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Motori Minarelli

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Motori Minarelli S.p.A was an Italian company founded in the 1950s that produced small engines. Many Minarelli engine parts can be interchanged with Morini Franco Motori engine parts due to the extreme similarities in design and construction.

Types

Some varieties of the Minarelli engines, which are equally awesome:

  • V-1 port-inducted engine. (42mm stroke)
  • V-1KS port-inducted kick-start engine. (42mm stroke)
  • V-1L cased-inducted reed valve engine. (39mm stroke)
  • V-1LKS case-inducted reed valve kick-start engine. (39mm stroke)
  • V-1HS Electric Start.
  • C-2, C-3, and V-2, which are variated engines. (These are more sought after for their elusive and rare existence.)


Variations
It appears that a few later models ('85 and post-'85-ish) have also been seen with a peculiar air-cooled cylinder. These cylinders resemble Puch, or Tomos since the cooling fans are radial rather than stacked. They may also lack the cooling fan and slotted shroud, and is replaced by a non-slotted 'scoop' type shroud. Newer models also benefited from a high-compression head, which is easily distinguished by a larger, more squarish, radial fin pattern. It also features an angled spark-plug hole. Fantic motors had a slight variation of this high compression head, though the fins are less pronounced, and the spark-plug inlet is not angled.

Older models may have a semi-circular crank, with or without a brass bushing in the upper (smaller) end of the connecting rod. New models have full-circle cranks with roller bearings in the upper connecting rod. Both varieties have lower (big-end) roller bearings. Like Carabela engines, Minarellis may even be seen as a kick-start. There are also a few that had built-in 'auto-lubing' system, similar to a Tomos or Garelli 'two-stroke direct injection' systems.

It is important to take note of the fan and shroud system on your Minarelli. They are typically found with two different sizes, maybe more, who knows? Usually older models will have a larger fan, and 3-screw, grey housings, while newer models may be seen with the smaller fan, and 4-screw, black housings.

Restrictions

Some Minarelli engines came with either a 20, 25, and 30 mph cylinder. This is often discovered by measuring the cylinder bore, though other restrictions included a smaller, more constrictive 9mm intake port and intake manifold. Usually they are seen with a forward-facing or bent-style 12mm intakes. Some bore sizes for 20 mph versions are: 38.0mm, 38.2mm, 38.4mm, 38.6mm. Others include: 38.8mm, 39.0mm, 39.2mm, 39.4mm, 39.6mm, 39.8mm, for 25/30 mph versions.

20 mph versions may also have 9-Teeth (TEEF!) front sprockets, while 25 mph versions may have 10T, and the 30 mph might have 11T. Rarely, they may even have 12T or 13T. Non-variated bikes may have anywhere from 38-45+ Teeth on the rear sprocket, which could restrict certain rpm ranges as well.

Also, there appear to be many versions of exhaust systems including, but not limited to, a typical, linear pipe, a 'pancake' exhaust that mounts seamlessly on the underside of the engine (most engines have a small bolt on the left hand, bottom side of the engine for this exhaust), and a beefier, Bi-turbo-esque pipe that even has a heat shield attachment. Tomos and Puch pipes are among a few that can be adapted to fit these engines, but usually require the fitting of an exhaust bracket on the the frame.

Electrical

Most Minarellis had CEV (6932 or 6876) magnetos (6v 23w), though some Minarellis were equipped with Bosch (KB6-B212) systems (6v 18w). Part numbers and specs were taken from the V-1 Repair Manual.

Bearings and Seals

The V-series engines use:

  • 2 main bearings for the crankshaft, size 6203, non-shielded. 17 X 40 X 12
  • 2 output shaft bearings, size 6202, non-shielded. 15 X 35 X 11

In the bearing biz these are known as "open deep groove ball bearing with a C3 internal clearance".

The connecting rod uses two sizes of needle bearings.

  • Upper (small end) bearing size is 12 X 15 X 15.
  • Lower (big end) size is 12 X 22 X 16.

The crankshaft uses 2 seals on either side to cover the main bearings.

  • 17 X 35 X 8 (17 X 35 X 7 can also be used).

The output and pedal shafts require 3 seals.

  • 15 X 24 X 5.

One is placed over the output bearing behind the drive sprocket (be careful...this is a real bitch to put in without fatally damaging the seal), and the others are placed on either side of the pedal shaft. Numbers face outward on all seals.

Specifications

Torque

  • Engine studs and case bolts should be torqued at 7.3-8.7 ft/lbs.
  • Intake and exhaust should be torqued 7.3-8.0 ft/lbs.
  • Magneto should be torqued to 33.3-34.7 ft/lbs.
  • Drive sprocket should be torqued 31.8-32.6 ft/lbs.
  • Clutch should be torqued at 21.7 ft/lbs.

Note: These specs are taken from the Minarelli v1 service manual.

Spark plugs
NGK B5HS or B6HS gapped at .024 inches

Use a B5HS for colder weather, and a B6HS for hotter weather or kitted bikes. B7HS may also be used for kitted bikes, but should be used only when needed. A 'colder' plug won't prevent your bike from over-heating and exploding. Champion L86 or L89CM Bosch W 145 TI (does anyone use these anymore?)

Performance

Main article: Minarelli performance

Minarelli engines are super rad, and have a very dedicated following. Ride one, and you will understand. They are very reliable, offer a lot of torque, and are generally easy to troubleshoot.

Weaknesses
One (and in my opinion, the only) downfall of these engines are the starter-clutch mechanisms. They are similar to a Puch design, except the center of the starter-clutch is equipped with a stationary ball-bearing rather than a flat disk. This bearing tends to wear out and fail, especially if there is excessive use of the clutch lever while the engine is in operation. Other components of the starting-clutch that may fail are one of two leaf springs that attach to the inside of the clutch cover, which should be checked and replaced in case of excessive wear. Other than mentioned above, it is safe to say that these engines are bullet-proof.

Aftermarket parts
There are plenty of aftermarket parts, including, but not limited to:

  • Kits: 55cc Kits (unknown manufacturer) 64cc Kits (Autisa? rare) 75cc Kits (Polini) 80cc Kits (BRN, Bennassar, Imperial, etc) 90cc Kits (BRN, Bennassar, Imperial, etc)
  • Clutches: 2-shoe and 3-shoe centrifugal spring, centrifugal rubber, and/or washer-tension clutches (centers of clutches may need the tapers reamed in order to work on most common Minarelli engine types)
  • Exhausts of all shapes and sizes: 80cc and 90cc (CV Racing, Bennassar, etc)
  • Cranks: Full-circle racing cranks (will need gasket modding to correct port timing in most engines)
  • Electrical components: CDI's, including auto-advancing and auto-retarding CDI's (will need a lighting option to run lights-CDI works in the ignition circuit only)
  • Fuel system: Carburetors and intake manifolds designed for bore kits

The list goes on...if you need it, they probably have it somewhere.

Manual


V1, V1L and V1HL exploded views with parts lists. [1]

Mopeds with Minarelli Engines

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