ZXR 250 A not revving out ?

Have you got the correct jetting for that pipe youve got on?

 

Out of curisoity , can you post your engine number ( the first 8 digits) , Im curious if you have an A or C engine as we have had a few A model bikes with C model engines and they wont rev over 16k

 

definetly looks like a zxr engine, balius engine are blinged out more, i think kiffsta might be onto something, someone had the same problem on here.

 

The rocker cover Is the same as the balius if you look closely, but most likely Is zxr engine I was just throwing it out there. The engine numbers will be good to see.

 

Well that can't help, the inner 2 factory should be 128 and the outer 2 should be 125. Going back to a stock setting may help to rule that out.

 

Have to agree with Murdo, Fiddling with jets and air mixtures can only worsen the situation. What in fact is occurring is the overall balance is being upset ie: air / fuel mixture which in essence does not produce more power.
I think the Jap engineers at the time had done the hard work and gotten some great result power wise, that's why using the air box on the bike is vital in getting the correct continuity of air flow, couple this with the correct jetting should get you to a better place, only my 2 cents worth.
Good carburation is a fine balancing act, air to fuel ratio.

 

Definitely agree I always say to mates who lower cars and all that jazz is the r&d put into development is extensive and if not racing it y change it they spent $$$ and time getting it right!!! Return to stock and check mate

 

Min - two seemingly unrelated problems may be the same thing!
First, my fizzer (fzr250). Brought it with pod filters, with duct tape wrapped round them. This is not a joke. Ran okayish but not great. Took the tape off, it would hardly run at all. Went back to standard airbox - magic all cured.
Any deviation from standard on these tiddlers seems to ruin their running. I can't agree more with your decision and everyones advice to go back to standard.

However, cam timing that's a bit out can mess things up too, and whatever you've got going on with your chain and tensioner cannot be right.
Even if you chain is a bit long because it's worn, the chain should still be tensioned in order to stop it flailing out and hitting the cover. Unless your tensioner has used all it's travel then it needs to be tighter.
There's quite a lot of force trying to chuck the chain off the sprokets. Think about it, the chain's heavy and even at the half engine speed it rotates at, here up to 10,000 rpm, there's loads of centripedal force trying to pull it off. That's why spring loaded tensioners have a ratchet system, the spring alone is not enough when the revs get up.
Fizzers have a steel cover with a big nylon block inside it in the area between the cams to help as well.

Anyway, let's imagine that you've got your exhaust cam set up perfectly, and at standstill your inlet cam set up perfectly. When the motor gets some revs on the peice of chain between the two cam wheels is lifting and hitting the cam cover as you report. Even if the exhaust cam timing stays correct, the chain lifting off will advance the inlet cam, which is clearly not what you want. If it gets really extreme you may even get pistons hitting valves.

I'd sort this sharpish, you may find it improves your not revving out problem,...either that or compliment yourself on inventing a very simple vairable valve timing system!!!