Mash Dirt Star Scrambler 400




Make Model.

Mash DirtStar Scrambler 400




Four strike, single cylinder, SOHC, 4 valves


397 cc / 24.2 cu in

Bore x Stroke

85 x 70 mm

Compression Ratio

Cooling System Air cooled
Lubrication System Dry sump
Exhaust Two-into-one


Siemens 2.0 EFI


Digital electronic



Max Power

21.6 kW / 29 hp @ 7000 rpm

Max Torque

30 Nm / 3.06 kgf-m / 22.1 ft-lb @ 5500 rpm


Tubular steel frame


Wet, multi-plate



Final Drive


Front Suspension

41 mm Hydraulic fork, adjustable

Rear Suspension

Mono-shock, adjustable  preload

Front Brakes

Single 280 mm disc, 2 piston caliper

Rear Brakes


Front Tyre


Rear Tyre



Length: 2130 mm / 83.8 in
Width:   740 mm / 29.1 in
Height: 1130 mm / 44.5 in

Seat Height

780 mm / 30.7 in

Dry Weight

151 kg / 333 lbs

Fuel Capacity 

13 L / 3.4 US gal / 2.9 Imp gal


  • Fork diameter 41mm – black, with boot protection
  • New upgraded shock absorbers
  • Square swing arm
  • "SCRAMBLER" tyres
  • Rounded side panels
  • Black wheel rims
  • Stainless steel front brake pipe
  • New front light (with stone guard)
  • Front number plate
  • Rubber handles
  • New seat design
  • Rear circular Led light
  • New design, black front mudguard
  • Black rear mudguard
  • Kick starter rubber
  • Vintage MX chromed handlebars

The Mash, at 29bhp, has no trouble maintaining a comfortable pace and is a real pleasure to ride.

All is not entirely rosy in the garden, however. The achingly fashionable minimalist mudguard on the front wheel is utterly useless in keeping road muck off the bike and this machine is destined for winter commuting duties. I took a look at the front mudguard on the road-going sister model, but that seemed only marginally larger.

So, into the Hitchcocks’ catalogue to see what’s available for a 19 inch wheel (the Mash front wheel has the same dimensions as the Bullet). I fitted the Hitchcocks’ stainless steel trials mounting bracket with an unpolished alloy guard. It took a couple of goes to get the wheel/mudguard spacing looking right, but I’m happy with the results for road use. If I were regularly venturing into the mud, I’d prefer at least another inch of clearance, but it has sufficed so far. I’m sure the original stylist is spluttering into his cappucino, but I prefer a mudguard that does the job.

What else? The headlamp was an awesome 35/35W tungsten item that seems to annoy the darkness rather than cutting through it (darkness is not in short supply in winter at these latitudes). Good lighting is a fundamental I am reluctant to relax. On the off-chance that the little mesh stone guard fitted in front of the headlight was stopping 30 of the available 35 watts, I removed it. No difference in the light output, but the lens was easier to clean (and by now I am on the stylist’s hit list, so I have nothing to lose).

I took the headlamp apart to see if it could be converted to a meatier halogen bulb, but no such luck – the support for the 35/35W bulb would not accept anything else. Paul Goff, that gentleman of Amps, lists a 5.75 inch Lucas headlamp with a standard H4 60/55W halogen lamp. The Lucas unit slots straight into the available space and (mostly) shares the bike’s wiring colour-code.

After I discussed this change with Dave Angel, he recommended the Mazda Nightbreaker filament (standard H4 mounting and connections) – he has changed his four-wheel fleet to use only this lamp. The difference is startling, a real benefit. I was concerned about the increased power consumption; the original lamp would have drawn around 3 Amps on either beam. The Lucas unit draws roughly 5 Amps. The wiring to the headlamp appears sturdy enough to cope and is in excellent condition, of course – I’ll monitor it for signs of distress.

Completing the lighting changes, I swapped the taillight for a 19-LED Miller replica, just because I liked the look and the STOP caption in case there is any ambiguity around the bright red light.

I added a ScottOiler E-System to give the chain an easier life. This revealed a problem with the 12V supply, as the battery voltage was dropping below the ScottOiler’s operational threshold upon engine starting, so the ScottOiler was re-booting at every start, requiring all settings to be re-entered. This was mid-January and I felt rebooted myself most mornings, requiring re-input of a couple of coffees for continued operation, so I had to sympathise.

Paul Goff came to the rescue once more. He listed an absorbed glass mat battery with an astonishing power density. This battery measures just 4.5 x 4.5 x 2.75 inches and can support a 130A load. It fitted neatly in place of the original, requiring some wooden packing for a stable fit. The ScottOiler is now a very happy bunny, enjoying a rock-solid 12V supply under all conditions. Engine starting is also improved.

The Mash’s engine and gearbox are great, requiring nothing from me but a regularly-changed supply of clean oil (Dave Angel stated that the Honda XBR engine upon which the Mash unit is based was likewise fussy about clean oil; bottom-end longevity suffered if this was not observed). The oil capacity seems ungenerous – perhaps a design area to look at in future; I would not be surprised if overheating was an issue in warm climates.

I have noted a number of new models based around variants of this engine in off-road-going running gear; obviously Mash are ‘in the zone’ with this line. Some may baulk at making such changes to a brand-new machine, but all engineering products are compromises. The Mash developers are bringing a machine to market within tight constraints of performance and budget. I don’t need to live with some of the required compromises; better components are available and will improve my enjoyment of the machine. As I’ll be riding the Mash for many years to come, I look on these modest changes as an investment in a market-priced machine.

By the way, the exhaust bark deserves to be released as a Christmas chart-topper!

Source:Real Classic, written by Ian Mitchell