Hitachi CG 24EBD Series, Руководство по обслуживанию, Страница: 18 / 88

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• Mounting the piston
Piston [49](49){50}<50>
Pin pullout bolt
Piston Pin [52](52){52}<52>
Hex. socket hd. bolt M4
Round bar 7.8 mm in diameter
(e.g., borer 8 mm in diameter)
Needle bearing (A)
(Crank Shaft Comp.
[58](58) /Crank Shaft {59}<59> )
Cir clip mounting groove
Connecting rod small end
2. Reassembly of the engine unit
(1) Removing carbon
Before reassembling the engine, remove carbon from the head of the Piston [49](49){50}<50> , the
exhaust port of the Cylinder [19](19){19}<19> , and inside the combustion chamber. If the Piston Rings
[48](48){49}<49> fitted in the ring groove on the Piston [49](49){50}<50> cannot move smoothly,
carefully wipe off carbon from the ring groove and side surface of the Piston Rings [48](48){49}<49> .
During cleaning, be careful not to damage the surfaces of the Cylinder [19](19){19}<19> and Piston
[49](49){50}<50> . Also remove carbon from the intake and exhaust ports of Muffler (B) [6](6){5}<5> .
(2) Cleaning the parts
Be sure to thoroughly clean the Crank Shaft Comp. [58](58) /Crank Shaft {59}<59> , Piston [49](49)
{50}<50> , and Cylinder [19](19){19}<19> with gasoline.
(3) Mounting the piston and piston ring
• Insert the Piston Pin [52](52){52}<52> by following the procedure below. (See the figure below.)
(a) Insert the Piston Pin [52](52){52}<52> into the Piston [49](49){50}<50> by about 7 mm.
CAUTION: Do not tilt the Piston Pin [52](52){52}<52> .
(b) Set the J-359 jig (piston pin extraction tool ass’y) to the Piston [49](49){50}<50> , and then set a
hex. socket hd. bolt M4 into the pushing side of the Piston Pin [52](52){52}<52> .
(c) Set the needle bearing to the connecting rod small end, and then cover it with the Piston [49](49)
{50}<50> . (Align the triangular arrow on top of the Piston [49](49){50}<50> with the direction of the
exhaust port of the Cylinder [19](19){19}<19> .) Insert a round bar about 7.8 mm in diameter (e.g.,
borer 8 mm in diameter) into the Piston [49](49){50}<50> opposite the side where the Piston Pin
[52](52){52}<52> is inserted, in order to prevent needle bearing misalignment.
(d) With the round bar 7.8 mm in diameter inserted, turn the pin pullout bolt of the J-359 jig (piston pin
extraction tool ass’y) clockwise, and then push in the Piston Pin [52](52){52}<52> just before the
cir clip mounting groove of the Piston [49](49){50}<50> .
• Use long-nose pliers to fit the tip of the two Cir Clips [50](50){51}<51> into the groove on the Piston
[49](49){50}<50> , and then turn it until the Cir Clips [50](50){51}<51> are completely mounted.
• Align the opening of the two Piston Rings [48](48){49}<49> with the knock pin of the Piston [49](49)
{50}<50> .
• After mounting the Piston [49](49){50}<50> , apply a few drops of 2-cycle oil to the needle bearing.