MZ Race Bikes

There are two basic types of people who choose the MZ class to go racing.

There are those (me included) who are simply after the cheapest way to racing, elbow to elbow, around the nation’s best circuits, and there are others who want to race too but love just as much to tinker, built and create their own machine.

Because the race version of a somewhat agricultural road bike tends to get shaken to pieces with the enormous stresses and strains of all-out racing, whichever category you fall in to, you will end up doing a fair amount of spannering.

So, right here, I will give you the best bit of advice you will ever hear. If MZ racing is for you – and you have tried one out with our great MZ Experience scheme – buy a ready prepared bike. Don’t try to build one from scratch. Not at first anyhow.

Even if you are an engineer with a fully kitted-out workshop, these modest bikes have developed such a long way from their racing beginnings that it would take you huge resources and time to emerge with a competitive bike. What’s the point of that when the whole ethos of the formula is that of a budget racer?

Far better to buy a proven machine – see our website’s For Sale section or just ask around the paddock.

Once you have your MZ racer, the first job is to make it fit you. Get comfortable by adjusting the clip-ons, levers, seat and footrests. You may even have to make up you own rearsets to get the perfect racing crouch. This is even more vital as fairings of any shape or form are banned (another cost-saver). The further you sit up, the slower you will be on the straights.

Having got a feel for the machine, you have a number of choices to make.

Tyres.

It is still possible to get out there and have some fun just using intermediates. One set of wheels and tyres for all weather conditions – but don’t expect to run with the leaders, especially in the wet.

You could learn the racing ropes with inters, before investing in slicks, cut slicks and wets. This means having three sets of wheels, along with tyre-warmers and a decent sized generator.

If you have listened to my advice and bought your MZ racer with a good spares package, you may already have these, at a fraction of what it would cost to source, build and convert your machine to accept – be they wire or cast wheels.

The one really good bit of news is that MZs run the same size slick (and wets) as the GP125 boys. This means that you can pick up second-hand tyres going for a song. And, as the MZ weighs next to nothing, tyre wear is minimal. It is this key point that makes MZ racing so much more affordable than just about any other bike formula. One set of slicks could last you half a season. Compare that to other bikes on the grid, which can get through a set of tyres every meeting!

Other more subtle choices are:

Frame.

ETZ frames are the choice of most – either long frame (for stability down the straight) or the short frame (for quicker cornering). The size of you will have some bearing on this.

Engine.

The MZ 250 ETZ has come a long way with modifications. Tuned barrel, extra boost ports, straight-entry inlet stub, cut-down head and fins, a forged piston, a Yamaha con-rod, aluminium clutch, modified primaries and specially-made 5th gear are just some of the requirements for a competitive powerplant. Save yourself some grief and select one of our engine tuners (again they can be found on our website) and let him do the business. Very often they are at every meeting and can help you solve most problems.

Carburettor

The standard BVF carb has to be used, although the float bowl drain has to be piped into a catchtank. To make this work you need breathers. The carb can also be bored out – to a maximum of 35mm. But before you get your drill out, the size of the bore will have to suit your engine tune.

Exhaust

There are whole bunch of rules to do with the exhaust. The reason – to keep tuning limits (and costs) in check. Again, within the rules, the exact shape of your exhaust will depend on your engine tune. The days of the drainpipe exhaust, with a seven-inch mid-section, have well and truly gone, and even now the tucked-under-the-swinging arm pipe is being replaced with an up-swept version, with the added benefit of better ground clearance.

Suspension.

The forks are worth spending some money on if you want some serious confidence going round corners. Although externally the forks have to remain the same as standard, inside a lot can be changed. Once it was enough to add a couple of two pence pieces over the top of the springs and just use a thicker oil. Now the whole internals can be changed. Top-of-the- range is a Maxton conversion, although a couple of MZ engine tuners offer a similar fork, but costing far less.

At the rear, the twin shocks can also be changed for expensive Maxton versions, but I found nothing wrong with cut-down standard MZ shocks. It’s all a question of your budget.

Brakes.

The front brake is the only one to worry about. I have never used a back brake on the race track – its only there for the scrutineers. If you have wire wheels, even the standard drum is fine.

The front is a different matter. It mainly depends if you have wire or cast wheels. This will determine what disc is available to you. I’ve always depended on a standard MZ disc and caliper, with a Honda master cylinder. It’s always been up to the job, provided I put enough pressure on the lever. If you want one-finger braking, I’ve seen six-pot calipers and floating discs fitted to some bikes. Your budget will decide.

Seat unit.

You can use any seat unit you like, provided it is mounted behind the tank and doesn’t hang down to cover the frame. As you are not allowed to weld anything to the frame, you will have to make up a sub-frame that can be secured by bolts or universal clips. Don’t, as one guy tried, think cable ties will do. One other tip, choose a robust seat that will withstand helpers holding on to it to give you that all-important bump-start.

PAYS YOUR MONEY AND TAKES YOUR CHANCE – that’s the whole ball-game!

by Simon Nix, MZ Racer (March 2011)

 

 

More about the bikes……

Petrol Cap
In-case you had not noticed, there is a breather hole in the MZ petrol cap, make sure this is not blocked (many racers have drilled a hole straight through) as this will stop your bike running. If you drill it fuel can spray out of the drilled hole when riding! Just make sure its not blocked. 

Rearsets and clipons
 Are essential! Walk around the MZ paddock to see the variety.

Petrol / Pre-Mix  
Not all circuits sell petrol on race days, so make sure you have enough with you. Super Unleaded petrol is best for MZ racing. You will need something to measure both your petrol and two stroke oil. A funnel is also very useful. Your tuner will advise on the mix. Make sure you have enough fuel! One MZ racer (trying to save weight) ran out of petrol after a race was restarted after one lap as he only had enough petrol to complete the original race distance!

Lock Wire
Used to stop key parts of your bike falling off during a race. See ACU regulations for things you must lock wire. One of the coolest tools you can buy when you go racing is a pair of lock wiring pliers, but lock wire can still be used without them. A good habit is to always lock wire key parts after “tinkering” with your bike. You are less likely to ride off with unfinished repairs if you have checked the lock wire before you go. Trust us, at 3am the night before a race, when you are half asleep, you always forget to tighten something!

Paddock Stands
It is handy to have something to keep your bike upright while you adjust the chain, pour in petrol, etc. You can use axle stands or a pile of old bricks but one day it will fall over, break something and cost you money and perhaps a race.

Fire Extinguisher
ACU rules state that you should carry a 2kg (min.) dry powder extinguisher – not on the bike, of course, but with your equipment in the paddock.

Where can I buy spares?
There are many sources of MZ spares; fellow riders,  ebay, bike breakers, MZ dealers. They are readily available and are fairly cheap.

Clean your bike!
If you clean your bike after you return home from a race you will achieve two things. The first is one less thing to do before you go racing again (scrutineers like clean bikes). The second is that you are more likely to notice if something has broken. When you find a nail in your tyre as you load the bike onto the trailer on the morning of a race, you know you are going to have a bad day.

Number Boards/ Race Numbers
MZs race with white numbers on green background boards for the sides and the front. You can buy your race numbers at the circuit.
Further details on MZ Tuning/Bike Building can be found in our Technical Information section along with a useful Gearing Calculator. Click here.