Living with a 2001 Suzuki DR-Z400S

No-one in the office remembers Ian Cobby, but he was a staffer on this magazine a long long time ago

September 2001

Take a long look at this beautiful DR-Z for it will never look like this again.

This brilliant dual-sport bike is about to be transformed into a supermotard, and boy have I got BIG plans for it.

I already have in my clammy hands a full stainless/titanium exhaust from Yoshimura waiting to be fitted and next off I'm taking it over to Raceco in Suffolk (01728) 602101 for the motor to be tuned - more poke is most certainly the order of the day. Plans include skimming and porting the cylinder head, fitting a big flat slide carb, high lift cams and possibly a big bore kit. 425cc anyone?

Then I can get the chassis sorted. A new shock (probably a Fox), shortened and stiffened front forks - might even get them titanium-nitrided for less stiction, now that would be trick. Which reminds me, I need to make a call to suspension guru Dave Parkinson at Race Components (01704) 232631 to discuss getting the final suspension units fully set up.

On top of this, I also need to source a pair of 17" spoked wheels (any offers?), a 320mm front disc and a trick caliper too.

With all this lot done, it'll be time to address the cosmetic side of things so I'll need a catalogue with a load of dead trick DR-Z bits. I've got a few ideas already so hopefully by next month I should be able to show some pics of the bike in a trillion pieces. Can't wait.

November 2001

Well, it's been all engine work this month. Not me personally of course, I shipped the bike up to the boys at Raceco in Suffolk (01728) 602101 for the tuning work.

After stripping down the motor they came to the conclusion that the cylinder head has really good flow characteristics. Raceco have a flow bench and measure how much things like heads, carbs and exhausts flow in CFM (cubic feet/minute). For example the Yoshimura exhaust flows three times more effectively than the very restricted standard pipe (90.5 CFM compared to 28 CFM standard). The head's been ported slightly to tidy up the throats and the carb matched to the manifold. The camshafts have been re-ground to give more lift and longer duration, which has meant the standard shims were outside of the operating tolerances, so they've been modified to suit.

The squish gap (clearance between the piston crown and cumbustion chamber at Top Dead Centre) was fairly wide so this was narrowed by fitting a thinner gasket from the DR-Z400E competition model. Compression is obviously now higher. Next up - unblocking the induction and exhaust sides of the motor. I've spent some dough though - the exhaust comes in at £577.00, the cam regrind £180.00, modifying the shims £20.00 and the big fat 41mm carb inc jets and mounting adapters is a cool £360.00, plus the dreaded VAT.

There's still loads to sort out - wheels, brakes suspension and cosmetics. But we're getting there.

February 2002

At Chez Cobby, it's been a fantastic month of excitingly large parcels arriving...  

The first package arrived from Talon Engineering and it was more exciting and promising than the wife getting a big Anne Summers delivery.

Opening the first box revealed black Excel rims laced to the black anodised talon hubs with stainless steel spokes. These are items of extreme beauty, as is the front 320mm 'wave' pattern disc. Also from Braking (who are imported by Talon) came a sexy front caliper, which bolts straight on. Lovely. And no unsightly conversion brackets either.   Also in the box were all the nuts and bolts to fit the discs and sprockets to the wheels.  The wheels fall into place on the bike, mainly due to the spacers - you know the scenario? Hold the wheel up, hook the chain on, hold the spacers in line, and just as you ease the spindle in a spacer falls out. Not with the Talons, thanks to the captive spacers.

Before the wheels fitted themselves they needed tyres. Some sticky Pirelli EVO Corsas rolled up the drive. I rang around a few places to get some inner tubes, five phone calls later and still no joy, the front wasn't a problem but apparently the rear is an odd-ball size (it's a 160/60 - 17). I finally struck lucky and rang HGB in Ruislip so off I trotted with my wheels.

The next parcel came from Taylor Racing in Wiltshire who import the smart French range of off-road CRD goodies.  I got a tidy ally bashplate. The biggest box by far came from Bert Harkins Racing, the importers for Acerbis, and the contents included some Revolution handlebars.   These are stronger than normal bars because of the longer than normal diameter mounting points. These were rounded off with Acerbis brush guards with dinky spoilers fitted on top. Also hidden in the depths of the box was a black body kit. The tank and rad scoops were painted by a mate-of-a-mate.

Massive thank yous go out to: Raceco - engine work, carb, cams, porting etc (01728) 602101, Talon Engineering - the wheels cost £358.00 for the front, £390.00 for the rear, front disc was £149.80 and caliper, £250.00 (01935) 471508, Taylor Racing - CRD bash plate, £79.99 and CRD frame guards, £39.99 (01249) 657575, Bert Harkins Racing - all the black body kit including spoilers, locking wire, fenders, side panels etc (01582 472374), CPK - Pirelli EVO Corsas approx £220 for the pair (07974) 153967.

June 2002

It's finished and it's the dog's pods. After spending half a day on the dyno at BSD in Peterborough the little 400 is now kicking out a healthy 44.5bhp, a huge leap from its standard 29 ponies.

A recent trip to Ty-Croes circuit in Anglesey gave me two days of solid thrashing with her. After my first session on track I made a few suspension mods, maximum pre-load on the front forks and maximum compression damping, then I dropped the forks through the yokes 20mm. At the rear end I wound a load of pre-load on the shock until all the static sag had gone, compression damping all the way in then back two clicks.

Back on the track and the bike was flying, the amount of corner speed it carried was unbelievable - although I had very little feel from the front tyre. I checked the pressures, 30psi front and back. The sticky Pirellis didn't look like they had been working so I dropped the pressures to 26 front and 28 rear.  Back on the circuit and I could now feel the tyres, and so I could push harder in the turns. 

Considering the DRZ was intended as a 'dual sport' bike, in its supermoto guise the chassis is brilliant. The front brake is nothing short of awesome - the 320mm wave disc, braking caliper, braided hose and Discaciati master cylinder have a real easy time of stopping the lightweight Suzuki.

Normally big brakes on light bikes don't work because they are too sharp and have little in the way of feel, but the Discaciati set-up (16mm master cylinder bore instead of 19mm) equals no problem. My 400 had the legs on all the supermotos I came across on track and now the motor has loosened up a bit it's probably making a few more ponies.

The bike was geared perfectly for Anglesey with a 14 tooth front sprocket and a 43 rear, but on the road and other tracks it revs so quick you keep throwing gears at it until it hits the limiter in top (5th gear) at around 100-105 mph, so I will have to experiment with that.