the continuing saga of the stuttering sv....
 

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Does it operate nice and smoothly for as LONGas you're doing less than 30mph? i.e if you spend 5 minutes riding around under 30mph, is it running okay, everything nice and smooth?

If so, that would rule out faulty fuel tap isues, and fuel blockages. Ever tried redex in a tank of fuel? Can't say it would definetely sort it out but might help. Also, I can only presume the carbs are mounted onto the engine block correctly?

Is it under high revs?

Lack of petrol possibly.

The gremlins have certainly got into your bike!

This problem now sounds a lot like a fueling problem. There are lots of things that could effect your bikes metering of fuel. Check the simple stuff first. Make sure all the moving parts around your carbs throttle boddies are all linked up correctly and have free movement. Obvoisly if they are spring loaded it won't be free but you know what i mean, unobstructed, smooth movement. Also check that all the wee rubber pipes are not split and are properly fitted. Makesure your fuel lines not leaking and any fuel filters are clean. Check for kinks in the fuel line as this will restrict flow.

Not sure if you have carbs or Injection on your bike. Carbs have a diaghram that opperates the needles using vacuum. If the diaghram is split you would find the engine will idle and might even accelerate a little but it wont go fast, and will fail to go up hills etc. If its injection there may not be enought pressure in the fuel rail and you could have a faulty accumulator or fuel pump. Also with injection you could still have a faulty electrical connection which is making the ECU behave incorrectly. So check out those ECU wires, all the way to the sensors too. Kinks in wires can be just as bad as kinks in fuel lines, they indicate damaged wires, so look out for these too.

Sorry to hear your having such a hard time with you bike but keep at it, you'll find it in the end, there are only so many components in a bike.

Doesn't the fuel tank have a breather to allow for air to replace the petrol that is being used? It used to be a little pinhole in the cap on old bikes........If yours is blocked or the breather pipe kinked then after a couple of mins you'll have a vacuum in your tank and petrol being sucked out of your carbs/FI! Try running until the problem appears then stop sharpish and release the filler whilst listening for sucking sounds....just an idea