct, there should be no unburned fuel. Popping/backfiring while under engine braking is normal... It shouldn't sound like an automatic rifle but you are using back pressure to slow you. Just like a Jake Brake on a truck. If you are running rich would be the only reason I see for unburnded fuel.