O.S. engine MAX-91SX-HRING C Spec PS VIPER, Owner'S Instruction Manual

6

Notes on installing cooling   fan and clutch

Do not use a tool which 

locks  piston  when 

installing a cooling-fan 

and  clutch,  or  top  of 

the  piston  may  be 

damaged.  Also, do not 

insert a screw driver or 

the  similar  into  the 

exhaust port.

It  is  recommended  to  use  Crankshaft 

Clamp 7091 (Code No.71530500) available 

as an optional tool. 

It is made of durable engineering plastic 

and locks the crankshaft without risk of 

damage to any part of the engine.

Application is as follows:

Remove the crankcase rear cover plate from the 

engine and rotate the crankshaft to the bottom 

dead center (BDC) position.

Insert the crankshaft clamp so that its grooved 

portion surrounds the crankpin and lower end of 

the connecting rod and securely tighten the fan 

or clutch onto the crankshaft.

Insert this groove onto

the connecting rod.

BDC position

Rotate the crankshaft so that the

connecting rod comes to this position.

7

Note on installing the engine

Note on heating the glow plug 

Cooling  fan  cover  from

some helicopter  models

interferes  the heatsink 

head. In this case, cut out

the cover as illustrated.

Example

Cut out according to the heatsink head.

Heatsink head, crankcase and cover 

plate of the engine are treated with 

Alumite  which  does  not  conduct 

current.  Therefore,  when  heating  a 

glow plug, connect one lead to the 

glow plug and the other to the head 

of cover plate fitting screw.

First, heat the center plug and start the

engine. Then, heat the second plug while

running the engine at idle. When the

second plug is ignited, idling sound

changes. After confirming this change,

disconnect battery lead to the plugs. If

the idling mixture is rich, it is necessary

to heat the second plug for about 5-10

seconds to ignite. Carefully listen to the

idling sound to confirm the change.

Example