Saito 180 change the Crankshaftpptx

Replacing the Camshaft on a Saito 180. Kevin Kenny : 

Replacing the Camshaft on a Saito 180. Kevin Kenny This PP presentation was done so that the next modeler would not be as intimidated as I was when faced with the task of changing the crank shaft . I had purchased this Saito 180 on E Bay and was very disappointed when I realized that the crank shaft was bent. I went onto the Horizons Hobby site (www.horizonhobby.com) , typed in Saito 180 and when the page popped up on the top right found the complete parts list for this engine. I knew that the carburetor was damaged and that the carburetor manifold needed to be replaced.

Kevin’s workshop : 

Kevin’s workshop

Slide 3: 

I ordered a new Crank case, a complete gasket kit , a carburetor upgrade kit and both the front and rear bearings. The guys at the RC Forum suggested I wait until I get the engine before ordering any parts but I live in Trinidad & Tobago which is a long way from the USA, so I took a chance that I would not order anything that I did not need. An excellent Video is available on changing a crank shaft on a 2 stroke engine on U Tube . Part 1 http://www.youtube.com/watch?v=TuzEco3EDUMbe Part 2 http://www.youtube.com/watch?v=OLSoXPLGzOI

Tools : 

Tools I have a lot of tools but found it useful that the site also identified all the tools needed to disassemble the engine. Note that all tools are metric.

Slide 5: 

I keep a Saito box of parts for each engine I own These were my tools. I had to purchase a puller and a butane torch.

The start : 

The start The first challenge was to get the tapered collet and drive flange off. The video on U tube http://www.youtube.com/watch?v=TuzEco3EDUMbe) dealt with a two stroke engine but the solutions to the problems were the same. The collet is not shown clearly in the parts list so I took this photograph so that you can see why it can be so hard to come off. Because this engine was in a significant crash it was jammed hard on to the shaft and was very difficult to remove.

Slide 7: 

I got a blow torch and heated the collet evenly on all sides, using a glove from our kitchen to hold the hot engine and using the puller, got it to pop right off.

Slide 8: 

It is interesting to note that this is a difficult part to get as it seems to be on back order for months based on comments from individuals on the RC Forum

Front Bearing : 

Front Bearing Part # SAI 120 S20A

Back bearing : 

Back bearing SAI 120S22

Remove the Carburetor : 

Remove the Carburetor Use a 17mm open ended spanner or a crescent wrench Remove the spark plug

Remove the exhaust : 

Remove the exhaust Use a 17mm spanner

Remove the rocker covers : 

Remove the rocker covers Using a 2mm Allen key remove the rocker arm cover bolts Take care when removing the covers not to damage the gasket. If you have not already done so remove the spark plug so that there is no compression in the cylinder head.

Slide 14: 

Using a 2.5mm Allen key remove the rear cover Take care not to damage the gasket

Slide 15: 

Note the top of the cover has an indentation on it. The cover also shows fly wheel marks which are no problem. Damaged gasket

Gaskets : 

Gaskets We suggest that you order the full set of gaskets and a carburetor kit. They are both inexpensive and you are sure to need one of them. SAI 180 91

Mark the piston : 

Mark the piston Once the back is off mark the connecting rod for the piston with an X so that when you are reassembling it will go in the same way it came out.

Pulling off the cylinder head : 

Pulling off the cylinder head Using a 3mm Allen key remove the bolts that hold on the cylinder head There is no sleeve in the cylinder so carefully slide the cylinder off the piston. You may have to turn it to get it off.

Slide 19: 

Be careful as the push rods will fall out if the push rod cover stays with the rocker head Carefully slide out the piston. It will come out easily.

Slide 20: 

Examine the side and the piston ring. This one is in excellent shape. The piston ring Teflon retainer protects the walls of the cylinder head from being scratched. Be careful as they will fall out and easily get lost.

Slide 21: 

Inspect the head of the piston. This one is fine with a small amount of carbon build up. The push rods and the covers can fit either way. I think it is a good idea to leave the rubber seals for the push rod covers in place.

Push the Camshaft out. If it is difficult to get our you may have to heat the housing in an oven or in hot water to get it out. See the U Tube video. : 

Push the Camshaft out. If it is difficult to get our you may have to heat the housing in an oven or in hot water to get it out. See the U Tube video.

Camshaft : 

Camshaft SAI 180 23A This is what it looks like when its new.

Slide 24: 

This is the bent shaft that was replaced. My bearings were good so I left them in. You can rotate them around pushing your finger inside the center. If you feel any side to side movement, hear or feel any grating sound they must be replaced.

Removing the Cam gear : 

Removing the Cam gear Using a 2.5mm Allen key remove the bolts holding the cam housing in place. Hold the cam shaft at Top Dead Center when you are ready to replace the cam housing and set the timing.

Slide 26: 

Cam housing Cam gear

Slide 27: 

There is a mark at the back of the cam gear but I am not sure what it supposed to indicate. Be careful of this gasket however once you ordered the total gasket replacement set it will be included in this package.

Setting the timing : 

Setting the timing Unfortunately there are no marks on the cam shaft that identify the correct tooth to insert the cam gear The cam gear has a timing mark . This should be facing down or in the 6 o'clock position. Use a knife to hold the teeth from moving, hold the cam shaft at Top dead center.

Hold the cam shaft at Top dead center or 12 o’clock position when you place the cam wheel housing back on the crankcase. Be careful not to let it move or the timing will be off. Tighten up the bolts with a 2.5mm Allen key. Remember to tighten alternative bolts to get a balanced fit. : 

Hold the cam shaft at Top dead center or 12 o’clock position when you place the cam wheel housing back on the crankcase. Be careful not to let it move or the timing will be off. Tighten up the bolts with a 2.5mm Allen key. Remember to tighten alternative bolts to get a balanced fit.

The Four Stroke cycle, Saito 180 : 

The Four Stroke cycle, Saito 180 No. 1. TDC, Both Valves are closed, propeller is being turned to the right. This is referred to as the 12 o’clock position. This is the position for the crankshaft when reinstalling the cam gear. This is also the position when you set the tappet clearance on the rocker arm. No.2. Exhaust starts to open, Intake is closed

Slide 31: 

No. 3 Exhaust is fully open, intake is closed No. 4. Intake starts to open Exhaust is starting to close

360 degrees from the start : 

360 degrees from the start No. 5. TDC. Both valves are open, you can blow through the carburetor and air will come out the exhaust No. 6 . Exhaust is closed while the intake is open

Compression stroke : 

Compression stroke No. 7. Intake is fully open while the exhaust is closed No. 8. Both Valves are now closed. This is the start of the compression stroke.

Slide 34: 

TDC , both valves are closed, we are back to the start.

Replace the piston : 

Replace the piston Place the Teflon piston retainers into the piston Put the piston back onto the cam shaft. Make sure the mark on the connecting rod of the piston faces back.

Slide 36: 

Keep the cam shaft in the top dead position while you slide the cylinder head back on the piston. You will have to line up the push rod and push rod covers. Do not worry to much if the push rods do not fit in the rocker arm ends. Bolt down the cylinder head using the 3mm Allen key. Tighten alternative bolts to get a good fit. To get the push rod in the correct position you will have to depress the valve spring.

Slide 37: 

Push rods Push rod covers

New problems with the rocker arm : 

New problems with the rocker arm After the engine had been mounted the entire rocker arm assembly came loose. We unscrewed the pin that holds the rocker arm in place and tightened up the Allen head screw that keeps the assembly tight against the cylinder head Rocker Arm assembly

Slide 39: 

We placed the rocker arm in the assembly with the washer clip facing the center and tightened the pin.

Slide 40: 

If the push rod does not line up in the end of the rocker arm you can use a utility knife or a tweezers to center it in the correct position Using the tools that came with the engine to reset the tappets. To do this the valves must be in the closed position. Use the tappet spanner loosen the lock nut. Place the feeler gauge between the tappet and the rocker arm. The clearance is (.002’-.004”) Take the 2mm allen key and using the feeler gauge move the Allen key so that you can easily remove the feeler gage. Tighten the lock nut. You may have to redo this a few times as in tightening the lock nut the Allen key can move and close the gap.

Replace the rocker arm covers : 

Replace the rocker arm covers If the cover gaskets look damaged replace them from the kit.

You can now move the piston : 

You can now move the piston

Replace the back cover. Make sure the grooved side faces up. : 

Replace the back cover. Make sure the grooved side faces up.

Replacing the carburetor Manifold : 

Replacing the carburetor Manifold When I purchased this engine on E Bay this is the one part I knew I had to replace PART # SAI180 69 Remember when installing the manifold to put a new washer/bushing in the cylinder head intake opening.

Carburetor : 

Carburetor The brass screw is the low speed or idle jet. High speed jet

Adjusting the high speed Valve/jet. : 

Adjusting the high speed Valve/jet. Carburetor upgrade kit with the damaged bushing. We replaced the bushing and reassembled the high speed jet. The busing is pushed into the carburetor housing from the inside not screwed in. The locking nut is screwing from the outside and is tightened to keep it in place. Screw the high speed valve all the way in. Then unscrew 2 full turns. Using a tachometer with the throttle fully open adjust to maximize the RPM. With a 15/8 propeller you should get 10,000 RPM.

Slide 47: 

Carburetor housing Complete Carburetor

Slide 48: 

Intake velocity stack Carburetor gas kit set, SAI180 91

Adjusting the low speed idle needle Jet/valve : 

Adjusting the low speed idle needle Jet/valve Idle needle valve When replacing the idle needle valve make it flush with the outer edge of the throttle lever as shown on the picture on the right. Then turn it one and a half turns in. Adjust to make the engine idle correctly. If there is too much smoke it is too rich, so screw it in a half turn at a time. If it is rich it will also idle very rough. If it stalls when the throttle is opened it is too lean, screw it out a half turn at a time. You will have to reset the high speed valve when you complete adjusting the low speed valve. Throttle barrel housing

Slide 50: 

Throttle lever The bushing is not screwed into the carburetor housing. You can push it out once the lock nut is removed.

Slide 51: 

High speed needle valve Remember to replace the spring for the throttle barrel. The smaller end of the spring goes in first.

Slide 52: 

Carburetor manifold SAI 180 69 Carburetor upgrade kit PART # SAI 450 R3D 84A

Ready to go Flying? : 

Ready to go Flying?

Then, Go flying now! : 

Then, Go flying now!

Best regards from Trinidad & Tobago : 

Best regards from Trinidad & Tobago