Zxr Blow up, Help

[800rider]

Hi everyone was hoping someone can help me as am new to zxrs and racing .
On my first outing I managed to Grenade my motor and once I repair i want to make sure it does not happen again.
The bike is circuit only and has a pipe and carb tune plus running a 250 rev counter.
I think the problem was the lack of a relistic rev limit due to non standard rev counter , I was reving bike to 16000 in lower gears and holding 15500 in 5th and 14500 in 6th but at times coming out of corners the bike would rev higher and fall on its face ( I thought it was hitting rev limiter but I think it was valve bouncing and the fact that it has a reverse shifter probable didnt help)

Anyways eventually the motor snapped off a valve and went slow and noisy

Will fitting a standard Rev counter remedy problem ( and standard shifter)and 16000rpm to high to rev, eg what is standard rev limiter set at
Would Apreciate any help thanks

[Jeppo]

Reverse shift pattern shouldn't make any difference to engine performance, it was solely the lack of rev limiter, or perhaps dodgy valve clearances....
Standard I believe is 14500. And realisticly you wouldn't wanna take it any higher than 15000, theres just no need as peak power and torque has gone by then.
No need to get a different rev counter just get a limiter on it.

[tk400]

standard 14,500 - 14,800
SP 15,200
F3 Factory Kit 16,200 RPM

A standard engine will drop valves at 16,00 rpm or more

also if it is standard it would be slower if reved beyond 15,000 RPM

sounds like it through a collet and dropped a valve.

cheers

[will#224]

The rev counter has nothing to do with the rev limit, you shouldn't really need a rev counter, just change gear with engine noise and feel.

Sounds like engine has poo'd itself due to age rather than a specific rev amount or the way you've ridden it.

Most are 10 years old plus and all get a hard life. In my opinion if it isn't stripped every year and refreshed it will happen again.

[800rider]

Thanks for thoughts so far , unless the ZXR250 rev counter is reading inacurate the Engine easily pulling to 16000 before the power dropped off, it is a circuit only bike and im not sure of mods done to it but it made a fair bit of power for such a small engine,
Is some way off Id ing which CDI I have according to Rev counter I have F3 one??

[Ballsout Racing]

Absolutely no point in using 16,000rpm unless you've got a very highly tuned motor. Mine is and the power starts dropping off at below 15,000 , allbeit only slightly, although it will and does rev to 16,000; I have been told not to take it above 15,500 and 15,000 if I want to extend engine life

[800rider]

Rev Counter must be wrong then as I said before pulls easily and freely to 16000 and never hits any limiter , from what Ive read elseware valves are probable old and as the track back strait was Aprox Ikm, valves didnt like sustain rpm , still dont get why I never hit Rev limiter though

[Davw]

What is the serial number on the CDI?

[800rider]

CDI numbers are
21119-1299
131800-5480
12v TNF14 Y couldnt quite read the TNF14 so may not be fully correct and the Y is larger than the other letters
Denso Japan

Thanks for you guys help so far

[Davw]

CDI numbers are
21119-1299
131800-5480
12v TNF14 Y couldnt quite read the TNF14 so may not be fully correct and the Y is larger than the other letters
Denso Japan

Thats not a number that I recognise. 21119 is the generic number for all kawasaki CDI's and the next 4 numbers define the model. In general terms the zxr 400H cdi's end in 1271, 1272, 1273 and the Ls are 1331,1332. The Y is a new one. What colour is the sticker that this is on. There are (as far as I know) three colours - red=H model, blue=L model and yellow = import

Check this thread viewtopic.php?f=55&t=5228

for a listing of CDI's that various members have come across. Might be best to post a photo if you can

[800rider]

Maybe its a ZXR250 CDI

[tk400]

It could well be a 250 CDI. that would explain the lack of a rev limit as they are 19,000rpm limit or so. I have used one in a zxr400 and they are definately a straight swap. the advance curve wouldnt be that far off either. But sounds like a dangerous idea. The SP and F3 are a mitsubishi unit and much larger. cheers