Carb backfiring “Weber ICT34”

[Gabs]

After some help as I have a backfire/pop coming through my LH carb and runs flat at 2000rpm especially when I hit the inclined roads. I have replaced all plugs, leads with cap rotor arm and just cleaned LH carb as seen some info on an idle jet block. It runs nice on tickover but when you blip throttle it backfires on that LH carb. Don’t seem to have an air leak as sprayed all around inlet and no change in engine note.
Should I re-check valve clearance on LH bank ?
I will take the plugs out and check again.

Any help appreciated please.

 

[K@rlos]

Are the carbs balanced?

 

[67panel]

Blocked accelerator pump.

 

[Gabs]

Are the carbs balanced?

Yes all balanced correctly. I read some details with checking the head bolts and making sure there torque ok as when the engine warm it’s not backfiring.

 

[Gabs]

Blocked accelerator pump.

 

[Gabs]

Blocked accelerator pump.

Hey 67 Panel, is this a common fault with ict and would that cause the symptoms ?

 

[67panel]

Can happen on any carb, check if it squirts fuel when you open the throttle. bad diaphragm ,stuck ball valve or blocked jet are things to check and yes that will cause it to pop back.

 

[Gabs]

Can happen on any carb, check if it squirts fuel when you open the throttle. bad diaphragm ,stuck ball valve or blocked jet are things to check and yes that will cause it to pop back.

What’s your thoughts on this video I just done of the carb ?

 

[gas1man]

It probably is not the problem, however sounds to me like petrol starvation.
I'm sure some one will point you in the right direction.

J & P

 

[Gabs]

It probably is not the problem, however sounds to me like petrol starvation.
I'm sure some one will point you in the right direction.

J & P

Thanks for details I had someone mention my. Needle valve is passing fuel so checked the valve and it has wear so I asked Michael Leather some details who good with webers ICT. Fingers crossed as it’s doing my head in

 

[james_stan]

Valve clearances? - worth eliminating

 

[Gabs]

Valve clearances? - worth eliminating

Done all that James looks like issue with float and needle valve which is causing the over fuelling. Ordered a new service kit now.

 

[Wannabay]

Done all that James looks like issue with float and needle valve which is causing the over fuelling. Ordered a new service kit now.

 

[Wannabay]

A mate had a not dissimilar problem, turns out the float had degraded and become spongy soaking up petrol

 

[Gabs]

A mate had a not dissimilar problem, turns out the float had degraded and become spongy soaking up petrol

Hey Wannabay funny enough that’s seems to be issue float should weigh 11grams and mine was weighing 12.90 so looks like same issue so now ordered a carb serving kit.