zxr400l engine setup for racing

[mark400]

I have 2 questions on zxr 400 L engines :

I can't quite afford the stainless valves, what should I look at for the clearances for inlet and outlet for racing on standard valves & is there a difference between the L3 and L9 clearances & how do I tell which engine I have, is there a clue in the serial number stamped on the casings..

Also, there are two types of cam chain tensioner, is the later one better, and is it still better in an older engine ( i.e. will an L1 engine benefit from an L9 cam chain tensioner ?) & again, how do you tell which engine. Both my engines now have the later inlet rubbers for the ram airbox to fit correctly.

I'd really appreciate any help, especially as I have had 3 rebuilds due to dropped valves!

Incidentally, both my engines blew oil out of the oil seal behind the sprocket, has anyone else had this, and why does it happen?

It hurt when I fell off on my own oil!

There isn't a ridge in the casing to hold the oil seal in, it just pushes in and out. Could my problems be due to excessive crankcase pressure, my engines are mildly tunes with about 13.5 to 1 compression,standard bores, or do the seals always pop out if they are cold?

OOPS, that was 3 questions !

[mark400]

Sorry, I meant - Do they pop out if they are OLD !

[zxr67]

Hiya mate, had similar problems to you last year, I took my bike to Chris Neild at Dynopro-racing.co.uk hes pretty good with the kwakis and should be some help to you. I'll pm you Graham barrows number later.Ste

[cargo]

I've never known that output shaft seal to leak or pop out..................I would reuse them after rebuilds with no problems. I'm assuming you still have the breather in place ?

Are use using genuine Kawasaki seals ?

After 3 rebuilds for dropped valves I'd be looking at who did the rebuilds and asking a few questions.

I find the later model cam chain tensioner easier to use given Mr Kawasaki introduced it and stuck with it for years it must have been an improvment.
I do have the older one on one engine and have no problems with it..................they are I believe interchangable.
From experience cam chain tensioner problems I've come across arise from people not realising how they work and refitting them incorrectly

[rmkd177]

If you go into....'Having problems' section...valve clearances...ive posted on there about valve problems. Regards your final drive oil seal popping out? ive had this happen on a few occasions...only once on our own bike...its not good,not even once!
I now make a small plastic cover that is an extra precaution to hold the seal in. More often than not its happened on the later engines 97>. As for stainless valves...i dont use them...i think there are an expense that can be spared and if the standard (used) checked, and in good order they will last along time.

[mick41zxr]

Like Roger I have found no problems with the valves, nearly all of the time I have seen valves drop is due to re using the valve springs. There are two types (white -earlier models blue - later ones) with different spring seats, they also respond differently when analysing them on a rig with a strobe. Stating the obviouse here but most internals in a race engine are consumerables & must be changed regularly. Also the higher you rev the quicker they wear, I have limited my bike to 14,500rom & springs have lasted two seasons without a valve drop for the last 8 years replacing the valves twice in that time. If I was going to 16,000rpm I would probably change the springs every season. Seems expensive at the time but far cheaper than a blown engine.
Hope this helps.
Regards,
MB