More stroke allows more cubic capacity, which in turn, means more power. That's why most 200cc motors, whether race or road tuned, turn to long stroke crankshafts. To balance out stroke increase, spacers are set in either at the cylinder base or head.
It's also a simple way to play around with the ignition timing.
With long stroke crankshafts, the stroke pivot is further from the crankcase axel: with 60 mm shafts, 1.5 mm. The additional 1.5 mm pushes over the top and lower dead center. To keep the piston from touching the cylinder head, cylinder head/base spacers can be installed or suitable SIP/MMW cylinder heads can be used. Timing changes in any case. Depending on type of race cylinder, there are several favored combinations which we've put together for you in the technical department.
For the MALOSSI 210cc, the following applies:
1.5 mm base compensation: wide rpm range and high PS, lowered torque coupled with late and sudden acceleration.
1.5 mm head compensation: hefty torque and free wheelies in lower rpm's, lower top speeds. This is SIP's favorite touring combination, especially when coupled with a longer transmission.
These items were formerly known under the product name of 'MEC-EUR', although they were always produced by a firm called 'TAMENI'. The TAMENI crankshafts stand out from the crowd with the obvious attention to detail and use of very precise production methods. The inlet-port timings are identical to those found on the original PIAGGIO PX 200 crankshafts, making these quality components an ideal basis for tuned, road-going PX 200 motor projects.
You also can get them with the inlet porting timings of the racing crankshafts 138°/6° after TDC.
Conclusion: A perfect basis for powerful torque touring motors or rpm hefty PS monsters. For those wanting more, we suggest long stroke flowed shafts.
Long stroke crankshaft / stroke 60 mm / connecting rod 105-110 / 24/25 mm, M12
Long stroke crankshaft, with ø 95 mm (flywheel side), ø 97.9 mm crankweb (disc valve side), partially balanced at 12 o'clock, lower connecting rod bearing = silver bearing, 105 mm connecting rod (125/150 cc) or 110 mm connecting rod (200 cc), 60 mm stroke, oil seal housing 24 mm, bearing housing 25 mm, stump cone with M12 thread, incl. connecting rod bearing.
SIP-TIPP: SIP/MMW long stroke head, MALOSSI 210cc and SIP Road exhaust for touring set up, 1.5mm base gasket, SIP Performance/RZ/DSE exhaust, MALOSSI or POLINI 28-30mm carburettor as basics for sport set up. Try out a variety of base/head gaskets to find the right one for your needs.
Helpful Hint: We recommend the use of SIP PREMIUM flywheel big end bearings (90029000) with these crankshafts. The use of a LOCTITE thread locking gel (Art.Nr.14101000) is also needed when used in combination with performance orientated motor setups.
The above mentioned inlet port timings are measured while looking at the crankshaft with the clutch shaft facing away from the person measuring it. For example '138°/6° after Top Dead Centre' (TDC) means the inlet opens at 6° after TDC and remains open for another 138°.
Please consider that the given inlet port timings are not always 100% accurate, due to the fact that these crankshafts being modified by hand!
