ZX2R mechanical issues (fuel/petcock??)

I recently bought a ZX2R-C from Sumoto (I know, have been thoroughly chastising myself ever since, feel free to add to the torment with tales of "I told you so") but would like to seek the wisdom from forum members over a petrol issue.

I've done some quick research and it appears that what I have is a petcock problem, but not sure exactly what this means, or how much it might cost. Basically my bike only runs in the Prime position, it conks out on "On" and "Res" positions after a couple of k's. Can any of you learned folk provide a little more information on this problem and what it may mean?

Thanks in advance!

Could be one of two problems.

1. Vacuum line disconnected, kinked or leaking. There are two lines that go the the petrol tap. One is vacuum, the other is for fuel. If the vacuum line is missing, kinked or otherwise obstructed, there will be no fuel flow.

2. Petrol tap diaphragm cactus. If this is the case, grab a second hand petrol tap from a wrecker - they should have heaps.

The first is more likely. Don't forget to check both ends of the vacuum line.

Yes to the above & Rusty you forgot something .....
SUMOTO

Bet you wont do that again

oh & welcome to the club Podman

Thought I'd be nice and not mention it, 'cos I knew everyone else would!

cant you take it back to the dodgy pricks?

cant you take it back to the dodgy pricks?

Would you want them working on it?

Unfortunately not, not in Melbourne, but the latter point is the valid one. After some earlier mechanical issues which caused much consternation and discussions with the kind folk, I've decided its not worth the hassle again.

But from the earlier post, it sounds as though it could be a simple fix, which is what I'm, hoping for. Other than that, the bike is reasonably good, just disappointing when you spend a wad of cash and its not everything you hoped for. Still looks excellent, and hopefully this will be the end to the problems.

Updates to follow.

So, turns out that the vacuum line is probably the wrong size for the bike, so that is one issue causing me grief.

The other problem is a "flat spot" between about 9,000 all the way to 14,000 RPM, which is either a carby balancing issue (best case scenario) or leaking valves or overhaul of valves issue (worst case scenario).

Can those of you more mechanically minded offer any advice/comment on what this may mean?

Apologies for my naivety and ignorance, thanks in advance.

Cheers,
Andrew

It's possible that the valve clearances need adjusting, but carbs are more likely. How many k's? If the valves were leaky I'd expect a drop in power and rough running.

It's also possible that the carbies are filthy inside. You may find that with a good clean out and balance everything works nicely. In simple terms, balancing the carbies is adjusting the throttle butterflies so that each cylinder is getting the same amount of fuel/air mixture. This spreads the power pulses evenly across all cylinders, resulting in smoother running and better power delivery.