MCN’s Yamaha TZR250 club racer
12 June 2009 10:47
In April I started my first season of club racing at the Bemsee Centenary meeting at Brands Hatch racing in the Norfolkline Yamaha Past Masters series.
It was the first time I’ve raced my own bike – the off-season has been spent prepping the bike and testing, but this weekend would show if the effort had paid off.
Fortunately it did – although I was a reserve rider for the over subscribed meeting (meaning I’d only get on the grid if someone else didn’t), I got out in three of the four races. On the first day I finished 18th and 11th out of 38 riders – finishes I was over the moon with, having started at the back of the grid! My Sunday race started from 11th on the grid, and I gained three places before slipping back to 9th on the final lap. I was grinning from ear to ear for the rest of the day.
Without the right bike I couldn’t have done it – my 1988 Yamaha TZR250 1KT has benefitted from an expert build and the right parts. Here’s what makes it fly:
ENGINE: Standard TZRs make 45bhp – mine is good for 10bhp more. This is down to a Graham File race tune. The cases, barrels and YPVS blades have revised porting which flows more fuel/air in and out of the cylinders. Jolly Moto expansion chambers allow the engine to rev higher than standard, and the carbs are re-jetted to suit (slightly rich to maintain reliability). The restrictive airbox nozzle is also removed. I use a 15-tooth front sprocket with either a 44, 45 or 46 tooth Renthal rear. Chain is heavy duty Tsubaki. Castrol A747 two-stroke oil is recommended, and Silkolene gearbox oil is changed every two meetings.
CHASSIS: The frame and swingarm has extraneous brackets removed and changes to allow seat unit fitment. The shock is standard (with new oil and seals), fork externals are standard with Maxton internals that give much better control than standard. Shorter suspension links have been fitted – mine are 4mm shorter, though I intend to try even shorter links to raise rear ride height further.
BRAKES: The standard front master cylinder is connected to an R6 caliper (permitted within the rules) by a HEL stainless steel brake line. SBS Dual Carbon pads (£44.99 per caliper) provide strong stopping power and good feel, but only when they’re warm. Rear caliper and master cylinder is standard.
WHEELS/TYRES: The standard front wheel runs a 110/70-17 Bridgestone BT-090 (excellent dry grip, good in the wet too), and a 3.5” rear rim from a TZR125R is a direct fit and required for the series control tyre – Dunlop GPR70s, available at a special rate to racers in the series.
OTHER DETAILS: ARD race bodywork – the standard TZR pattern fairing, TZ seat unit was already fitted, and has been sprayed in Rucky Strike colours (a pastiche of the Lucky Strike Yamaha 500GP team based on my nickname, Rucksack). A Venhill quick-action throttle gives a light, instantaneous action needed for fast corner exit, and a Skidmarx flip-up screen (with the touring lip cut off) gives me room to get tucked in. The rearsets are made to standard dimensions with solid footpegs – both kindly made by a friend in the workshop at RAF Wittering.
Bridgestone: See your local tyre dealer
Renthal/Tsubaki: 01522 791369
Graham File: 01303 262 222