Setup info for PVP 251 Motor

Important: Use only fuel supply system with, filter, vacuum pump, regulator & pressure gauge "click here"

Specification

Cylinder and Piston

Cylinder 93 mm. high 

Bore: 54,00   maximum  54,035,

Stroke: 54,5 mm

Piston /Cylinder Clearance:  0.07  mm.
Cylinder diam. Piston
   
54.01 53.94
54.02 53.95
54.03 53.96
Squeeze 0.8 in the front cylinder ( insert 2.25 )

Squeeze 0.85 in the rear cylinder ( insert 2.2 )

Cylinder 91 mm. high. use piston number 3965 

Minimum bore is is 53,025 for piston 53.965 and the minimum clearance is 0.06 mm. 

Insert for cylinder head

The number on the insert 2.2, 2.25, 2.3 and 2.35 is the distance the insert is go down into the cylinder, so by change this you will change the compression and the Squeeze, 

The insert with 2,2-1, 2,25-1, 2.3-1 and 2.35-1  have 0.8 cc smaller volume than the insert without  -1, with this 8 deferent insert  can you find the compression there is maximum for the fuel you use.   

Recommended insert for 91 mm. high cylinder with 102 octane unladed petrol (ELF SK35) or same quality is: 

Front part no. 331 (2.3-1)  Rear part no. 330 (2.25-1)  

If you have detonations then go one step down, Front part no. 330 (2.25-1)  Rear part no. 329 (2.2-1)  

If you not have any detonations can you try to go one step up. Front part no. 332 (2.35-1)  Rear part no. 331 (2.3-1)  

Recommended maximum EGT if you measure 150 mm. out in the exhaust from there the steel start.  580 to 600 Dg. Celsius.

Ignition

Ignition unit: PVL Ignition timing:  5.4 mm before T.D.C. Spark plug:  NGK B10EGP
If you have  problem with it burning a hole in the middle of the piston then Reduce the ignition timing to be twin 5.0 and 5.2 mm. before T.D.C.  I f you have  problem with detonation then increase the volume of the combustion camber 

Rotary valve

Rotary valve timing: model 2006 Opens: 48.5 mm. before T.D.C.   Closes: 27.3 mm. after T.D.C.
Rotary valve timing: model 2007 Opens: 51.4 mm. before T.D.C.  Closes: 28.8 mm. after T.D.C.

Primary drive

  clutch axle / rear crankshaft Reduction
Primary reduction ratio: 58 : 26 2.2308

Gearbox

  Standard  Reduction Part number Number on gear
1 st. gear 32 : 12  2.6666 611 : 512 4949 . 467
New 1 st. gear 31 : 12 2,5833 613 . 512 5904 : 467
2 nd. gear 29 : 15 1,9333 621 : 523 4964 : 4950
3 rd. gear 22 : 14 1.5714 632 : 542 5924 : 5910
4 th. gear 23 : 17 1.3529 642 : 542 5933 : 5910
5 th. gear 22 : 18 1.2222 654 : 554 5954 : 5940
6 th. gear 23 : 20 1.15 663 : 564 5976 : 5966
  Option Reduction    
1 st. gear 31 : 13 2.3846  615 : 514 4944 : 462
2 nd. gear 28 : 15 1.8666 624 : 523 4080 : 4950
3 rd. gear  : 16 1.5 : 544  : 4977
4 th. gear 25 : 19 1.3157 645 : 544 5932 : 4977
5 th. gear  : 22 1.1818 : 556  : 5963
6 th. gear  : 19 1.1052  : 566  : 5965
Gear box oil In primary drive In gear box
Castrol Syntrax 75-90 0.2 Liter 0.4 Liter

Recommended sprocket for motor and rear axle 

Motor: 22 T.  23 T. 24 T. 25 T.  26 T. Rear axle: 29 T. 30 T. 31 T. 32 T. 33 T.

Chain

To not overload the chain use minimum 22 T. on the motor and minimum 29 T. on the rear axle, for front and rear sprocket together have minimum 52 T, so you not overhead the chain. For lubrication of the chain, use Molykote Longterm W2

Fuel supply system

Fuel pump Fuel pressure Pressure Regulator Fuel Filter
Mikuni puls pump 0.15 to 0.18 Atu. Part no. 4010 Part no. 4036

Torque for bolt and nuts 

M6 M8 M18x1,5 M22x1.5 Plug screw 
10 Newton  20 Newton  90  Newton  100 Newton  20 Newton

Petrol (Gasolin) & Oil

Petrol:   Unleaded minimum   octane 102

Elf:   SK35

Oil: 4% mixture 

CIK approved is: Castor Xeramic  or Elf.  HTX 976

Carburetor : PVP 42 mm.

Jet needle Needle jet Main jet edler jet Carburetor piston Needle valve
K24 clip position 3  from top DQ 270 208 to 220 

120 with 44B pilot jet

40 250

 

Carburetor : Dellorto VHSC 39.5

Jet needle Needle jet Main jet edler jet Carburetor piston Needle valve
K24 clip position 2  from top DQ 268 188 to 195 on front cylinder

190 to 198 on rear cylinder 

55 or 

120 with 45 pilot jet

40 250

 

Always Change oil then you open gear box or primary drive

After 4 races weekends or max 3 working hours

Description Qty. Part number
Piston, piston pin, c-clips & Piston ring  2 394, 395 or 396 for 93 mm. high cylinder

or 3965 for 91 mm. high cylinder

Big end needle bearing in rods 2 223
Side washer for big end bearing 4 222
Oil seals between crankshaft and primary drive  2 812
Oil seal behind water impeller  1 806

Also change this after 8 races weekends 

Description Qty. Part number
Rods 113 mm. 2 224
Crankshaft pin 20x50 2 225
Main bearing for crank shaft  4 860
Bearing for end of crank shaft 2 848
Oil seal behind ignition & inside oil seal with water pump   2 806
O-Ring on exhaust 42.52x2.62 FPM 4 770
Bearing in gearbox 6304-C3 2-RS 20/52x15 1 852
Bearing in gearbox 6203-C3 2-RS  17/40x12 1 845
Bearing in gearbox 6203-C3 17/40x12 1 844
Bearing in gearbox 6205-C3 25/52x15 1 856
Oil seal on shift shaft 1 802
Oil seal for clutch drum 1 820
Small end bearing for rod 2 390