Wont rev past 11500rpm

[boostin]

Hi guys,

Recently took my ZXR400 to the track and to cut a long story short it won't rev over 11500rpm. It gets there just fine, but then develops a miss that almost sounds like a rev limiter. It is the same in all gears, as soon as I shift up it is fine until it gets to 11500 again.

To add a little to the long story, a day earlier I had it at the track with a few problems that ended in me taking the batt out to be charged, and when I put it back in I had it round the wrong way and blew the main fuse. Could putting the battery terminals on the wrong way have damaged anything before the fuse blew. I heard the fuse blow straight away and thats when I realised that the terminals were backwards. It had not been running before the batt incident so I am not sure if this had caused it...

Any ideas of where to start looking? It had been sitting for about 6 months before going to the track with the off start up every couple of weeks.

I am thinking of starting with the plugs/leads first...would they cause this type of problem?

[RedexRobB]

Hopefully the fuse will have blown before it damages anything, thats its job. I suspect its could be gummed up jets from standing about for six months. You can chuck some redex in which might clear it out, if not then you might have to strip the carbs. since youll have most of that apart round there to check the pugs and leads its worth checking and its free!

[zimm]

battery backwards ? consistent "rev-limiter like" missfire ?

sounds like its blown the CDI.

[boostin]

Thanks for the replys guys.

I pulled out the coils and checked the resistance. The primary windings are within range, but the secondary ones are around 23k. (should be 12 - 18 going by the manual). I pulled a coil out of my ZXR250 and had the same reading, so I assume its not the coils.

I have pulled out the CDI to check the resistance over the pins, I seem to get reading all over the show, and not many of them are within the spec of the manual....Going off these readings would you recommend I try another CDI first? I may be able to get one to try. I would have thought that it would not run at all if the CDI was damaged, have they run up to a RPM then not gone any higher when damaged?

Thanks,

[zimm]

yeh, they have a "limp home" and a "speed restrict" mode aswell as some "i dont work anymore" settings ..

try a mates and see if it fixes it ..

ive got a cdi off an L4 import you can have for a tenner plus postage if its the problem

[boostin]

Thanks for the info Zimm.

I will do some testing and let you know how I go.

I am in NZ so if I can't find a local one, I might take you up on the offer.