Time Warp Formula 500
Not so long ago I was pleased to acquire a very interesting F500 with documented Isle of Man race history in a nicely patinated, un-restored condition. It was original down to the Douglas guest house sticker still displayed in the windscreen and the ancient ‘Wirral 100’ racing club sticker on the fairing Chassis number 2941 had been built by Moto Laverda early in 1980 as one of the last batch of Formula 500s produced and shipped to the UK as part of a small consignment of Formula 500s delivered to Slater Bros.
Chassis number 2941 in its current unrestored condition
When I bought the bike it came with a fascinating history file hand written by Mike Griffiths , a local racer who had bought the bike in November 1981 from Slaters with the intention of entering it in the following year’s Newcomers Manx GP. Prior to Mike’s ownership the bike appears to be one of the historic 1980 team bikes which took part in the 1980 F2 TT mentioned elsewhere in this section. Various special features on the bike suggest it was bike No.26 ridden by Lennart Backstrom of behalf of Cropredy Bridge Laverda dealers.
Mike Griffith’s meticulous hand written log.
Here are some interesting highlights from Mike’s painstakingly detailed log.
Bought from Slater Bros Nov 1981 for £2200 [list price £2600]
Also received spare fairing -which doesn’t fit- [top and lower] and tail unit [Montjuic]
Spondon Manx yokes to follow [recd] and spare petrol tank[recd]
Registered and taxed Dec 1981 but only did about 590 miles due to salty roads. Revs limited to 5,000 with one or two quick bursts to 6,000 in the gears
Jan 1982
Mike flying down Bray carrying the number 1 plate on his way to 8th place in the newcomers. Note the back wheel in the air.
Engine removed and top end stripped down
1]Pistons tight in bores. Some scoring had already occurred. Bores honed out by 3 thou
2] Valve seats very badly cut. Valves ground in and clearances adjusted
3] Balance shaft removed
4] Clutch dismantled and steel plates found to be a bit rusty. Cleaned up and reassembled. This should cure dragging clutch [it didn’t Aug’84]
Dismantled and checked swinging arm-don’t like look of design at all. Wear is likely to be rapid [it hasn’t been Aug’84]
First test session at Oulton Park, end of February [‘81] Runs great and seems plenty of power. Did about 100 miles, revs brought up to 8,000 towards the end of session. Almost keeping up with Chris on GSX1100. [short circuit] Motor a bit noisy; could be piston slap. Have bores been honed too much? [Yes]
*All advice points to regular re-torquing of head bolts*
First races at Cadwell, end of March [81]Ran well but severe starting problems. Have gone up 5 on pilot jet, but only slight improvement. Will only start reliably with choke on and the choke is hard to get at.
2 thirds on first day [non competitive field] About 9 th/10 th on second day [Good entry]
Mid April checked valves, torque head bolts [needed it] and re set cam timing which appeared to be a bit off. Seems to run a bit better now.
Race starting problems solved by addition of handlebar mounted choke lever. Will still only start reliably with choke on,but at least it’s handy now. Clutch drag still causing some problems, but gradually lessening with use.
Following a minor oil leak on generator side of the motor, decided to get rid of generator etc. And run total loss. New o/seal fitted. KR 124 tyres fitted [3.50 front 3.75 rear]
May Tandragee 100 5 th in class B 500cc It’s a flyer.
Sunday July 11 th at 3 Sisters - First win No more races planned until the Manx
Spondon yokes supplied by Slater’s for the Manx, won’t fit. Have to get them modified
Prep for Manx1] Fit new Nylocs all round
2] Replace balancer shaft
3] Check and adjust valve clearances and re-torque head bolts
4]Modify and fit Spondon yokes
5] Fit reinforcement plates at fairing mounting points
* Spondon yokes- new centre spindle fitted and yokes assembled on bike-big improvement in high speed stability
*Balancer replaced, using bearings with machined bronze cages. Vibration much reduced at high revs
Valve clearances Ex 29 27 25 26
In 20 21 23 23
Tandragee 100 petrol useage Tank contents 14ltr, 9 laps=47.7 miles, used 4ltr 11.9 miles per ltr
Manx GP 1982Tyre pressure Rear 32psi Front 30psi
Monday Morning very wet misty
Lap 1 36min 54sec
Lap 2 34min 52sec used 8ltr petrol
Monday Afternoon –clear, dry, very windy
Lap 1 30min 34.4sec
Lap2 30min 15.4 sec used 8.25 ltr of petrol
Thursday afternoon dry sunny, little wind
Lap 1 27min 56.8sec
Lap 2 27min 25.0sec used 8 .5ltr petrol *fitted new tyre, 38 tooth rear sprocket
Friday afternoon –thick mist from Hailwood’s Rise to Keppel Gate
Lap 1 37min 14sec
Lap 2 36min 53sec
Fueling
At start 14ltr in tank. After 2 laps [using 10 ltr] 4 ltr in tank. Tank needs to be filled at pitstop. Actually put 20ltr in quick filler
Max speed Ratios Prim. 2.65 G/box 0.813 Final 2.533, Overall 5.46
Max speed at 9,000 revs= 135mph
The Race
Roads damp in places, high winds on second 2 laps. Pit stop as arranged after 2 laps
Finished 8 th out of 21 finishers
Race average 86mph
Fastest lap 89mph
Over winter engine stripped
*pistons rather slack in bores but should be OK for another season
*Valves replaced a ground into seats
*Loctited all engine bearings as some had been turning in their housings
* Balancer bearings had been very slack. Decided to try it without
Manx GP 1983
Year two and now in the Senior. Mike seems to have the alternator blanked off , presumably to run total loss ignition.
Tuesday PM Fine dry and sunny
Lap 1 27m 35.0sec
Lap 2 26m 54.4
Lap 3 Stopped at The Mitre and got drunk
2 nd Lap Top of the Mountain Mile it ran out of steam. Eased it off and power came back. Continued for 3 rd lap and lost all power just before The Highlander. Had a look and restarted . Ran OK until end of Cronk –y-Voddy where it went off again and gave up at The Mitre
1 free pint, bought a pint with “lucky” pound note, scouser bought me another and then the lads arrived. Landlady gave me a new “lucky” pound note.
Friday Race started at 2.30pm Weather dry , sunny and a bit chilly
Finished 6 laps in 45 th place. Great race.
Didn’t get on a ferry until midnight-long wait!
Oulton Park 8 th October 1983
500cc 4 stroke 4 th place won a trophy! [raining]
Manx GP 1984
Deja vu? Same spot on Bray as in ’82 , different dampers but with the back wheel in the air again!
Monday afternoon dry , sunny 1.5 lap dice with Kawa GPZ750
Lap 1 27 10.2
Lap 2 26 06.4
Checked top end, found pin in cam link had broken. Replaced. Put some Araldite on pin to stop it chattering. Phoned Slater Bros for a couple of new links. Lucky I decided to check top end instead of doing Tuesday morning practice
Friday PM 3 laps Found big end failed. Stripped motor
Saturday
Will Hodge organised new crank from Motodd @ good price [£245] Collected by Manx Parcels Monday, picked up at airport by me Tuesday 12.30pm Reassembled back running bu 8.30pm Sounds good Back to Duckhams 20/50
Spondon reduced offset ‘Manx’ yokes. Increased trail provides improved high speed stability. Note Veglia tacho and OE ignition key.
Mike’s log has provided as unique insight into the reality of running a Formula 500 in racing conditions in the 80s. The bike was retired from racing in the mid eighties and has been carefully stored ever since. The subsequent owner resisted the temptation to restore and simply used it occasionally keeping it in perfect running order . The bike feels taut and ‘sorted’ and has a very strong willing motor. Considering its Isle of Man history, a course which is known to be very punishing on bikes, the bike is in remarkable condition for its age. My intention is to keep it in un-restored condition to preserve its originality.
