Stuttering 650s

[colin.carter]

Hi all.
I have 2 650s, one a full ground up complete restoration and the other a totally orig, 4000 mile time warp example - both are suffering from the same prob.

They are B2 and B3 models both with the vacuum petrol tap.
They both run and accelrate fine but on a steady throttle stutter as if they are running out, or being starved of petrol?
I have changed the petrol in both in case of contamination, checked the tank filters and drained and flushed through the float bowls.
One thing that did occur to me is they are both fitted with inline fuel filters which dont seem to completely fill with fuel.
Could the carbs be sucking air and fuel in?
Before I start to dismantle and rebuild carbs I thought I would check if anyone had any other ideas?

Many thanks
Colin

[Taffus]

pop the fuel cap when you are riding, if the problem goes away then the breather air hole is blocked

[colin.carter]

Thanks Taffus.
I have tried this already with no sucess.
Sorry forgot to mention it.

Cheers
Colin

[PAULJAC47]

If the tanks have a prime position try runninig on that,also has the fault occured since you fitted filters?if so thats probably the fault not emough flow if no prime on yout tap rig up temp feed from another source and see if prob clears in my experience vac taps are a pain Cheers Paul J..