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Idiomas disponibles
Idiomas disponibles
ASSEMBLY INSTRUCTIONS
DERBI SENDA R 50-70 cc
We thank you for choosing our articles and stay at your disposal for any further information you may require.
• Clean carefully the engine area.
• Empty the cooling circuit.
• Remove carefully the exhaust system, the reed valve and the original cylinder.
• Cover the casing mouth and remove the piston. Be careful that foreign bodies do not enter the casing.
• Check carefully the wear of the following components, as the power increase in the kit Ø 47,6 can compromise their characteristics:
- crankshaft (with the kit Ø 47,6 we suggest to assemble our crankshaft Racing – see catalogue)
- oil seals and crankshaft bearings (with our thermic units Ø 47,6 the engine undergoes an increase in mechanical stress caused by the power increase; as a result, the
original bearings, even if in good conditions, can break. Therefore, we suggest to replace them with bearings clearance C4, order 2 pcs.).
- roller case
- small end
• Wash carefully the new thermic unit and the cylinder supporting surface on the case. Make sure that no gasket scraps or bruises are left.
• Assemble the piston checking that the printed arrow on the head is turned towards the exhaust system. Make sure that the segments enter perfectly their seats.
• Assemble the cylinder by inserting the proper base gasket (see squish).
PISTON ALIGNMENT CHECKING:
• Fix the cylinder (without head) to the base using the proper nuts and putting spacers instead of head.
• Check the alignment connecting rod-cylinder-piston by turning the engine manually. Check that the piston keeps a side clearance in its movement. If not, check that the
casings are well coupled and that the cylinder leans perfectly on them. If these couplings are perfect, this means that the connecting rod is bent. In this case, if you do
not want to replace it, we suggest to insert a pin in the gudgeon pin hole and, without forcing too much, to prize in order to make it straight.
• Remove the cylinder you have temporarily assembled. Insert the segment in the piston. Make sure that the spin locks are perfectly inserted in their seats.
• Lubricate with mixture oil the internal side of the cylinder and replace it carefully.
• Assemble the central dome and the external head with their o-rings by tightening the nuts at 1 kg at crossing using a dynamometric key. Be particularly careful during this
operation as a wrong tightening can considerably compromise the performance and life of the kit (the thermostat cannot be assembled on our cylinder head).
• Fill the cooling circuit up to the level.
• SQUISH: To obtain the best tested performance from this thermic unit it is necessary that the cone-shaped squish is equal
to 0,9-1,3 mm (for the thermic unit 70cc Racing the squish must be equal to 0,8 mm), see picture. Check the squish by starting with
the base gasket 0,5 mm thick inserted in the kit. To measure it, act as follows: place the piston manually towards the bottom dead
centre. Insert a tin thread of 1,5 mm thick in the spark plug in axis with the gudgeon pin. Turn manually the flywheel clockwise in
order to put the piston to top dead centre (for at least 3 times). The tin thread will show a crush that, measured with a centesimal
gauge, indicates the squish value. If the squish value does not correspond raise or lower the cylinder by replacing the base gasket
with the ones supplied in the kit.
• ELECTRONIC UNIT: check the spark advance, especially if the electronic unit has been replaced, which should be the one
indicated by the manufacturer.
• INTAKE SYSTEM: Check particularly that in the reed valve no burrs or material wastes are left. With the thermic unit Ø 47,6 we
suggest to assemble the increased carburettor and reed valve (see our catalogue).
• EXHAUST SYSTEM: check that the exhaust system is in perfect conditions. We remind you that during the assembling the muffler
must not be forced. To avoid this, use the spacers.
First of all check the carburation. Use petrol containing at least 96 octanes and synthetic oil. Do not force the engine during the first
250-300 km as you can cause damage to the cylinder kit. The best performance is obtained only after a good running-in.
We advise to clean all these parts from the residuum after combustion every 3000 km.
Check that the rings are not blocked and control their wear.
As soon as you feel that the engine power is decreasing we suggest to replace the piston in order not to compromise the roundness
of the cylinder tube.
We remind you that it is not the single part but all the parts as a whole that give your engine the best performance!
The assembling of the article/s included in this kit must be made only by qualified technicians. In case any faults and/or problems are caused by a wrong assembling, we
will not be responsible for any damage or technical or economical request which are claimed to us.
The descriptions contained in this leaflet are not binding. Athena reserves the right to make any changes, if necessary. Are not responsible for any printing errors.
All ATHENA products, which are manufactured with higher displacement and power than those permitted by law of the country where the end user lives, are
intended solely for competition-sports usage. Use on public roads as well as in aeronautics and marine is prohibited. ATHENA is not responsible for any
different usage. The customer takes full responsibility that the distribution of the articles purchased from ATHENA is in line with the current regulations of his
country and therefore frees ATHENA from whatever responsibility in this matter.
FIM/G017
ATHENA SPA - Via delle Albere, 13 - 36040 Alonte (VI) - Italy - Tel. +39-0444-727258 - Fax +39-0444-727222
http://www.athena-ad.com - e-mail: sales@athena-ad.com (for foreign markets)
TEC. INFORM.
Ø 47,6
PRELIMINARY INSTRUCTIONS:
ASSEMBLING INSTRUCTIONS:
RUNNING-IN, USE AND MAINTENANCE:
BORING
STROKE
Ø 40
40 mm
40 mm
47,6 mm
40 mm
CUBIC CAPACITY
COMPRESSION RATIO
50 cc
13,3:1
70 cc
13,5:1
GB
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