Flashback | 2001 Suzuki RM125 | Suzuki RM250

Flashback – 2001 Suzuki RM125 RM250 details released

16 years ago this week Suzuki unveiled a big revamp for the Suzuki RM250 and RM125 for the upcoming 2001 model year

The frames on both the RM 125 & 250s for 2001 were newly designed to reduce weight by around 580grams.

Steering head had been reviewed to improve cornering and straight line stability.  On the RM 250 rake angles changed from 27° to 27.5° and trail was extended from 111mm to 115mm.  For the 125 rake went from 27.75° to 26.5° while trail went from 114mm to 104mm.

Downtube size was changed from 50mm x 45mm x 1.4mm to 40mm x 45mm x 1.4mm in order to reduce weight for both the 125 & 250. Coupling-press type body frames instead of tube body frames were introduced to increase rigidity and to improve stability. Seat rails were now 120grams lighter.

The footrests were relocated, 9mm rearwards and 9mm upwards to improve riding position for the 250.  No change in this area was undertaken on the 125.

Front wheel hub width reduced from 102mm to 82mm.  The axle spacer material went from steel to aluminium in order to save weight while the outside diameter was up to 26mm from 25mm.  These changes resulted in 48grams being shaved from the front wheel hub.

The cutouts on the front brake were updated in their design which lightened the show by another 100grams.  The thickness of the rotors remained the same at 3mm along with the outside diameter which went unchanged at 250mm. The rear disc was also redesigned which resulted in shaving 146grams from the rotor.  Thickness was down from 4.5mm to 4mm but the outside diameter remained unaltered at 240mm.  The reservoir tank for the rear brake master cylinder was relocated which eliminated the need for a cover to protect it resulting in a 110gram loss. Also on the rear brake side the pedal lost 90grams on the 250 and 78grams for the 125.

Chain adjuster blocks were chamfered to lose 3grams.  The chain buffer size lost 5grams while the chain guide dieted down 32grams.

Some other examples that show the absolute attention to detail that Suzuki went to for the 2001 model to reduce weight – Front number plate 37.6grams lighter, front fender down 30grams, rear fender lost 5grams, front brake hose cover down 87grams, rear brake caliper bracket 31grams, chain roller from 40mm to 35mm saving 8grams, throttle cable 22grams, clutch cable 74grams.

2001 Suzuki RM250 in detail

RM 250 forks – Kayaba forks are fitted to the RM250 and the inner tube size has gone from 49mm down to 46mm which has resulted in a 800gram saving.

RM250 rear suspension – The Kayaba system fitted has saved 260grams from the 2000 model.  The cylinder diameter is down from 50mm to 46mm.  The upper mounting system has been changed from ball bearing to needle roller bearings.  Two adjusters have been installed at the compression side adjuster, high-speed adjuster and low-speed adjuster.

The suspension linkage is down from 32mm to 28mm in the aim of improving feel.  Weight of the linkage lever is down by 26grams.  The link rod is down 120grams.

The 2001 RM250 engine produces more power & torque throughout the whole rev range while losing over a kilogram in weight and shrinking nearly an inch in length.

The cylinder head also has smaller external dimensions and has lost 52grams.

The magneto rotor is also smaller which as resulted in the inertia force being reduced from 4.75kilograms per square centimetre to only 3.55.  Crankshaft inertia has been increased from 30.6kilograms per square centimetre to 31.8 in order to compensate for the decrease in the magnet rotor’s inertia.

The main exhaust valve has been redesigned from the single main exhaust valve to a new two-stage two-piece valve.  With the wider main exhaust valves operating range, optimised port timing can be achieved over a wider rpm range.

The carburettor is now a Keihin PWK38TPS.PWJ.BS. which incorporates a throttle position sensor which regulates the ignition timing by taking engine rpm and throttle opening into account.  Throttle response is said to be improved by the 16mm shorter distance between the inlet and outlet on the 2001 model.

The water pump is now an external unit which helped make the engine shorter overall.

Engine oil capacity has been reduced by 100ml.  Crankcase weight is down 410grams.

The shape of the primary drive gear has been changed in the aim of reducing weight.  The clutch pushrod has been changed from a one-piece steel item to a three-piece two-material (steel/aluminium/steel) type to reduce weight.  The shifter pedal is now steel tube.Below is a specification table followed by a whole swag of great images.

2001 RM250 Specifications

• Length 2175mm
• Width 840mm
• Height 1275mm
• Wheelbase 1470mm
• Ground Clearance 335mm
• Seat Height 965mm
• Dry Mass 96kilos
• Engine Single-cylinder 249cc Two-stroke, liquid cooled
• Intake Piston reed valve
• Cylinders 1
• Bore 66.4mm
• Stroke 72.0mm
• Compression Ratio 10.5:1
• Carb’ Keihin PWK38PWJ/TPS, single
• Clutch – Wet multi-plate
• Transmission – 5-speed constant mesh
• Primary reduction ratio – 3.000 (63/21)
• Gear ratios – 1st – 1.800  2nd – 1.470  3rd – 1.210  4th – 1.000  5th – 0.869
• Final reduction ratio – 3.769 (49/13)
• Front suspension – Telescopic, pneumatic/coil spring, oil damped, compression damping force 20-way adjustable, rebound damping force 18-way adjustable
• Rear suspension, 310mm stroke, 454mm of fork oil in each leg
• Link type, spring preload fully adjustable, high speed compression damping force 3-turn adjustable, low speed compression damping force 16-way adjustable, rebound damping force 18-way adjustable, 320mm travel
• Steering angle 45°
• Caster 27° 30’
• Trail 115mm
• Front tyre 80/100-21 51M
• Rear tyre 110/90-19 62M
• Ignition CDI
• Timing 4° BTDC at 1,500 rpm
• Plug NGK BR8EG
• Fuel tank 8 litres
• Oil change 750ml
• Oil change overhaul 850ml
• Coolant 1100ml

2001 Suzuki RM125 in detail

RM125 forks – 47mm Showa forks are fitted to the 125, down from the 49mm units that were seen on the 2000 model.

RM125 rear suspension – Showa supplies the rear suspension for the 125 which has also gone to needle roller bearings in the upper mount.  Full adjustability is maintained along with the 50mm cylinder diameter.  Cylinder stroke is 132mm which is unchanged from the 2000 model while the whole assembly is some 417grams lighter.

The suspension linkage for both the 125 & 250 is down from 32mm to 28mm in the aim of improving feel.  Weight of the linkage lever is down by 26grams.  The link rod is down 120grams.

The 2001 Suzuki RM125 gains power & torque everywhere in the rev-range.

The engine now sits 17° from vertical rather than the 20° angle on the 2000 model.  This results in the straightening of the intake passage which improves charging efficiency and thus power.

The engine is 750grams lighter than that of the 2000 model and is 21mm shorter.

Like the new 250 the 125 also has gone to an external water pump to achieve the aforementioned shortening of the engine.

The magneto rotor is down from 77.5mm to 73.5mm which reduces weight by 55grams.  Inertia force has gone from 4.75kilograms per square centimetre to 3.55.  Crankshaft inertia has been increased from 56.1kilograms per square centimetre to 57.3 in order to compensate for the inertia lost from the magneto rotor.

On the electronic front the CDI has gone on a diet down to 209grams from the 242gram unit that was seen on the 2000 model.

While the 2000 model utilized a Keihin carburettor the 2001 model has gone to a Mikuni TMX38S in the aim of achieving greater throttle response.  The power jet has been eliminated as the new carb’ can keep the same level of gas flow as that of the 2000 model.  The new carb’ is 104grams lighter than the previous Keihin unit.

Exhaust port shape has been changed and with it a new exhaust pipe is now used and is now aluminium in material.

On the transmission front the clutch pushrod has been changed from a one-piece steel item to a three-piece two-material (steel/aluminium/steel) type to reduce weight.

1st and 2nd gear ratios have been changed in the aim of getting a better holeshot.
1st – 2.071
2nd – 1.688
3rd – 1.444
4th – 1.200
5th – 1.053
6th – 0.950

Gear shifting mechanism has been changed from link-type to gear-type in order to improve shift quality.  The shifter pedal is now steel tube.

2001 RM125 Specifications

• Length 2145mm
• Width 840mm
• Height 1275mm
• Wheelbase 1450mm
• Ground Clearance 335mm
• Seat Height 940mm
• Dry Mass 86kilos
• Engine Two-stroke, single-cylinder, 124cc, liquid cooled
• Intake Piston reed valve
• Bore 54.0mm
• Stroke 54.5mm
• Compression Ratio 10.7:1
• Carb’ Mikuni TMX38S, single
• Lubrication Fuel/oil premixture of 32:1
• Clutch Wet multi-plate
• Transmission 6-speed constant mesh
• Primary reduction ratio 3.368 (64/19)
• Gear ratios 1st – 2.071  2nd – 1.687  3rd – 1.444  4th – 1.200  5th – 1.052  6th – 0.950
• Final reduction ratio 4.083 (49/12)
• Front suspension – Telescopic, pneumatic/coil spring, oil damped, compression damping force 22-way adjustable, rebound damping force 20-way adjustable, 310mm stroke, 180mm of fork oil in each leg
• Rear suspension – Link type, spring preload fully adjustable, high speed compression damping force 4-turn adjustable, low speed compression damping force 19-way adjustable, rebound damping force 20-way adjustable, 320mm travel
• Steering angle 45°
• Caster 26° 30’
• Trail 104mm
• Turning radius 2.3m
• Front tyre 80/100-21 51M
• Rear tyre 100/90-19 57M
• Ignition CDI
• Timing 5° BTDC at 1,700 rpm
• Plug NGK R6918B-8
• Fuel tank 8 litres
• Oil change 750ml
• Oil change overhaul 800ml
• Coolant 970ml