Pete Sutton tests the 750cc MV Agusta sidecar outfit

Mark Kay in the Isle Of Man

Painting of Dave Kay and Richard Battison during their 1st MV win in1986

 

 

Mark Kay and Richard Battison racing at the Isle of Man

The author and Richard Battison on the test run

The 750 cc MV Agusta Sidecar Racer Test

 

(An article by Pete Sutton for Classic Bike 1988)

 

'Let's face it, this outfit has been doomed since day one!' Dave Kay talks bluntly when he describes the tortuous and continuing struggle to get his 750cc MV Agusta kneeler accepted as eligible for CRMC three-wheeler racing. He thought the issue had been settled at the beginning of 1987. That season, his 20year old son, Mark and passengr Richard Battison, 22, rode the gleaming red 'fire engine' to some good results in close scraps with the all-conquering Hillman Imp-engineered outfits. But no, the controversy rumbles on.

'So far,' says an exasperated Kay, 'the ACU noise meter man has built the exhaust system and the Classic Club have designed the chassis. They seem to re-write the rules all the time, though, and want new things changed. We're fed up!' He concedes that some of the dictates are reasonable - the outfit's original sheet-style fabricated swinging arm was arguably later-looking than the Club's 1972 cut-off year, and was replaced. But he feels that the other demands have bordered on the farcical

 

 

Pete Sutton tests the 750cc MV Agusta sidecar outfit

 
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For example, most CRMC kneelers have heavily gussetted steering heads - a place of maximum stress on an outfit. But on the Kay MV, presumably because of the swinging arm, this was classed as 'fabrication' and disallowed. Thus the very short steering head is supported only by four butt-brazed tubes. This is inherently weak, but especially so now that the original frame toptubes that passed around the engine have also been ruled out, and replaced by a spindly bolted-up arrangement. Yet most other CRMC outfits have a gussetted head.

Built by 'modern' constructor John Derbyshire, the frame bestows a peculiar driving position. The kneeler trays are set wide apart (originally to straddle a rear chain alignment countershaft, also now banned as out of period), and the steering head and handlebars are quite high. So you perch like a begging dog behind the engine, resting your elbows on the strategically placed glass-fibre covers at each end of the camboxes.

It's a long wheelbase chassis, neatly constructed from T45 tubing, and it uses many small bracing tubes, instead of gussets, to avoid rows. The conventional leading-link front forks carry two Koni suspension units, and the rear swinging arm is now a tubular cantilever structure compressing a Mini rubber 'doughnut' and damped by one small hydraulic unit. This is a typical early seventies' setup intended the keep the overall height low. The sidecar platform is raised at the rear, and a secondary fuel tank is suspended beneath it; the primary tank is combined with the curvaceous wheel arch.


 

The rear wheel tracks about an inch inboard of the front one to line the chain up now that the countershaft is banned. This causes, says Mark, 'some instability on left-handers'. Twin 9inch discs brake the outfit at the front, one operated by the handlebar lever and the other, along with the rear and sidecar discs, is controlled by the foot pedal. Tyres are the ubiquitous Dulop 5in x L10 'greenspots' in a softish compound, on 10in Windle wheels.

'To be honest, you're mostly buying an engine when you buy an MV,' Dave Kay states - and certainly his unit is an impressive lump. Built from spare parts, it's a replica of a 1972 750cc Sport road-bike engine that itself is modelled closely on the four-cylinder racers. Kay claims that it's still in a fairly soft state of tune, and is reluctant to push the power up until he knows whether the MV will find a permanent home in CRMC meetings.

All we've done to this engine is increase the compression, port it a bit, install two high-lift cams we got from Arturo Magni, and make the four-into-one exhaust sytem from pipe 1/4 inch larger that usual,' he says. But with rebuilds of 26 MV engines under his belt, he has obtained a healthy 90bhp at the crank.

The twin overhead camshafts are adjusted by verniers and driven by a train of gears in a central gallery. The gears themselves are adjusted to a backlash of only one thou. Valve to valve clearance in the heads is a mere 40 thou, but the control exerted by overhead camshafts ensures that they never tangle.

 


David and Mark Kay helped to keep the dream alive in the motorcycle field by repairing and racing MV motorcycles

Sidecar test

Carburation is by four rubber-mounted 30mm Dell 'Ortos

 

High compression pistons are still available from the factory, and heads have been skimmed to raise compression still higher , while reducing squish-band clearance to almost nil.

Peened and heat treated steel conrods run on caged-rolled big-ends on the pressed-up crankshaft that turns on six split main bearings : the outer pair are ball types and the rest are uncaged rollers. These are clamped to a crank hanger that is mounted by 12 studs to the mouth of the crankcase and gearbox, a massive one-piece sand-casting.

Sparks for the NGK plugs are provided by one coil and a big gear-driven Marelli distributor; the battery sits in its traditional position in the sidecar nosecone. Two large helical gears drive the seven-plate wet clutch, and the gearbox has a standard five-speed cluster Kay would convert the helical primary gears to straight-cut spur gears and fit electronic ignition if he could be sure of eligibility.

The final part of the drive train is a current bone of contention. The road bike is fitted with shaft drive, but because it's a fragile unit with power loss and gearing problems, the Kay machine has a Magni chain conversion. It bolts to the gearbox where bevels used to turn the drive through 90 degrees.

This, it's been suggested, is post-72, but Kay disagrees. He has pictures of an F750 MV solo at Imola in 72 with chain drive, and claims that Magni, the ex-MV race shop boss whom he knows well, took castings from the original mould for his own conversion, which was used prior to 1973.

These complicated issues were far from my mind as the MV fired up with a lovely howl, the white needle on the handsome black Veglia tacho swinging smoothly. Richard Battison and I pulled onto a wet Mallory track, the four Dell'Ortos giving instant response with their light spindle-and-crank action. Strong, smooth torque is available from 3500rpm to the redline of 9500, although Dave admits he saw 12,000 once in the heat of battle.

The exhaust note is exciting but muted - on open pipes it was deafening, so the ACU demanded the decibels be reduced.

 

Pete Sutton rides the 750cc MV Agusta sidecar with Richard Battison

 
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Kay was initially upset, but grateful when he found that a four-into-one silenced system actually gives better power and crisper delivery. Changing up easily through the evenly spaced gears - the clutch is instant, light and positive - we circulated cautiously on the slippery track for a few laps. Richard moved surely around this large machine, putting his weight forward on the long, long righthander of Gerards to help keep the front wheel steering.But at moderate speeds the outfit is totally civilised. All the controls are perfectly adjusted and the strange driving position means you can lean forward onto the engine cover, lock your arms onto the camboxes and lever gently on the steering from the elbow down - no body-wrenching is necessary on this bike. The steering geometry itself seems perfect - light and sure, it guides the machine precisely round bends with the merest of pressure on the bars, almost like a modern outfit.

 

There is no kicking back, and the suspension copes well with Mallory's bumps. Back in the paddock we waited for the track to dry. The Kays always seem to have a crowd of MV enthusiasts to help, and they checked the oil (Mobil Rally One synthetic), tightened the unions to the large oil cooler and inspected the rear chain run, which seems about a mile long (although there is no problem as the rear whell moves so little)

At last the track was almost dry, so we set off to put in some faster laps. At higher speeds, everything becomes more urgent, but it's still a polite machine that does what you want. Round Gerard's in fourth with the engine shreiking at 8000 and the whole plot bucking and skipping on the bumps, it stays glued to the line with very little sliding or understeer. I must admit to having a few thoughts about that un-reinforced steering head though - we were going pretty fast!

 

 

Pete Sutton rides the 750cc MV Agusta sidecar with Richard Battison

Rocketing down the back straight, the MV screams to 8500. There's no need to make it higher, and the change into top is instant and close. I duck behind the flyscreen out of the wind roar and glance down at Richard who's lying flat and waiting to jump up for the Esses at the end of the straight. Hard on the brake pedal briefly , knock it down to third - have to be careful blipping the throttle, for the revs can scream up very easily - and we sail through the Esses with the trace of a slide. This is not a machine that drifts wildly at high speeds - tyre/chassis technology is in control.

At the hairpin, the brakes have ample power to pin it down, and we take the corner in a second gear slide - first is too low. You have to be gentle with the throttle, though - I banged it open too heavily once ,, and even in second the torque was enough to send us towards the chicane sideways on the verge of a spin.

Through the chicane, it did feel like a little cumbersome. the engine mass is quite high and, combined with Richard's light weight and the inboard position of the rear wheel, the sidecar wheel was easily lofted skywayrds when it caught the ripple-strip on the left-hand exit. This is quickly controllable - it went up and down slowly like a pendulum - and then we were back on three wheels and drifting in exciting little twitches as I screwed on the power and changed up round the downhill left-hander at Devils Elbow.

It did indicate though that the MV might be a bit of a handful at difficult left corners like Cadwell's Mansfield or Cascades at Oulton Park. Not that it bothers Mark and Richard - their spectacular all-out style seems to ignore such handicaps.

On a dampish track I erred on the side of caution and didn't investigate any outer limits of adhesion. Even so, I was in a high state of exhilaration when we pulled in. This is an exciting machine to ride - and watch. All the sadder then, that the wrangles continue. Even if it means creating a separate CRMC class for four-cylinder classic sidecar horsepower, let's hope we see the Kay MV locked in continuing close combat with the Imps in 1988.

 

Sidecar test

The safe rev limit is 9500rpm

 

Pete Sutton rides the 750cc MV Agusta sidecar with Richard Battison

The 750cc MV Agusta sidecar outfit is under test