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 Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 65 - Contains the engine crankshaft.
The crankshaft is a key component of your model RB7’s GX21 engine, and you insert it into the crankcase through the two pre-fitted ball bearings.
As the crankshaft won’t be used until the engine is complete, protect it from corrosion by applying a coat of 'after run' oil. You can get this oil from your local model shop, or an online supplier.
Hold the crankshaft by the pin on the ounterweight, as shown, and apply a few drops of after run oil. Turn and tilt the shaft (and use a fingertip, if necessary) to spread a thin film of oil over the entire surface.
Hold the shaft by the counterweight and, keeping it horizontal, insert it into the bearing at the rear of the crankcase. Gently push it through until its threaded end protrudes from the bearing at the front.
When the tip of the crankshaft protrudes through the front bearing of the crankcase, grasp it with your fingers and pull it through as far as it will go. When you do this, make sure that the shaft remains perfectly level within the crankcase housing so that it sits correctly within the bearings.
Adjust the crankshaft so that its counterweight is positioned exactly as it is in the instructions photo. The counterweight should sit directly next to the rear bearing and be clear of the milled ring on the inside of the crankcase.
Store your engine assembly within a sealed bag until the next session, when you will fit the cylinder and piston.Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 66 - Contains the piston and cylinder liner.
Slide the piston out of the bottom of the cylinder liner.
Looking into the crankcase from the rear, rotate the crankshaft by hand until the counterweight is at the top and the crankpin is at the bottom.
Note the orientation of the piston as shown in Step 2 of the instructions, then lower the piston into the top of the crankcase.
When the piston is in place, fit the piston conrod end over the crankpin on the crankshaft counterweight. Use a finger to push the big end onto the crankpin, until it clicks into place. Check that the big end is fully in place on the crank pin.
Turn the tip of the shaft to bring the piston down to its lowest position, then slide the cylinder liner into the opening in the top of the crankcase, with the largest rectangular hole in the liner facing the exhaust port at the rear of the crankcase.
Lower the cylinder liner very gently into the hole, until it comes to rest on the top of the piston. Do not use too much force to do this, as you may damage the parts.
Turn the crankshaft slightly in each direction to help the cylinder liner fit over the piston, then carefully push the liner fully into place within the crankcase.
When the cylinder liner is fully inside the crankcase, look through the exhaust port and adjust the liner so that the large rectangular hole is fully lined up with the opening of the exhaust port.
Store the engine assembly within a sealed bag until the next sessionTomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 67 - Contains the cylinder head, head gaskets, cap screws and a 2mm allen key.
Before you begin the assembly work, double-check that the cylinder liner is correctly positioned within the crankcase (see Step 15, Stage 66). Correct alignment of the liner is essential for the engine to work properly.
Place the two gaskets on top of each other on the upper rim of the cylinder liner, make sure you position them precisely.
Very carefully lower the cylinder head onto the top of the crankcase, so that the screw holes line up and the front edge of the head is level with the rear of the carburettor mounting. Be very careful not to displace the gaskets when you do this.
Carefully hold the cylinder head in place on the crankcase, and one by one drop the six cap screws into the six holes in the top of the head. Holding the 2mm allen key by its shorter arm, insert its longer arm into each hole and tighten the six screws, secure the the head evenly, tighten the six screws in the order shown.
This stage is now complete. Store the engine assembly within a sealed bag until the next session, where we will assemble and fit the engine backplate.Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 68 - Contains the rear engine plate and recoil starter shaft.
Insert the recoil starter shaft into the bearing in the rear plate as shown, and push it in until the circular flange at its end is flat against the raised section of the plate.
Place the gasket over the raised cylindrical section of the rear plate and adjust the gasket so that the four small holes in it align with those on the rear plate.
Place the engine upright on your work surface with its back towards you. Now place the rear plate against the open end of the crankcase, with its triangular projection on the left and its four screw holes lining up with those on the crankcase.
Turn the starter shaft until the notch on the flange engages fully with the crankpin. Then press the rear plate snugly up against the crankcase. Make sure that the gasket stays in place when fitting the notch in the starter shaft flange over the crankpin on the crankshaft.
Make absolutely sure that the rear plate is sitting tight against the crankcase, with no gaps in the joint. When you are sure that the rear plate is sitting perfectly flush with the crankcase, insert the four cap screws supplied with this stage and screw them in loosely by hand. When you have tightened all the screws by a few turns each, use the 2mm Allen key to tighten each one fully to fix the rear plate to the crankcase.
Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 69 - Contains the recoil starter, 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 come apart if tested prematurely.
An arrow stamped on the front face of the bearing, indicated in this photo by a red arrow, shows the direction in which the bearing turns when the starter cord is pulled. This is the side that will face the engine.
Hold the recoil starter with the open side towards you, and place the one-way bearing, with its front facing towards you, into the hexagonal recess. (The front of the bearing is the one stamped with an arrow). Push the one-way bearing into the recess until its edges are level with the sides.
Put the starter up against the rear plate, with the starter’splastic housing at the base of the handle aligned with the triangular projection on the plate, then insert the four flanged screws supplied with this stage through the holes, and tighten each with a Phillips screwdriver. Be careful not to overtighten as you may crack the plastic housing of the starter..
This stage is now complete. As before, store the assembly in a sealed plastic bag until next time, to prevent dust from getting inside it.
Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 70 - Contains the carburettor and its O-ring.
Place the rubber O-ring over the lower spigot of the carburettor. Push the O-ring right up against the main body of the carburettor, so that there is no gap between the two.
Take the engine assembly and loosen the nut on the carburettor attaching screw arrow. Then turn the screw so that the cut-out in its shaft matches the contour of the inside edge of the carburettor mount, ready for the carburettor to be fitted.
Line up the carburettor with its mount and carefully fit the two together. Push the carburettor firmly into the mount until the rubber O-ring sits firmly against the mount’s rim.
There should be no gap between the O-ring and the rim. Using the longer end of the crosswrench, fully tighten the nut on the carburettor attaching screw.
The carburettor is now fastened securely in place.Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 71 - Contains a glowplug and copper sealing gasket.
Carefully remove the glow plug and gasket from the packaging. Do not touch the filament coil as it is easily damaged.
Place the copper gasket onto the bottom of the threaded end of the glow plug.
The glow plug and gasket are fitted into the central hole in the top of the cylinder head.
Hold the threaded end of the glow plug and insert the other end into the arm of the cross wrench marked ‘8’, lower the 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). Carefully tighten it into place by turning the wrench clockwise, taking care not to cross-thread.
When viewed from above, the glow plug should be centred in the hole and sitting perfectly straight, with its copper gasket forming a seal between it and the cylinder head.
Store your engine in a sealed plastic bag until the next time you work on it.
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.
Tomick attached the following image(s):
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Rank: Pro Groups: Joined: 24/08/2009 Posts: 48,051 Points: -13,308
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Issue 72 - Contains the right rear tyre, wheel and rim decals.
Assemble the tyre and decals onto the wheel as before.
Remove the flange nuts from both the rear wheel shafts by turning them anticlockwise, (take care that the hex pin does not fall out).
Fit the right rear wheel from this stage and then fit left rear wheel assembled at Stage 53, using the crosswrench (marked 10) to secure the flange nuts.
Tomick attached the following image(s):
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