www.zxrworld.co.uk

Hello everyone,

I've had a ZXR400 (L5) for a few days now and I want to convert it for the race track. I'm trying to read a lot from the forum posts, but many links are no longer available or the manufacturer is no longer on the market.

Basically, I'm interested in what "must have" modifications are for the ZXR400.

The following questions have occurred to me:
- Is there a sensible tuning for the standard airbox? e.g. removing the snorkel and using richer jets?
- Is the RamAir Box only available from bbplastics and is it any good?
- Are there any jet suggestions for the standard and RamAir Box? (I want to track the AFR value with a data logger at the next events)
- What can be removed and is not needed? (The oil cooler and the carburetor heater come to mind, for example)
- What other tips do you have?

Plans for the future may also include an electric water pump and the elimination of the alternator.

I'm doing a H model track bike with the following mods

- I ditched the oil cooler and blanked off the holes
- running a 1998 zx6r radiator
- used stock battery tray but made up a tray for the reg/rec and ditched the
number plate holder
- I'm not that fast so running a stock airbox and jetting
- Dismantled brakes and new seals/rehoned and installed braided lines.
- Getting the rear shock rebuilt (shaft was knackered and getting a new one made)
- Front forks got a complete refresh
- new radiator hoses
- took the top end off and removed a lot of crud from the coolant passages and put a new
head gasket on (supposedly H models aren't great on head gaskets)
- cbr600 coil mod

have you checked out the race manual on the main site?

Ditch the reg/rec and the stator off the crank and run total loss

Less weight on the bike in total and frees up the crank a little hp maybe from having no charging system

Take the oil cooler off an blank it

Remove the speedo

Fit better brakes and front fork cartridges potentially or change the front forks entirely

Better master cylinder for the front brake

Quick action throttle can be nice but not necessary

Remove the choke lever and all that housing from the bars and just use a little pull cord that comes out beneath the tank to pull the choke

Better rear suspension

Racing rear sets can go with SES as a brand

B&b plastics was sold off to new owners and I’m sure airboxs come up on the used market check out the 400 groups on Facebook big community there

Potential change the cool packs for sticks to make room in the airbox system

As someone said before radiator can be. CHanged out or at least moved to accommodate the ram air

Ignitech electronic ecu IP4 with push/pull quickshifter

Ported and polished heads if you can but not essential

Kent cams if you can get them but not essential

Omega over-sized pistons if you can afford to fit and rebore the cylinders to +1mm oversize

Flat face valves

Once you build your bike then get the jets added and setup on the dyno by dynotech for best applications

Building a race engine can be costly or not

Depends how much you want to spend

You can race in two potential category’s

Sub64 (standard) or full power ( 70/80bhp)