Race Prep A TZR

The Team Stoater Guide to TZR race preparation

Written by Higgsy   
Tuesday, 09 December 2008

All opinions in this article are mine and mine alone. If you want to use or steal bits of it, feel free, but I'm not responsible if anything happens to hurt you or your machine as a result! Neither am I recommending one supplier over another it's just supposed to be an informative narrative. I am also indebted to the excellent article by Neil Ronketti which got me started in the first place.

So you want to race a Yamaha TZR250?

There are and have been quite a few championships that the TZR 250 2MA or 1KT can and would have been run in, for these purposes we will be preparing the bike to run in the BEMSEE/MRO Yamaha Past Masters Racing Club Championship.

Unfortunately the days when you could turn up on a lightly modified road bike with a standard engine and not be lapped have gone. This is generally considered to be the basic benchmark set up as used by most of the mid pack to front runners:

Standard frame with modified front forks, raised rear suspension, and race bodywork
Tuned engine with JollyMoto or similar expansion pipes putting out somewhere around 48hp and above on an accurate dyno
3.5 rear wheel to accommodate the control Dunlop GPR70 rear tyre.
Front brake can be a standard calliper and disk, Brembo type iron disk, EBC prolite, and Yamaha R6 ‘Blue Spot' Calliper in various combinations.
KR1S, RGV250, Honda MC18 or similar radiator

It is possible to go and race on a standardish bike, and some have done it with some success, but it can be a frustrating experience if your aims are to be mixing it with anybody not at the back of the field.

Find your TZR:

For this we mean the UK model TZR 250 2MA or the import 1KT, no other model is permitted.
This can be in two main ways, the first is to buy an already prepared race bike, and the second is to buy and modify a road bike.

Buying an already prepared race bike.

I speak from experience that a bike advertised as ready to race can be far from that! I have a sliding balance of cost verses what it has and needs doing. If you are lucky enough to be able to afford to buy a previous front running machine then the chances are that all the important stuff has been sorted already. There are quite a few older bikes that come up, normally on eBay, that will need updating to comply with the latest regulations and to be competitive, but they can be a good buy. For instance the bike we bought for Eddie to ride this year was last raced in 2005; to be competitive and to comply with the regs it will need the 3.5 rear wheel and possibly a set of pipes to replace the standards on it at the moment to up the power and save weight.
Find out as much about the bike as possible, providence: who raced it, there are fellas out there who would win on a moped if you put them out on it, has it had a recent engine rebuild, preferably by an established tuner, when was it last raced, what is the state of tune of the engine, what else has it had done to it, suspension, electrics and does it come with any spares because you will need them. Its all well and good buying the championship winning bike from 2001 but that was a while ago, so what's happened to it since?
This is where my sliding scale comes in, Eddies bike was £500, it came with a spare engine in bits, pretty much all of the important time consuming stuff, was already sorted out and was well known in YPM circles, the engine is an unknown quantity but it runs and sounds strong, if it needs to have a tune then it's not going to break the bank if that and a few other things are all that need doing. I comfortably predict that the bike will be competitively on the grid for less than £800. It's race ready as far as all the plastics, electrics and running gear are concerned and needs little work to prepare it. Prices vary a lot, I think we were lucky with a bike for a novice; one of the top running bikes would probably cost four times as much, a decent mid pack bike I would guess at the £1200 mark.

The advantages: You shouldn't have to spend money and time fitting race bodywork, the engine will probably have been tuned, the bike will be set up to race with suspension mods, the electrics will have already been streamlined and placed out of harms way, and hopefully the previous owner will be able to offer advice on gearing and jetting.

Buying a road bike and preparing it yourself

Buy a running bike as cheaply as possible; the important bits are the engine, frame, suspension and brakes. Having working electrics is an added bonus. Paying a lot of money for immaculate bodywork and originality is pointless, as you will end up in the gravel at some point and the resulting rattle can re-spray in Rossi colours will negate all that! Nice TZRs are starting to fetch good money these days and although they haven't reached the high state of the LC prices, they are creeping up. There is also the purist in me that hates the idea of an immaculate road bike being turned into a racer, far better to resurrect a heap to a better life (Rant over). But anyway if you want to do it yourself, this should help:

Chassis: Not much you can do really, no shortening of the sub frame is allowed, brackets can be added to mount bodywork, obviously the road stuff like mirrors, side stand etc. needs to go in the bin. Fashion changes and the once ‘must have' polished frame has now become satin black powder coat! You will need to add a shark's fin rear sprocket guard to the swingarm, either make your own from a suitable piece of alloy or Race Products and R&G make a suitable one for around twenty quid. Either pop rivet or tap the swingarm and bolt it on.

Front Forks: The standard forks are pogoish in their operation, a cheap solution is 15 weight oil and a 90-110 mm air gap, an improvement can be made with Hagon or similar progressive springs but you may have to increase the air gap back to the standard 120mm, or if you are feeling flush Steve Jordon or Maxton can rebuild your forks into something far superior. Preload settings are a matter of experiment but on the Maxton forks I run they have been on Min all season, with the standard set up on Eddies bike mid way seems about right. I haven't bothered changing it from track to track as it doesn't seem to make a lot of difference with my 12 stone.

Rear shock: Not much you can do here as the regs forbid anything other than the standard shock to keep costs down. Provision is made for re-gassing, the tell tale sign being a bolt in the top of the shock body and spring changes to suit body weight. New shocks are still available from Yamaha, the later fork and tie bar setup being considerably cheaper than the earlier eye and cast linkage type. A lack of rear damping is a TZR trait unfortunately.

Raising the rear end: Helps the already minimal ground clearance, and quickens the steering by tipping the bike forward. With the later tie bar swing arm you will need shorter tie bars to achieve this, I'm reliably informed that 90mm is as short as you can go without things starting to hit each other. Not quite so easy with the earlier swing arm but its possible: On the inside of the swing arm, above the shock arm mounting point there are another set of holes. File down the boss around them until they are flush with the swing arm. Cut down a gudgeon pin to the width of the arm and the mounting bolt will fit through nicely. To be honest I'm unsure how much this raises the rear end because I couldn't be bothered to measure it, but it works just fine! The swing arms are not interchangeable as the shock mounting is different.

Brakes: Rear has to remain standard, but as most don't use it anyway it's hardly relevant. I use the cheapest pads from Wemoto on the grounds that I like to settle the bike with the rear into corners but I don't want it locking the rear wheel up as I'm doing it! It has to work to pass scruitineering.

Front: The standard calliper is very good and many use it, it offers good feel and with braded lines, EBC, SBS or similar pads and perhaps an EBC disc it's very effective. The Yamaha ‘blue spot' calliper is permitted and with Ferodo pads is a formidable stopper, it does lack feel though, and being rather rock hard in its application, reducing the fluid level in the master cylinder seems to help a little. The master cylinder itself has to remain standard fitment. If you have one with Japanese writing on don't panic, it's just from an import 1KT model and is permissible.
Braided hoses on both are a good idea although a standard with the blue spot is supposed to give more feel. Seems a bit pointless to me though.

Bodywork: Fairings must remain as the original silhouette; seat units are open (within reason)

Fairings:
Standard: Crashes well, seems almost indestructible (believe me I've tried!), but is heavy, the faring ears are optional and the standard ones break easily, Skidmarks make fibreglass replacements and although don't fit particularly well, I haven't managed to destroy them as yet. If you run a larger rad or different pipes then you may have to space the bottom out a little and do away with the v-piece. To get the Martin77 pipes I run on to fit, I had to cut rather natty TZ500esque holes in the sides. You will need to fill the headlight aperture with something suitable, lightweight fibreglass matting or plastic most probably.

Race: ARD in Newcastle, who support the class, do a nice and light replacement at a very good price and Race Products used to produce a slightly more road based item that pops up second hand occasionally. They are not as strong and don't crash as well but are easily repaired. The fixings can remain standard, but as you are gaining a weight saving it's probably best to do away with the ton of standard bracket and make something nice out of alloy to maximise this. The race fairings come with the Dzus fixings already attached.
I made the side fairing fixings by drilling and tapping some alloy rod from B&Q to take an M8 bolt either end.

Seats: Various years of TZ250 are the norm, but Aprilia RS250 and Honda race seats have been used to nice effect as well. Make sure you are comfortable on the bike and that you can remove the seat with the minimum of fuss. The standard rear bracket can be utilised with some modification, but there are a variety or weird and wonderful solutions to seat fixing including lumps of wood at strategic points. As long as it holds it on don't worry too much about engineering aesthetics!

Tank: Junk the fuel tap and run a line with a coupler from the reserve pipe underneath the tank. You can run two separate lines if you cut the filter out of the tank itself, which is what I do. The fuel cap used to have to be standard but the rules changed recently and you can now use any suitable cap. Most standard caps have the screwdriver key modification and caps off other Yamaha models fit, Eddies is of a Diversion 900 and cost a tenner.

Bar position: Standard placement, below the yoke or you can invert the top yoke to get something in between. I like the front as low as possible but it's a matter of taste and body size, experiment until you feel comfortable. I use the standard clip-on's as they are cheap and strong, I don't see the point of spending £100 odd quid on fancy replacements unnecessarily.

Footpegs: The ACU state they must be solid, but the standard ones shortened in half are fine, just make sure the ends are rounded off a little with no sharp edges. You can substitute nice aluminium ones quite easily or go the whole hog and fit replacement rear sets. The gear lever can be standard change, which normally is a bit sloppy at best, or modified to give a race change which involves a little spacing out of the footrest hangers. Probably the best option is to substitute the whole thing for a suitably bent lever straight off the splines and poking backwards. Honda CG125 is good apparently. Chop the rear brake pedal down while you are at it as it only gets in the way.

Lock stops: Either drill and tap the bottom yoke ears to take a bolt or nut and bolt, or drill just in front of the ears and bolt through the yoke itself, I prefer the latter as I think it's stronger and the ears are less likely to break off in a crash. If you are going to make a lighter fairing stay then the lock stops can be incorporated into this to save drilling the yoke, a bar across the stay reducing the fork leg travel is the norm. Whatever solution you use, make sure that all the controls and cables are clear of the bodywork and that hands, fingers or even arms are not able to be trapped. Using the steering damper as a lock stop is not permitted!

Steering Dampers: A matter of choice and debate. I like one, many don't. Short ‘Kawasaki' type dampers mount to a bracket on the top of the frame rail, connected to the front tank mounting and to the fork leg. But there are many other solutions, have a walk round the paddock and see if you want to use something longer and fancier. I use a Rentec Ebay bargain that's probably as old as the bike. Eddies is similar and pink. (!)

Engine: If it hasn't had a recent rebuild by somebody who knows what their doing, then it's probably going to need one. At least have a look inside. Pistons have a nasty habit of working the rings loose then jamming them in the ports. Aim to change them at least mid season.

Tuners/rebuilders: Everybody has their favourites and I'm not going to start an argument here! A look at the top ten will give as many different tuners. Read through the Stoater site and you will find who I use, and there are some suggestions on the links page, all are more than capable of tuning and fettling your engine and there are probably more that I've forgotten, perhaps pick the nearest or follow a recommendation and build a relationship with them, at some point during the season you will probably get to know them very well! Don't be frightened to have a go yourself if you have the appropriate skills, there are folks within the paddock who have done so with great results. Whatever you do, spending time on a dyno to set the bike up will get the best out of your engine.

Plugs: It used to be the norm to run B10 plugs but most seem to run 9's these days, I actually run B95EG's to err on the side of safety. NGK rule here, not only do they sponsor the series but they work, unlike anything else!

Pre-mix: Junk the standard injector system and blank off the holes in the carb rubbers, if you want to remove the pump altogether than you will need to make or buy a blanking plate for the resulting hole.

30-1 is the norm, I use Castrol XR77 which seems really good with no apparent wear, but A747 as recommended by a couple of tuners, Silkolene PRO2 or any other top racing quality synthetic will be more than adequate

Jetting: Trumpet or no trumpet? that is the question! With the standard set up, dry filter and air intake trumpet then 230 mains is a good start, take the trumpet out and you will want to go up to around 320's on the mains. Either way 27.5 pilots are a good idea to stop the engine seizing on a closed throttle and to allow for the premix. The pilot jets themselves are notorious for clogging up, normal signs are a reluctance to take part throttle and a lag when trying to get on the power. Go up one notch on the needles and see how the bike feels, TZR's are sensitive to carb adjustments so make sure you do one change at a time, if in doubt get a dyno run with an exhaust analyser to see where you are. Much cheaper than an engine rebuild! To run with out the airbox will involve F3 carb modifications, which are illegal in the series, so leave it on.

Radiators: The standard rad is just about capable of cooling the bike when tuned A better solution is to use the rad of a KR1S, RGV250 or Honda MC18, better cooling by having a bigger area, all are a bit of a squeeze and involve bracket making but worth it when the weather gets hot. With the standard rad I leave the thermostat in until the weather gets hotter. My bike will have the MC18 rad grafted on at some point. It's probably also worth getting a mechanical water temp gauge plumed into the system where the water is hottest as the standard electric one is a bit pants at the best of times. Run the overflow into a suitable container as a catch tank. Water only by the way, no anti-freeze allowed. Tip the bike over on it's side after filling to help displace any air caught in the system.

Electrics: Everything that doesn't make it go, control the powervalves and make the instruments work can go in the bin. You can run total loss, in which case the battery will need checking regularly but you can loose the charging coils off the magneto to minimise engine drag. Leaving the charging system on does mean that the battery is having 13odd volts passed through it, which could improve the spark a little. The battery itself can be junked and a battery replacement capacitor substituted to save weight. Me? I just run the battery and a charging system (when it wants to).

Keep the tacho and temp gauge or substitute as above, either make up a natty aluminium cockpit or cut the standard mounting down. Loose the ignition key and run the powervalves and ignition off separate switches. I use a toggle switch by the speedo for the powervalves and a RC30 type switch on the bars for ignition. Remember the standard switches are now over twenty five years old.

CDi and powervalve controllers need to be moved out of harms way, my bike has everything up front under the tank, but under the seat is more normal. I actually cut the wiring plugs off both bikes and soldered the wires together covering with shrink wrap, I've had a couple of dodgy connections with plugs which can be difficult to diagnose. Earth everything, twice! TZR's are fussy about earths and the standard one earth system is not enough in my opinion.

Exhausts: The standard pipes give good power but are heavy and restrict revving to under 10,000, chopping the end baffle down to the cap is supposed to add a horsepower or two at the top end. Some tuners cut open the pipes and remove the internal baffles which is supposed to boost power more.

Expansion pipes: Most run Jolly Motos or Gibson pipes which give a boost in top end power by allowing the bikes to rev higher, Jolly Motos are sometimes available from YPM members or Stan Stephens, the Gibsons from Gibson themselves.

Others: I run pipes by Martin77  designed for a TDR, still in development but they work well along similar lines to the standards but weigh far less. Swarbricks used to be the norm a few years ago but they make the bike rev far higher than I would want to go and the resulting midrange hole is difficult to ride round. Nikkons: A couple of people have used them, but ground clearance seems to be an issue as they are quite fat, unavailable new now but they do turn up second hand. I actually use Nikkon end cans which are truly beautiful!

Gearing: I ran 14/42 for most of the season, 14/41 at Snetterton and I will probably run 14/43 at Lydden. Another topic for an argument, but unless you are a front runner I'm not convinced messing around with it makes an awful lot of difference. 14/41 is Standard gearing by the way. Some run a 15 front sprocket with the appropriate rear to equalise the gearing, 520 race chain from the likes of Izumi etc. is the way to go, and with that gearing selection you can hard link it and not loose the spring clip. If you want to run a clip then lockwire it round the middle.

Wheels and tyres:
Rear: Dunlop GPr70, available through the YPM club to fit on a 3.5 rim from a later TZR2502xt, FZR250, TZR125RR. Nothing else.
Front: Standard 2.15 rim with a Road Legal tyre of your choice. Bridgestone 090 in 110/70 is the choice of most of the field, but Dunlop qualifier and Alpha 10 have been used by some.

Lockwiring: Drill and lockwire both sump plugs and the gearbox filler cap. This is mandatory. I also run a length of wire to catch the radiator cap if it falls off. It's a good idea to drill and lockwire the front calliper bolts as well!

Spares: Yes you will need them! Stickyouty bits fair worse in a crash, so complete footrests, levers and possibly bars are a good idea. Fairings can normally be bodged to get the bike out again, but a large selection of cable ties, a fibreglass repair kit, pop riveter and suitable alloy sheet are probably a good idea. Cdi and powervalve controller, stator and flywheel, servo motor and if possible a spare engine! We also take a spare rad, front brake setup, clutch cover, forks and petrol tank (God knows why but I'm frightened to leave it behind now just in case). If you've got it , take it, the day you leave it behind is the day you will need it!

The YPM class is superb in respects of how much help and advice competitors give each other, if in doubt ask a few people your questions. I've seen Pat Herron weld a set of pipes up in a tent in France and a queue ten deep at Snetterton waiting for Gaz Buttons skill with a blow lamp!

Whatever you do go out, have fun and bring beer!