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Official Hummer H1 Build Diary - Stages 57 - 65 Options
#1 Posted : 27 January 2014 18:05:09

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Stage 57 - Contains the cylinder sleeve and piston.

Carefully slide the piston with its connectiing rod out from the bottom of the cylinder sleeve.

Inspect the cylinder sleeve. There are four rectangular holes in its sleeve, but only one with a bevelled lower edge - called the the intkae port which is at the front of the sleeve.

Directly opposite the intake port is the rear port, through which exhaust gas is ejected.

There are two smaller ports on either side of the sleeve. These are scavenging ports.

Holding the crankcase assembly, rotate the crankshaft so that its connecting pin is at the bottom of the crankcase, known as ‘bottom dead centre’ (BDC).

Carefully slide the piston, connecting rod side first, into the top of the crankcase. Make sure the bottom edge of the piston that has a shallow, curved indent in its face is facing towars the front of the crankcase. Then carefully lift the connecting rod on top of the pin of the crankshaft. Carefully join the parts, but do not force them. Move them from side to side until they fit effortlessly together. Once the parts are fitting together comfortably, press the rod completely onto the pin using your thumb.

Now slowly rotate the crankshaft so that the pin is at the top of the crankcase, with the counterweight at the bottom, ths is called 'top dead centre' (TDC). The piston should be sitting flush with the top edge of the piston chamber.
Now slide the pstion sleeve on to the piston wwith its rear exhasut posr faceing towards the rear of the crankcase. Lower the cylinder into the
crankcase, stopping to check the alignment of the rear port, and at the same time you will notice a slight resistance as you seat the sleeve.

When in place, the cylinder lip should protrude just above the top edge of the crankcase.

Store the assembly within a seled plastic bag.

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#2 Posted : 28 January 2014 09:53:04

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Stage 58 - Contains the cylinder head, gaskets, cap screws and an allen key.

Familiarise yourself with the cylinder head. The central hole in the top will accommodate the glow plug and glow starter, the six smaller holes will be used for the cap screws to attach the head to the crankcase. When viewed from the side, you wil notice that the head has cooling fins designed to dissipate heat.

On the underside of the head there is a raised circular section with a threaded hole at its centre which is the top of the combustion chamber.

Place the first gasket around the raised section at the bottom of the cylinder head. The gasket is very thin, so take care not to bend it out of shape. It does not matter which way round the gasket goes. Then place a second gasket on top of the first.

Position the cylinder head, gasket-side first, onto the top of the crankcase, making sure the gaskets do not fall off, then adjust the orientation of head until your assembly resembles the step image.
With the assembly still in exact alignment, lower each of the six 2.5x14mm cap screws into the holes around the top of the cylinder head.

Lower the longer end of the 2mm Allen key into the first hole, and when it meets the cap screw head, tighten carefully but do not fully tighten until all screws are in place. To complete the tightening process, tighten each screw fully following a diagonal screwing pattern as shown in the instructions.

Store the engine in a sealed plastic bag until the next stage of assembly, and take care not to drop the engine.
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#3 Posted : 28 January 2014 10:17:18

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Stage 59 - Contains the engine backplate, recoil starter shaft, gasket and cap screws.

Fit the gasket over the central raised section of the backplate. It does not matter which way round the gasket goes. Align the four holes inthe gasklet with those on the backplate.

Place the recoil starter shaft into the central hole in the backplate. Then take the crankcase assembly and rotate the crankshaft so that its pin is top dead centre (TDC).
Hold the backplate with its triangular projection to the right, rotate the back of the recoil starter shaft until the notch of its place is facing TDC.

Holding the shaft in place, carefully push the backplate onto the crankcase so that the notch in the plate of the recoil shaft, engages with the cranckshaft pin and that the backplate plate aligns with the mounting holes in the crankcase.
If the gasket gets dislodged as you join the parts, ently adjust its position. It should sit perfectly level with the edge of the crankcase.

Now place the four 2.5x8mm cap screws into the backplate, lightly tighten eac using the 2mm Allen key, then once all four cap screws are in, tighten each fully following the diagonal pattern shown in the instructions.

Store the assembly away safely in a plastic bag until the next stage.
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#4 Posted : 29 January 2014 15:52:51

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Stage 60 - Contains a pre-asembled recoil starter unit, one-way bearing and flange screws.

DO NOT be tempted to pull the the cord of the recoil starter before it has been secured to the backplate of the engine.
At this stage the recoil starter is only temporarily assembled, and could be damaged or come apart if tested prematurely.

Inspect the one-way bearing. The bearing can be rotated one way but not the other, so it is very important it is fitted correctly. Make a note of the flat and stepped sides indicated in the instructions.

Place the one-way bearing, stepped side first, into the hexagonal hole in the back of the recoil starter, press the bearing into place so that it fits neatly and make sure that the knot from the recoil cord does not obstruct the bearing. The bearing should sit fush with its surrounding surface.

Align the recoil starter assembly with the backplate of the crankcase, then gently press the parts together. Make sure the parts are aligned, and that the four screw holes are unobstructed. Then place the first of the 2.5x8mm flange screws into the top right hole and lightly tighten with a screwdriver, followed by the remaining three screws into the other holes, do not overtighten as you may crack the cse of the recoil.

You can now test the recoil cord, though do not pull too hard. The cord should retract into the case when released.
DO NOT overuse the recoil cord, as at this stage there is no lubricating oil inside the cylinder and the friction at this stage could damage the internal parts.

Store the engine unit in a plastic bag until the next stage.
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#5 Posted : 31 January 2014 10:50:08

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Stage 61 - Contains the carburettor and an O-ring.

Place the O-ring over the carburettor spigot. Ensure that the ring is not twisted during placement and is fully seated at the base of the spigot.

Make sure carburettor securing pin, which runs across the carburettor mount on the crankcase, is positioned so that the curved indent upon its shaft is matching the inside curvature of the carburettor mount. This way the carburettor will fit snugly into its mount.

Holding the crankcase assembly in one hand, lower the carburettor into the carburettor mount on the crankcase. Gently slide the carburettor into the mount, twisting it from side to side gently to help it seat on the crankcase.
Once seated snugly, adjust the carburettor so that it sits at a 90 degree angle to the crankshaft and crankcase.

Using the hole marked ‘8’ on the cross wrench, fit over the nut on the carburettor securing pin. Turn the cross wrench until the nut tightens enough so that the wrench stops turning freely, then stop so as not to overtighten it.
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#6 Posted : 31 January 2014 10:56:50

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Stage 62 - Contains the Glow plug and a copper gasket.

Carefully remove the glow plug and gasket from the packaging. Do not touch the filament coil as it is easily damaged.

Carefully place the top of the glow plug into the hole marked ‘8’ on the cross wrench, then place the gasket around the bottom of the glow plug. Making sure that the gasket doesn’t fall off, lower the glow plug into the central hole in the cylinder head. (You might find this easier if you lay the engine on its side or hold it upside down).

Once the glow plug is in perfectly straight, tighten it into place by turning the wrench.

Glow plugs:

Getting the best engine performance from your engine means choosing the right glow plug, which depends on a number of different factors – the engine type, air–fuel mix, fuel nitro percentage, and even the ambient air temperature. What's more, the right glow plug will change as conditions change.
Keeping a range of glow plugs on hand will help you fine–tune glow heat and enjoy maximum performance under all conditions.Generally, hot plugs provide better idle and acceleration than cold plugs. Cold plugs will produce more power but may idle more roughly and be harder to tune. The glow plug provided is an R5.

Glow plug tips:

Use the right glow plug. Tune your engine carefully. Running too lean will make your engine ‘blow’ plugs more often, (proper tuning helps extend plug life). Never touch the filament of a glow plug, even when cold. Don’t over-tighten your plug. Tighten it until it’s just snug.
Be sure to include the glow plug seating gasket. A plug that’s too close to the piston can cause detonation, which will quickly damage a glow plug. Use only a glow starter of 1.5 volts to heat your plug, otherwise, your plug may burn out ahead of its time.
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#7 Posted : 31 January 2014 11:01:20

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Stage 63 - Contains a flywheel wrench, flywheel, tapered colet and pilot shaft.

Take a look at the tapered collet. The top rim is narrow and the bottom wide. To familiarise yoruself with how the tapered collet fits into the flywheel, place the collet, narrow side first, into the hole in the centre of the flywheel, from the side that does not have pins in it.

Once you are familiar with the position of the tapered collet within the flywheel, remove it and slide its wide rim end over the tip of the crankshaft on the engine, and slide the collet along the shaft. The collet should rest against the crankshaft bearing. It does not matter where the split in the collet is situated.

Place the flywheel, flat side first, over the shaft and collet, pushing the flywheel firmly into place. Line up the threaded portion of the pilot shaft with the tip of the crankshaft. Tighten the pilot shaft as far as you can by hand only.

Line up the flywheel wrench with the pilot shaft and the pins in the flywheel. Press the flywheel wrench firmly against the surface of the flywheel. It is important that there is no gap between the wrench and the surface, as this may lead to the pins being bent. Keep holding the flywheel in place, and put the arm of the cross wrench marked ‘10’ over the pilot shaft. Then secure the parts, by turning the flywheel wrench anticlockwise and the cross wrench clockwise. This will push the flywheel further over the tapered collet so that it ‘bites’ and is secured with the pilot shaft.

Make sure there is a gap of around 0.3mm between the flywheel and the crankcase, which is to avoid contact between both parts.
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#8 Posted : 31 January 2014 11:08:53

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Stage 64 - Contains the pre-assembled clutch shoes, clutch neede roller bearing, shim washer, binding head screw and a washer.

DO NOTattempt to disassemble the clutch shoe. The two aluminium alloy shoes are set around the ‘clutch spring’, which is an essential part of the clutch’s operation.

Familiarise yourself with the pre-assembled clutch and identify its front and rear sides.

Line up the clutch to the flywheel, with its rear side facing the crankcase. Insert both of the flywheel’s pins into the two holes in the clutch shoe, making sure they do not get caught on the internal clutch spring.
Now insert the longer tip of the 2mm Allen key into the first hole in the clutch shoe, and push the spring aside to clear the path for the flywheel pin. While keeping the allen key in the hole, with the spring to the outside of the tip, press the clutch shoe down over the shaft. Then reinsert the allen key into the opposite hole, again pushing the spring to the outside of the tip. As you did with the first pin, press down on the clutch shoe.

Place the 5x20mm shim washer over the pilot shaft, (handle this part carefully, as it is very thin and has a sharp edge). Next, place the clutch bearing over the pilot shaft. It does not matter which way round the bearing goes. Then fit the 3x6mm binding-head screw through the 4.5x10mm washer, entering from the un-rounded back of the part. Holding the screw and washer together, place the screw’s tip into the open end of the pilot shaft. Turn the screw by hand into the pilot shaft, only tight enough that it does not fall out, as this is only temporary.
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#9 Posted : 31 January 2014 11:24:58

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Stage 65 - Contains the clutch bell.

You will need to retrieve: The air filter (Stage 3). Silencer assembly (Stage 54). Cable ties (Stage 53). Manifold gasket, 3x10mm cap screws x2, 3x8mm binding-head screws x4 (Stage 53). Shock oil (Stage 9) and chassis.

Familiarise yourself with the clutch bell. The gear at the top is the pinion gear, which transmits the rotational power from the engine to the driveshaft.

Remove the washer and screw temporarily fitted in the previous stage. Place a drop of shock oil onto the clutch needle roller bearing, (do not apply too much as the excess may cause the clutch to slip. You can also use grease).

With the clutch bell aligned with the pliot shaft, push the bell onto the shaft, then replace the washer and screw to secure the clutch bell in place.

This completes the assembly of the GX21 engine.

Mounting the Exhaust, Engine & Air Filter, and making the throttle connection:

Take the silencer assembly and place the two cap screws (Stage 53) into the holes on either side of the manifold base. Both cap screws should be inserted fully. Holding the cap screws in place from beneath, line up the manifold gasket (Stage 53) to the tips of the screws. Then place the manifold gasket over the screws, against the manifold itself. (Ensure that the gasket is correctly oriented upon the manifold so that it corresponds with the shape of the exhaust outlet on the engine when the manifold is offered up to it).

Offer up the manifold to the engine and tighten both cap screws. Tighten each gently first before going on to fasten both fully.

Loosen and remove the screw from the exhaust end of the silencer assembly and keep to one side. Take the chassis and locate the engine onto the four mounting holes in the chassis plate. Holding the engine, turn the chassis over and make sure the four holes are lined up entirely. Then place a 3x8mm binding-head screw (Stage 53) into the first of the holes. Tighten lightly by hand, followed by the remaining three screws.

Turn the assembly back over and line up the engine’s clutch bell to the centre gear cover, so that the teeth of the pinion gear and centre gear mesh correctly. Cut a small length of paper to a width of 1cm and place between the gears. This is to ensure that there is a sufficient gap between the gear teeth. Gently rotate the clutch bell with your fingertip. The paper should be pulled into the centre gear cover with little resistance. Once you are sure the gap is sufficient, stop rotating – the paper should remain fully visible. Holding the engine in place, turn the assembly on its side and tighten one screw, though not fully, then tighten the screw diagonally opposite. Turn the assembly over, then remove the paper, holding the engine straight. Once perfectly aligned, turn the assembly and fully tighten the remaining screws.

Take the silicon tube attached at the bottom of the fuel tank and line it up with the silver fuel inlet nipple at the bottom of the carburettor. Being careful not to damage the tube, push it over the inlet.

Adjust the silencer so that it is not touching the flywheel, then reinsert the screw you removed from the end of the silencer and attach the silencer to the previously fitted stay.

Take the silicon tube from the top of the fuel tank (pressure line), and line up to the nipple on the end of the silencer, carefully push the tip of the tube over the nipple.

When you are happy with the lie of the exhaust system, fit a cable tie around the joint between the manifold end of the silencer and the silicon joint tube and also fit a cable tie upon the manifold if left off previously.

Take the throttle linkage ball end previously fitted on the throttle servo. Line up the ball end with the ball link of the carburettor. Press the ball end onto the ball link together so that the two connect. It is very important that the throttle linkage rod is properly connected.

Take the air filter that you assembled in Stage 3, loosely fasten a cable tie firmly around the pipe, then fit the air filter pipe onto the air intake of the carburettor. Press the pipe firmly over the air intake port then tighten the cable tie and snip off the excess of the tie.

This completes the mechanical assembly of the Chassis.

In the next Stage we will complete the construction of the Hummer H1 by adding the R/C content.

DO NOT attempt to start the engine until after the R/C content has been added.

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#10 Posted : 03 February 2014 09:06:02

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Joined: 24/08/2009
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Hummer R/C installation.

The R/C pack contains the Kyosho KT-3HS Transmitter and KR-3 Receiver.

Installing the Receiver, Battery Box and Switch:

Unscrew the servo horn on both the steering and throttle servos, and the screw holding the lid of the radio box and remove the lid. Then, take the aerial wire from the receiver and pass through the hole next to the throttle servo.

Insert the ends of the servo and power switch cables into the three slots on top of the receiver, then connect the battery box to the power switch. Carefully follow the diagram in the instructions for the placement of the plugs into the receiver.

Insert four AA batteries into the battery box. Ensure that the batteries are in the correct orientation.

Place the receiver and power switch into the slots in the radio box, next to each other. Try to store wires neatly out of the way so they do not become trapped when re-fitting the radio box lid later on.

Now place the battery box into the space in the radio box next to the receiver.

Take the aerial/antenna tube from Stage 45 and insert the aerial wire into it and gently feed through until it emerges at the far end. Then secure the tube into the hole in the radio box from above.

Re-fit the radio box lids and re-connect the servo horns Ensure that you do not trap any of the wires when re-ftting the lids.

Preparing the Transmitter:

Insert the metal aerial into the hole on top of the hand-set and screw into place.

Insert the batteries into the transmitter correctly. Ensure that the batteries are in the correct orientation (+/–) and that they are properly connected.

Switch the power on, and check that the three battery level indicator LEDs come on. If they don’t, check for loose connections or wrongly orientated batteries.

Carefully follow the R/C testing and engine running information provided in the instructions.

To facilitate the starting of the engine, you will need to purchase a 'Glow Starter' as indicated in the instructions.

The Kyosho manual for the KT-3HS system can be found via this PDF link:


Carefully follow the engine start, break-in procedure and maintenance information noted within the instruction manual.

Further information on the GX21 engine can be found via this Kyosho PDF link:


Fuel choice - Choose a nitro fuel with a nitromethane content of 15-25%, though take into consideration that the higher the percentage will also increase engine wear, 16% is adequate.

Fuel health and safety: Always follow fuel manufacturer guidelines. Nitro fuel is toxic by inhalation, when in contact with skin and poisonous if swallowed. Keep fuel containers out of reach of children at all times!
Nitro fuel is highly flammable, so keep the it far away from sources of ignition, even cigarette ash could ignite it. Store within a tightly sealed and secure container, in a well ventilated area and maintain a low temperature.
The methanol content of nitro fuel is ‘hygroscopic’, meaning that it absorbs moisture from the atmosphere, which can lead to corrosion of the internal components within the engine if fuel deposits remain within the enginewhe the model is stored. Therefore you should remove any remaining fuel from the tank and apply an 'after run' oil after each days running, and also avoid leaving the fuel container open for long periods.

Do not run the model without its air filter. Any debris ingress will seriously damage the engine and reduce its life.

Adequate cooling of the engine whilst being run is important, therefore removal of the aforementioend side windows is a must (indicated by the red arrow).

Consider fitting a fuel filter into the fuel line to prevent ingress of debris into the engine via the fuel tank.

Consider fitting a 'failsafe' - A failsafe is a small electronic device that plugs into the throttle channel of your receiver, then your throttle/brake servo plugs into the fail safe. They are usually mounted into the radio box of a car. A correctly set fail safe will return the throttle/brake servo on your car to a position that you have pre-set in the event of the transmitter or receiver batteries being flat, or the car being affected by interference. We advise that this position should be approximately 50% brakes for a nitro car, which will allow the car to come to a controlled stop.

Please take the time to read the safety information provided within the R/C manual.

We hope you have the enjoyed constructing your Hummer H1 and that you have lot's of fun running it!

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