Kit 86cc Ø50mm MALOSSI MHR BIG BORE for crankshaft long stroke 44mm scooter PIAGGIO Liquid (NRG, RUNNER ...)

Attention, the last bomb on-coupler from MALOSSI MHR, the famous BIG BORE 86cc which is exactly 86.39cc. He is   only intended for the crankshaft reference 5313270   of travel 44mm in axis of 13mm, rod of length 85mm and mark MHR. It is reserved for the most preparatory among you. You will have to align the transfers to the casings, strongly equip the engine and machine the skirt housing in the engine housings because the skirt diameter is greater than the original to pass the 50mm diameter while preserving good strength.

 

MALOSSI indications :

CAUTION : To ensure the rigidity necessary for the thermal unit, the cylinder has an insertion diameter in the crankcase of 56.2 -0.1 / -0.2 mm. So it is necessary to bore the crankcase with 56.7 + 0.0 / 0.1mm boring bar for 21mm depth. MHR gave us the big game, a magnificent cylinder head with polished frustoconical stud which even aesthetically is magnificent with its marks placed in 3D on the stud. The alloy and the treatment used are of the highest range, really very solid, so it is ideal for preparation / finishing unlike SIMONINI nykasil which peels off easily and is rather fragile. Its 50mm diameter piston is reinforced, slightly prepared on the rear for better filling / sweeping and is equipped with a reinforced segment in KDN5 cast iron 0.8mm thick, domed chrome. The cylinder has 7 transfers and a huge bar exhaust, the finish is excellent for such a reduced price on this type of cylinder. The kit is obviously delivered with the reinforced needle cage, reinforced studs, several base gaskets in order to adjust your squish as it should. MHR therefore gave us a real monster of torque with diagrams of 192 ° in exhaust and 132 ° in intake.

 

Data and advice MALOSSI MHR

Exhaust diagrams: 192 °
Intake diagrams: 132 °
Compression ratio: 1: 15.15
Combustion chamber volume: 6.1 cc
Minimum / maximum piston / cylinder clearance: NC
Segment junction spacing: 0.15 mm
Recommended squish: 0.80mm
Advance with original ignition: 16 °
Recommended setting with MHR SELETRA ignition: 2.6 mm
Recommended spark plug: W34 ES-ZU

 

 

You will understand, this kit is one of the most powerful on the market and its assembly / adjustment will require a lot of material, knowledge and a big budget. On the competitions and runs, the others have only to behave, rather look at the official figures announced by MALOSSI MHR:

Displacement: 86.40 cc
2 stroke
Compression ratio: 1: 15.15
Bore: 50 mm
Cooling: "liquid" H2O
Maximum power: rpm 13,600: 29 hp
Max torque: 13,200 rpm: 14.4 kgm
Recommended carburettor: VHST 28mm

 

You will need to provide at least : large carburetion kit in 26mm minimum, reinforced crankshaft MHR reference 5313270 only, ultra reinforced bearings, racing exhaust adapted to the diagrams of the kit, racing ignition with internal rotor… All the same, you will regret that the segment junction passes in front of the rear central transfer because this creates premature wear!

 

The pack contains :

4 studs

pack of base gaskets of different thickness for squish

breech block

cylinder head cover

complete seal pack

reinforced needle cage

reinforced piston d.50mm

reinforced piston pin d.13mm

Reinforced C-piston clips

hard chrome reinforced segment d.50mm thickness 0.8mm

aluminum cylinder 7 exhaust transfers with bar d.50mm

cylinder head screws

maintenance / assembly / user manual

Spare parts :

- Piston

- Segment

- Complete cylinder head

- Cylinder head cover

- Cylinder head stud

- Needle cage

- Piston clips

- Piston pin

- Pack attached

As an option we offer a stage 1 preparation, this preparation is a modification of the channels and the exhaust port by increasing the diagrams and improving the duct, it increases the performance of the cylinder. An improvement to the piston and the bottom of the skirt is also included in this modification. Allow a little extra time for this preparation!

Installs on motor scooter PIAGGIO / GILERA Liquid 50cc 2 times:

APRILIA SR (carb.) 50 2T LC 2004 (PIAGGIO engine)
ARPILIA SR R (carb.) 50 2T LC (PIAGGIO engine)

DERBI GP1 50 2T LC
DERBI GP1 OPEN 50 2T LC
DERBI GP1 REVOLUTION 50 2T LC

GILERA DNA 50 2T LC
GILERA RUNNER SP 50 2T LC before 2005
GILERA RUNNER SP (carb.) 50 2T LC after 2006 (C451M)
GILERA RUNNER 50 2T LC

PIAGGIO NRG EXTREME 50 2T LC
PIAGGIO NRG MC2 50 2T LC before 1997
PIAGGIO NRG MC2 50 2T LC after 1998
PIAGGIO NRG 50 2T LC
PIAGGIO NRG MC3 DD 50 2T LC
PIAGGIO NTT 50 2T LC
PIAGGIO NRG Power DD 50 2T LC
PIAGGIO QUARTZ 50 2T LC
PIAGGIO ZIP SP 50 2T LC after 2001
PIAGGIO ZIP SP 50 2T LC before 2000
PIAGGIO Zip sp2 50cc LC

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