YAMADA DZ185 Operator's Manual

57

137

14

120

68.5

149.5

63

25

58

115.5

Tube A

Air

Tube B

Fuel Tank Clunk

Regulator

Front Nut（HEX13）

Rear Nut（HEX13）

Front Mount

Rear Mount

Fuel Filter

Needle Valve

Break-in Needle

Safety Instructions

In order to use the engine, please read through this instruction manual care-

fully. This is a complex, high-performance engine. If you have any difficulties 

for understanding any part of this instrucyion manual, please contact the 

hobby shop from whom you purchased the engine, or contact us directory.

1. The propeller double locknut assembly supplied with the engine must be          

used when mounting the propeller.

2. Select a good quality propeller and follow the manufacturer’s instruction.

3. Choose a propeller size that will not allow the engine to exceed the maxi-

mum practical RPM in flight.

4. Always ensure that no people are in front of or besides the propeller while 

thet engine is running.

5. To start the engine, set the throttle to the idle position and use an electric 

starter. 

6. After starting the engine, always move behind the propeller to adjust the 

needle settings.

7. The engine becomes extremely hot both during and after engine runs. Do 

not touch the engine, exhaust header, muffler, or any parts attached to the 

engine while it runs or before it has cooled down.

8. The ignition systtem develops an extremely high voltage, so please be 

careful during its operation. It is very dangerous to modify the ignition sys-

tem by yourself.

9.  Sparking noise may cause interference and shorten the rangr of the 

aircraft’s receiver. Please perform a range check with the engine running on 

the ground before you fly. If there are any problems with range, DON’tT FLY.

10.  If the engine runs incorrectly, DON’T FLY.

11. Do not use this engine for anything other than radio controlled airplanes.  

Do not use it for radio controlled helicopters.

12. You have full responsibility while you operate the engine. Please be 

extra careful for your safety and the safety of tothers wgenever you operate 

the engine. 

Installation

WE RECOMMEND THAT THIS ENGINE BE MOUNTED ON A SHOCK ABSORB-

ING SOFT MOUNT

1  Connect the engine to the fuel tank and CDI system as shown in fig.1. 

The battery and switch for the CDI unit is not supplied with the engine. The soft 

mount and fuel filter are optional.

2. The recommended fuel tank size is 500cc to 700 cc(18oz to 24 oz). A standard 

clunk type fuel tank may be used. If this type of tank is used, you must use the spe 

cial  clunk supplied with the engine. Please note that with this clunk, some    

fuel  cannot be drained from the tank. As soon as any part of the clunk becomes  

exposed, the engine will stop due to air entering the fuel pump. 

3  Always use a fuel filter. We recommend YS filter ( 6720 ). With this filter, you must  

  remove the cloth portion of the filter and leave both the metal filter screens in place.

Fuel

1. Use a good quality alcohol based model engine fuel containing 10% to  

   25% nitro, and oil content 5% to 25%. You can not use gasoline fuel.

2. When you filling the tank, disconnects Fuel Tube “A”, or Fuel Tube “B”   

   see “Fig.1”  from connecting tube to filling. If you use “T” nipple on the fuel   

  line to filling, use fuel stopper on the Fuel Tube “A” see “Fig.1” to avoid fuel  

   in to the engine.

Propeller

1. Due to the high output power of the DZ185 engine, it is supplied with        

a double locknut system for added safety. Mount the propeller and tighten  

    the rear nut. Next, tighten the front nut. The rear nut has an offset shoul 

    der so the front nut will secure itself to the rear nut. 

2. Please retighten propeller nut periodically.

3. Select a propeller that will allow the engine to run at maximum speed be 

    tween 6,000 to 8,000 rpm range.

4. We recommend sizes 19X11 to 21X10. Other prop sizes may be  

used as long as the correct rpm range.

High Speed Needle Adjustment

1  Adjustment of the high speed is done by the carburetor needle    

valve.When the needle valve is turned clockwise, the mixture  is        

     leaner. When it is turned counter-clockwise, the mixture is richer. 

A good starting position for the high speed needle valve is 2 turns      

open from the fully closed position.  At this setting the engine will    

be very rich and may die when you remove the glow driver.  

If this happens, turn the needle valve in 1/2 turn and try again.   

The final running setting for the high speed needle will be approx-   

imately 1 to 1-1/2 turns open from fully closed. 

2  When the engine is started, open the throttle gradually. Next, find    

the peak position ( highest RPM ) by adjusting the needle valve.     

Then the needle valve should be opened approximately 1/8 _ 1/4    

turns from full RPM to achieve best performance. 

Break in needle

Open break-in needle half turn in counter clockwise direction while 

break-in. After break-in, close it to 1/6 turn or fully closed position. By 

this procedure, fuel flows into crankcase through  break-in needle. It 

makes lubrication better and also prevents percolation (vapor rock) . 

We recommend to open it a little under high tempreture in summer time. 

NOTE: Engine power decrease as break-in needle open. When you 

need maximum power, close the needle fully.

Breake-in

1.  Start the engine with high speed needle valve open 1 1/2 - 2 turns  

and the brek-in needle open 1/2 turn from the fully closed position    

      and with the throttle at the idle position. 

2.  After starting the engine, increases the RPM gradually by operating  

the throttle. Do not suddenly apply full throttle. 

3.  If the mixture is too rich and the engine misfires, turn the needle    

valve clockwise to make the mixture leaner. 

4.  Breake-in the engine with one or two tanks of  fuel (500cc) on the   

ground, running at the richest possible mixture setting. 

5.   Close the break-in needle till 1/6 or fully closed position after break-in.

Idling adjustment

1. To get 1,200rpm to 2,000rpm idling.

2. When the regulator is turned counter-clockwise, the idle mixture is leaner.  

   When the regulator is turned clockwise, the idle mixture is richer. Adjust  

   regulator by turn 45 degree at a time.

3. If idle mixture is too rich, gradually rpm drops and stops after continuous  

    idling. If engine stops when you change attitude of airplane on the ground  

   also too rich on idle mixture. If mixture is too lean on idle, rpm is go up      

   and down and not keep stable when you make continuous idle. 

Glow Plug

Select the most appropriate glow plug from those designed specifically for 

4 cycle engines. Glow plug selection greatly affects the maximum engine 

output and low idle. If RPM’s decrease or stop when the booster cord is 

removed, replace the plug. We recommend the YS#4 plug for maximum 

performance. 

Tappets Adjustment

1. Tappet clearance is preset at the factory.

2. Clearance adjustment may need after first one hour running time due to   

    initial wear. After first adjustment, clearance should be checked as normal    

    maintenance for every 10 hours running for maintain maximum perfor

    mance.

3. Clearance adjustment should be done when the engine is cool.

4. The proper clearance should be set at 0mm (0.000”) to 0.1mm (0.004”).  

    The adjustment is achieved by loosening the lock nut see “Fig.2” and    

    turning the adjustment screw see “Fig.2”. The engine must be at top    

   dead center on the compression stroke before any adjustments are made.  

   This engine runs best with the valves set at a tight setting. If the valves  

    are set too loose, power will be affected.

Cam Gear Timing

If for some reason you have to disassemble your engine, please follow 

these important steps on reassembling the cam gear.

1. Remove the carburetor and back plate assembly. Notice the impression  

    mark or dot opposite the rod journal on the crankshaft.

2. This mark is to point straight down or lined up with the outer case seam  

    line at the bottom and hold crankshaft securely.

3. Reinstall the cam with the dot facing you. After you fully installing cam     

   and then check dot should be pointing straight down will give you right    

    timing. 

Operation of YS Super Mount (Option)

1. It is hold by 4 screws, 2 on the front ring and 2 on the rear soft mount. 

    There are two different height of spacer we provide.  

        A set spacer  (MN110S) :  10mm thickness

        B set spacer  (MN111S) :   4mm thickness

2. Please be sure not to hit any part of the fuselage by the engine after it     

    installed.

3. If damper oil is leaked, refill TAMIYA damper silicon oil #600. Damper is a  

    consumption parts, please exchange if you fined worn or some defect. 

Cleaning

This engine is using silicon gaskets, “O” rings etc. Please use methanol or 

model engine fuel for cleaning. Do not use Kerosene, Gasoline, Machine 

oil, Automobile parts cleaner or house hold lubricants to clean. It will harm 

silicon parts.

Engine Cooling

Be sure to secure cooling air for engine cooling. If it is not enough cool-

ing air for the engine causes heat up the regulator and carburetor to make 

vaporized or percolates the fuel and will get deteriorations of engine perfor-

mance or stop the engine. Please read carefully below for provision.

1. Please open air intakes and outlets as big as possible.

2. Take off cowling when you make long engine adjustment included idle 

   adjustment. When air temperature is high, it may heat ups the regulator  

   and carburetor to make vaporized or percolate the fuel even with out cowl 

   ing. If it happens, wait till engine well cooling down before you restart and  

   adjust.

Rusting provision

Do not leave fuel in the engine after you finished for day. If you store the en-

gine long period of time, few drops (about 1cc) of model engine lubricant oil 

from carburetor and clank several times. Do not use Automobile engine oil. 

They will not mix together with alcohol. 

Parts and Repair Service

If you can not find repair parts form hobby shops, you can order parts direct 

to our factory.  We also do repair your engine at our factory. If you need 

repair service, please make detailed of states and send together with the 

engine.

Warranty

We strictly inspect each process of production from parts to final assemble 

for keep good quality.  If a performance deteriorates or part fails due to a 

manufacturing error under normal usage will repair no charge with in 1 year 

starting from the date of purchase. Warranty will not cover normal wear. 

Even with in 1 year warranty term, improper disassemble or assemble, un-

der improper usage, any modification will avoid this warranty and there will 

be normal charge for parts and labors. 

FIG 1

Fig2

DZ185

 Bore 

    35mm

 Stroke 

    31.8mm

 Weight 

    960g 

 Displacement      30.6cc

 Practical rpm      1,000~9,000rpm

OPERATOR'S MANUAL

Tappet Clearance