MZ BK 350 Information

A very interesting motorcycle produced between 1952 – 1959 in East Germany. It was first named IFA BK 350 and than renamed in MZ BK 350 in 1956 when the brand Motorradwerk Zschopau was introduced. It is currently the only motorcycle with a two stroke boxer engine (there is also a scooter but we like motorcycles :) ).

There are two versions of the motorcycle, the 15 HP and the 17 HP, with slight differences at the cylinders and air intake.

Here are some goodies i found on the internet*:

IFA / MZ BK 350 Engine schematics diagram

engine

IFA / MZ BK 350 Gearbox schematics diagram

gearbox

IFA / MZ BK 350 Rear-wheel Drive  schematics diagram

reardrive

Working procedures 15 HP version 17 HP version
Working procedures Two-stroke Two-stroke
Stroke 65 mm 65 mm
Drilling 58 mm 58 mm
Number of cylinders and arrangement Two cylinder boxer engine Two cylinder boxer engine
Capacity 2 x 171.7 cm ³ = 343.4 cm ³ 2 x 171.7 cm ³ = 343.4 cm ³
Compression ratio 6.5: 1 7.1
Conurbation 31 cm ³ 28.5 cm ³
Power at 5000 rev / min 15 hp 17 PS
Maximum torque at 3000 r / min 2.7 kgm 2.7 kgm
Cooling Air (wind) Air (wind)
Timing
With suction tip 120 degree crank angle 120 degree crank angle
Suction tip without 104 degrees crank angle 104 degrees crank angle
Overflow 116 degrees crank angle 116 degrees crank angle
Outlet 136 degrees crank angle 136 degrees crank angle
Carburettor
Number 2 2
Make IFA BVF NB 22-7 IFA BVF NB 22-1
Setting
Intake 22 mm 22 mm
Main Jet 95 95
Leerlaufdüse 030 30
Needle jet 67 67
Needle position III III
Position of the idle air screw 2 … 2 ½ rev open 2 … 2 ½ rev open
Gas valve design section 14 14
Air Filter 115 mm diameter 120 mm diameter
Lubrication Mixture lubrication (oil mixing ratio: 1 Fuel: 25) Mixture lubrication (oil mixing ratio: 1 Fuel: 25)
Ignition
Construction Battery ignition Battery ignition
Spark plug Insulator M 14-225 Insulator M 14-225
Thread length 10 mm 10 mm
Electrode spacing 0.55 mm 0.6 mm
Breaker-distance 0.4 mm 0.4 mm
Ignition timing adjustment automatically d flyweights automatically d flyweights
Preignition 3rd .. 3.5 mm BTDC at full open flyweights 3 mm BTDC at full open flyweights
Coil
Number 2 2
Piston
Oversize f Cylinder Ø 58, 58.25, 58.50, 58.75, 59 mm f Cylinder Ø 58, 58.25, 58.50, 58.75, 59 mm
Piston rings 191 g 3 per flask
Kind 3 per flask Compression rings
Crankshaft bearings Compression rings
Number 2 2
Type WJL front 25, rear 6305 WJL front 25, rear 6305
End Bearings doppelrollig without cage doppelrollig without cage
Greatest length 2150 mm 2150 mm
Greatest width 760 mm 760 mm
Greatest height 1000 mm 1000 mm
Wheelbase 1400 mm 1400 mm
Turning circle 4400 mm 4400 mm
Ground clearance 140 mm 140 mm
Operation Ready weight 142 km dry 142 km dry
Weight with fuel 154 kg 154 kg
Gross vehicle weight
Solo 330 kg 330 kg
Fuel consumption at 80 km / h = 3.85 l/100 km at 80 km / h = 3.85 l/100 km
at 100 km / h = 5.0 l/100 km at 100 km / h = 5.0 l/100 km
at 115 km / h = 6.0 l/100 km at 115 km / h = 6.0 l/100 km
Wheels
Kind Spoked wheels Spoked wheels
Attachment Thru axle Thru axle
Rim Size Drop center rims x 2.5 19 Drop center rims x 2.5 19
Tires
Dimension 3.25 to 19 3.25 to 19
Transmission
Construction allegedly attracts motor-mouth circuit, 3 and 4Helical gear allegedly attracts motor-mouth circuit, 3and 4 Helical gear
Number of gears 4 4
Neutral light electr. Indicator in the headlamp electr. Indicator in the headlamp
Circuit by footswitch by footswitch
Gear ratio
First Gear 1: 3.27 to Mot.-Nr. 1601000
1: 3.84 from Mot.-Nr. 1601001
1: 3.84
Second Gear 1: 2.10 1: 2.10
Third Gear 1: 1.38 1: 1.38
4th Gear 1: 1.07 1: 1.07
Top speed
First Gear 33 km / h 33 km / h
Second Gear 61 km / h 61 km / h
Third Gear 96 km / h 96 km / h
4th Gear 115 km / h 115 km / h

 

* information and photos from mz-b.de , ostmotorrad.de , manualedereparatie.info , wikipedia.com,

 

 

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