Help ZXR250 1994, Will idle perfect, only revs to 12k then stops running

Can you pm me the engine number ?

 

It's on the underneath crankcase on the right hand side

 

There's one of two scenarios I think is playing out here.

Either your vacuum petcock has a problem (most likely with the diaphragm) or it is an electrical problem (stator/reg rec circuits).

In the case of the petcock, if you're pushing hard for a greater amount of fuel and it's not working properly it will be restricted until eventually the bowls run down to empty. Easy enough to check, get it going take it for a run and when it stops open a couple of bowl drain valves to see how much fuel comes out. If little or none I'd imagine you need to replace the petcock.

The other scenario is the electrics. Idle is a low current draw but when you're really pulling and the current isn't being supplied you're going to have spark problems (weak spark, inconsistent spark). This ones a bit more difficult to diagnose as it could be through the plugs, coils, reg/rec or stator... see if you can test all of those. The pickup you mentioned is part of the stator circuit and it's easy enough to test if you google how.

 

Theres the problem, i seen you posted the engine number on kiffstas profile and you have an A model engine in a C model not sure but the ignition timing is different as they are a completely different engine internally.

 

So running a C model CDI we assume? Which would have totally wrong ignition timing.

I was going to say that it might be something along the lines of a speedo-restricton, I know some Japanese bikes get ignition cut at 12k when there isn't a sensor from the speedo

 

I had a very similar problem with my ZXR after taking it to a mechanic the bike would not rev past 10,000rpm. It turned out that the four wires that connect to the coil packs where put on in the wrong order and that was stopping it rev. Once that was fix the bike was using the whole rev range once again. Just a thought

 

Check this ^^

 

While you are at it post us the cdi numbers and possibly a pic. If you are indeed running an a model engine with c model electrics and carbs it's never going to run right. Have you had your carbs apart? What were the jets?

 

Yes a ZXR250c engine number says zx250cXXXXXX so someone in the past has blown a motor and put in that one, most likely struggled to get it to run correctly and sold it. @kiffsta @Frankster any input guys?

 

http://2fiftycc.com/index.php?threads/my-zxr250a-project-log.1179/page-5#post-18063 have a read thru this one.
So you have a couple of problems a cdi meant to run the c model engine, and carbs meant to run a c model engine. The wiring is different for the cdi units as well. And the a model carb jetting is meant to be 125-128-128-125 and they don't run a vacuum valve.