Garelli, an Italian manufacturer of mopeds and motorcycles, was founded in 1919 by the engineer Alberto Garelli. The company produced such models as the Super Sport XL, VIP, Eureka Flex, and Gran Sport.
The rubber clutch in Garellis is often the source of problems, especially concerning idling issues. One common problem with the clutch is the melting of the rubber bushings inside the clutch. This can be fixed by removing the melted parts and replacing the bushing with rubber fuel line. The original bushings are OD 11 mm (I ordered a 11 mm OD fuel line but this was too much, 10 mm, maybe 9 is probably better), ID 6 mm, height 7.25 mm. Six of these bushings are required. Also fuel line with an ID of 1/4" and OD of 11/32" will work.
The Horizontal or NOI style engine came on the Sport, NOI, Supersport XL, and possibly other lines. It has a single speed automatic transmission with an internal reduction of 16/71 or 1:0.225. The internal pedal ratio is 27/9 or 1:3. The Supersport XL LTD two speed came equipped with a VIP style two speed transmission, though it is exceptionally rare.
Bearings and seals for the NOI:
- Mag side crank seal - 17 x 30 x 6/6.5
- Clutch side crank seal - 17 x 30 x 4.5/5
- Drive shaft seal - 17 x 30 x 4.5/5
(the same size can be used for all three if 6.5 width is unavailable)
- Pedal Shaft Seals (x2) - 16 x 20 x 2.5
- Crank bearings (x2) - 6203/C3
- Main shaft bearings (x2) - 6203/C3
The NOI also has a notoriously small woodruff key on the magneto-side crankshaft. The nominal size for these is 2mm by 7mm, W x B.
Bearings and seals are as follows:
- Mag side crank seal – 17 × 40 x 7/7.7
- Clutch side crank seal – 17 × 40 x 6
- Drive shaft seal – 20 × 42 x 7
- Pedal crank seals (2x) – 16 x 24 x 4
- difficult to find, 16 x 24 x 5 worked for me 
- Crank bearings (x2) – 6203/C3
- Main shaft bearing – 6203/C3
- Main shaft Needle bearing – HK 1312
- Drive shaft bearing – 16004
- Drive shaft bushing – brass, with oiler cuts. 20× 24 x 14
- Magneto Side Woodruff Key
- Width: 2.5mm
- Height: 3.7mm
- Length: 10mm
Garelli sold bikes with NOI style engines with 17, 20, 25, and 30mph top speed ratings. These different speeds were accomplished through a variety of means, including cylinder port area, head design, intake variance, various carbs and jettings, gearing, spark plug type, exhaust header diameter and shape, muffler restriction, and piston crown shape.
The cylinder generally seen on a NOI style engine is rectangular and cast iron. Like most Garelli jugs, these came in two varieties -- the "Red Dot" fast cylinder and the "Yellow Dot" slow cylinder -- with matching intake manifold|intakes. The porting difference is small, though the intakes are very different. The "Yellow Dot" or "Square Guy" intake bends on a 45 degree angle, while the "Red Dot" or "Curvy Guy" intake curves up without any sharp bends. These dots can be found by looking at the top of the intake flange, looking down so as to see through the bore. They can also be found on the underside of the flange on the intake itself. They are not always present as they were only painted on and can wear off.
Garelli also made an aluminum version of their rectangular cylinder and a noticeably different ported radial cylinder with accompanying radial head. There is also a flat top and bottom aluminum-type cylinder with more fins which does not fit with the general style of the above mentioned. While nearly all other Garelli cylinders seem to be stamped "CH-3.0," this last type is stamped "CH-1.2."
Piston crowns can either be flat, yielding lower compression, or domed giving higher compression.
Most NOI style engines came with a Dellorto SHA 14/12, though a few came with a SHA 14/9.
The Garelli Katia came with a slightly scaled down version of the NOI. While all parts are the same in proportion, the scale is such that very little is interchangeable.
Care and Maintenance
Regardless of engine type, Garellis require 13.5oz of SAE 30 non-detergent motor oil in their transmission.
If your Garelli came with the oil injector pump, it is advisable that you either test it periodically or remove it entirely and run premix. The seals in these pumps can fail with age, causing vacuum leaks that reduce the actual amount of oil making it into the gas tank. Running oil lean can lead to seizure of an engine.
Manuals and Resources
- Garelli manuals - Garelli owner's and engine service manuals for a variety of models and years