Setup info for PVP 251 Motor
Important: Use only fuel supply system with, filter, vacuum pump, regulator & pressure gauge "click here"
Specification Print in PDF
Cylinder and Piston
Cylinder 93 mm. high
Bore: 54,00 maximum 54,035, Stroke: 54,5 mm |
Piston /Cylinder Clearance: 0.07 mm.
|
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 | Rotax number on gear | |
1 st. gear low | 32 : 12 | 2.6666 | 611 : 512 | 4949 . 467 |
1 st. gear medium | 31 : 12 | 2,5833 | 613 . 512 | 5904 : 467 |
1 st. gear high | 31 : 13 | 2.3846 | 615 : 514 | 4944 : 462 |
2 nd. gear low | 29 : 15 | 1,9333 | 621 : 523 | 4964 : 4950 |
2 nd. gear high | 28 : 15 | 1.8666 | 624 : 523 | 4080 : 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 low | 23 : 20 | 1.15 | 663 : 564 | 5976 : 5966 |
6 th. gear high | 21 : 19 | 1.1052 | 666 : 566 | 5975 : 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 ø20x50 | 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 ø42.52x2.62 FPM | 4 | 770 |
Bearing in gearbox 6304-C3 2-RS ø20/52x15 | 1 | 852 |
Bearing in gearbox 6203-C3 2-RS ø17/40x12 | 1 | 845 |
Bearing in gearbox 6203-C3 ø17/40x12 | 1 | 844 |
Bearing in gearbox 6205-C3 ø25/52x15 | 1 | 856 |
Oil seal on shift shaft | 1 | 802 |
Oil seal for clutch drum | 1 | 820 |
Small end bearing for rod | 2 | 390 |