From GICLWiki

Saturday May 25 2013 02:06

Introduction

This is the critical design review for Group 36. This gate is for the reassembly processed used for the engine and transmission. The reassembly process is a step-by-step process to put the components of the product back together as well as make comparisons to the dissection part of the project.

Directory

Home: Group 36 Home Page

Gate 1: Request for Proposal

Gate 2: Preliminary Project Review

Gate 3: Coordination Review

Product Reassembly

Note: All images are the same as the ones presented in assembly and analysis.

As in the dis-assembly process, socket wrenches were used for the majority of the procedure. They will be referred to as wrenches unless otherwise noted in the tools section of each step.

Difficulty scale is from 1-5 where 1 is a simple step and 5 is a difficult step.

Step 1: Inner Left Transmission Housing

Tools: 8 mm wrench

Fasteners:

Figure: Split Transmission Case

2x 8 mm hexagonal washer bolt of length 60 mm
1x 8 mm hexagonal washer bolt of length 48 mm
2x 8 mm hexagonal washer bolt of length 64 mm

Difficulty: 2 This step can be somewhat difficult because some of the shafts require some effort to get into the correct position. Other than that it is straight forward.

a. Slide the inner left transmission housing onto the inner right transmission housing. All the shafts must line up and go through their respective holes in the housing. The idea is simple, but it might take some time to get it back on. It is recommended that two people do this step. One can adjust the shafts to make the sure they are going into their slots while the other people applies pressure to the two parts so that they come together.

b. Once together put the six washer bolts back into their respective holes. It does matter which ones go where because some of the bolt slots are deeper than others. Just make sure that when they are being put back that the bolt reaches the threaded part of the hole and that there is no excess bolt hanging out of the hole.

Step 2: Piston Head

Figure: Piston Head

Tools: flat head screw driver

Figure: Crankshaft

Fasteners: N/A

Difficulty: 2 The steps are not particularly difficult, but there is a chance to lose parts. It can also get difficult to line all the parts up without assistance.

a. There is a shaft that runs through the piston head. There are two rings that keep the shaft from just sliding out of the piston head. These rings are located at either end of the shaft. Use a flat head screw driver to press down and out on the ring to pry it out. Note: You will need to use a significant amount of force to do this and therefore the ring will most likely shoot out of the piston head. Be sure to block the ring from flying off so that you do not lose it. Eye protection may also be a good idea.

b. Once the ring is removed slide the shaft out. Line the shaft slots on the piston head up with the hole on the connecting rod. Slide the rod through the lined up holes and then force the ring back into place. Again this will be much easier to do with assistance as one person can line up the holes while the other slides the shaft in.

Step 3: Cylinder Housing

Tools: 10 mm wrench

Fasteners:

Figure: Piston Housing

1x hexagonal full thread washer bolt with Phillips slot

Difficulty: 2 The only part that adds difficult part to attaching this section is to compress the rings around the piston head so that is can fit into the cylinder.

a. Take the black cylinder housing component and slide it down the four copper colored rods that are surrounding the piston head. The cylinder protruding from the housing slides down first and fits into the transmission housing. Also make sure the rectangular slot is on the left side of the housing. There are rings around the piston head that must be compressed so that it can fit into the cylinder. A two person system where one person compresses the rings while another pushes the cylinder housing is recommended. Note: Putting oil on the inside of the cylinder is recommended so that when the rings on the piston head expand to fill the cylinder they don’t scratch and damage it.

b. There is a threaded hole on the housing that lines up with a threaded hole in the transmission housing. Put the bolt mentioned in the fasteners section into this slot and tighten.

Step 4: Tensioner Assembly

Tools: 17 mm wrench

Fastener:

Figure: Tensioner

1x 17 mm black bolt
1x 7 mm full thread washer bolt
1x 17 mm silver washer bolt

Difficulty: 4 There are a lot of parts involved in this step of reassembly one of which is a spring that can make this difficult. It is highly recommended to do this part of the assembly with another person.

a. First make sure all the parts for the assembly are on hand. There should be an armature with rubber gear attached, a rubber pulley, the timing chain, a tensioner rod, and a spring with tapered diameter at one end. This assembly is going to be placed in the circular “window” in the inner left transmission housing.

b. Position the black bolt through the hole in the armature. Screw the bolt into the bolt slot in the up right side of the “window” so that the gear is on the left (above the gear that was attached to the transmission housing) and the rounded metal end of the armature is to the right.

c. There is a bolt slot on the underside of the transmission housing that feeds all the way into the area where the tensioner assembly is going to be. Put the tensioner rod into this slot so that the rubber end of the rod will end up inside the assembly area and the metal end will be inside the slot. Take the spring and put in the slot so that the tapered end is in contact with the tensioner rod. Compress the spring with the silver bolt and then screw the bolt into the slot. If done correctly the rubber part of the tensioner rod should be in contact with the armature.

d. Take the chain and loop it around the crank shaft. There is a gear on the shaft that the chain meshes with. Feed the chain through the slot on the cylinder housing. The chain should also be able to mesh with the other two gears, the one attached to the armature and the one attached to the transmission housing.

e. There is a threaded slot on the cylinder housing that goes into the rectangular slot. The pullet goes into the rectangular slot and the 7 mm bolt goes through the threaded slot and holds the pulley in place. Get pulley inside the chain loop and meshed with the chain then bolt the pulley into place.

Step 5: Head gasket

Tools: N/A

Fasteners:

2x 7 mm sleeve of length 14 mm
2x 7 mm sleeve of length 12 mm
1x flanged sleeve
1x 19 mm rubber spacer
1x 17 mm rubber spacer
1x 26 mm washer
1x 15 mm washer

Difficulty: 1 This only requires sliding parts down the copper colored rods.

a. First slide the head gasket on so that the all the holes on the gasket line up with the holes on the cylinder housing. There is a rectangular hole that should line up with the timing chain slot and a larger circular hole at the bottom of the housing that lines up with a hole in the gasket.

b. Position yourself so that you are looking directly at the front of the engine (You should be able to see the piston head). The top two rods each have one 12 mm sleeves and the bottom two rods each have a 14 mm sleeve. The flanged sleeve goes in the bottom hole.

c. The 15 mm washer goes around the bottom left rod.

d. The 19 mm rubber spacer goes around the top left rod.

e. The 17 mm rubber spacer goes to the top right rod.

f. The 26 mm washer goes to the bottom hole. However it must be held in place until the valve assembly is put over it to hold it in place.

Step 6: Valve Assembly

Tools: 8, 9, 10, and 17 mm wrenches

Figure :Valves

Fasteners:

2x 9 mm nuts
4x hexagonal flanged cap nuts
4x 8 mm washers
2x 8 mm hexagonal full thread tap bolts of length 20 mm
1x 10 mm hexagonal full thread tap bolts of length 110 mm
1x 6 mm washer
1x 10 mm hexagonal full thread washer bolt with Phillips slot
3x 8 mm hexagonal full thread bolts

Difficulty: 3 This is a straight forward step that for the most part only requires making sure that bolts are being used in the right spots. The difficult part is getting the timing chain around the sprocket.

a. Slide the valve assembly onto the four rods. Make sure the threaded hole is lined up with the threaded hole on the cylinder housing. Screw the bolt with the Phillips slot into this hole.

b. Attaching the timing sprocket could require two people. First get the sprocket threaded with the chain. Then line up the three holes on the sprocket with the three holes on the valve assembly. Use the 8 mm bolts to screw it in place. Note: The holes are not evenly spaced around the center of the sprocket. This means that there is a specific way to get the holes to line up. One person should hold the sprocket while the other rotates the plate on the valve assembly until all the holes line up.

c. Screw the 9 mm nuts onto the valve stems. Screw the valve covers over the valve stems.

d. Slide the octagon shaped cover onto the copper colored rods. Screw a capped nut onto each of the rods.

e. Screw the rectangular plate to the left side (when viewing the engine from the front) with two 8 mm bolts. The center hole is for the 110 mm bolt and goes through the whole assembly. Hold the circular cover to the right side of the engine (covering the timing sprocket) and slide the bolt through. It tightens into the circular cover.

f. Screw in the spark plug on the right side of the valve assembly. The slot is set deep into the housing.

Step 7: Drive Chain Gear

Tools: 10 mm wrench

Fasteners:

2x 10 mm hexagonal full thread bolts bolt
1 sprocket spacer

Difficulty: 2 The spacer needs to be lined up with the bolt slots on the sprocket.

a. Slide the sprocket onto the drive shaft. The inner teeth should lock it in place.

b. Slide the spacer on. The teeth force it to slide on in a set way, but there is a slot on the shaft where there are no teeth. Use this space to rotate the spacer until the holes line up with those on the sprocket.

c. Screw the 10 mm bolts in to fasten it in place.

Step 8: Magneto Stator Plate

Figure: Stator Plate

Tools: #4 Phillips head screwdriver

Fasteners:

2x flat head Phillips bolts

Difficulty: 1

a. The stator plate fits into the “window” mentioned earlier. Line up the holes and make sure the two arms of the stator plate are at the bottom right side.

b. Screw in the flat head bolts.

Comparison: This step was much more difficult in dis-assembly because the bolts were very tight. Phillips head screws tend to slip which made it difficult to get the bolts out because they kept stripping.

Step 9: Stator Plate Wiring

Tools: #2 Phillips head screwdriver

Fasteners:

4x round Phillips head bolt

Difficulty: 4

a. Screw the wire coil into the top and right prongs on the stator plate. Make sure it isn’t screw in backwards. The metal sections on the wire coil that get screwed to the plate have a rounded edge. This rounded edge should be facing outwards.

Figure: Stator

b. The black plastic part of the wiring with the metal nub slides into the two arms on the stator plate. The nub should be pointing toward the center of the plate. Screw it into the arms with two bolts.

c. There is a rubber part holding the wires together that has two flanges. There is a notch in the transmission housing where this rubber part fits into. The wires with plastic part at the end should be coming out of the transmission housing.

d. The wires have metal brackets at two locations. These brackets need to be spot welded back into place. The metal bracket closer to the rubber section has a hole on it that must be pressed over a metal bulb near the top of the transmission housing. Weld it in place after.

e. The second metal bracket is just welded into place between the two arms of the stator plate. Note: For the groups reassembly a spot welder was not available. The part still needed to be grounded so it was screwed to one of the arms with the black plastic part.

Comparison: This part was more difficult than the disassembly because it required the brackets to be spot welded. It also requires more precision in getting all the wiring together. Prying the brackets off and pulling all the wiring out is a much simpler task.

Step 10: Magneto

Tools: 17 mm wrench

Fasteners:

Figure: Magneto

17 mm washer nut

Difficulty: 2 The nut must be tightened a lot.

a. Slide the magneto onto the crank shaft. Make sure no wires are interfering with the rotation of the magneto. Put the nut on and tighten. Either clamp down on or have someone hold the clutch to keep it from rotating.

Step 11: Shifting mechanism

Figure: Shifting Attachment

Figure:Clutch

Tools: N/A

Fasteners: N/A

Difficulty: 1

a. Attach the select lever to the flanged shaft on the magneto side of the transmission. It should be parallel

b. The arm slides onto the same flanged shaft on the other side of the transmission. The cylindrical protrusion faces towards the clutch and should be over the clutch.

c. The round part of the mechanism slides into the center of the clutch so that the mandibles straddle the cylindrical section of the arm.

d. The spring fits inside the sleeve which then fit into the center of the round section (put it in spring first).

Step 12: Outer Right Transmission Housing (clutch cover)

Tools: 10 mm wrench

Fasteners:

1x 10 mm hexagonal washer bolt of length 80 mm
2x 10 mm hexagonal washer bolts of length 64 mm
5x 10 mm hexagonal washer bolts of length 40 mm

Difficulty: 3 The bolts belong to certain slots depending on size. The shifting mechanism underneath the housing makes it difficult to slide on because it needs to be lined up properly.

a. Inside the section of the clutch cover that will be covering the clutch there is a rotating part with three arms. These arms fit inside the “waves” in the round part of the shifting mechanism. When the housing is being put on have some pushing the select lever while the cover is being pushed in. This will allow the waves to line up with the three armed part on the cover.

b. Screw in the bolts in the same fashion as they were in step 1 (fitting bolts into the correct sized slots).

Step 13: Outer Right Transmission Housing (magneto cover)

Tools: 10 mm wrench

Fasteners:

1x 10 mm hexagonal washer bolt of length 28 mm
1x 10 mm hexagonal washer bolt of length 35 mm

Difficulty: 1

a. There are only two bolts to be screwed in. The longer bolt goes to the longer slot and the shorter bolt goes to the shorter slot.

Step 14: Oil Drain Bolt

Tools: 17 mm wrench

Fasteners: (this is a fastener)

Difficulty: 1

a. Flip the engine over. There should be a slot for a bolt still open. Screw in and tighten the bolt.

Step 15: Kick Start

Tools: 10 mm wrench

Fasteners:

1x 10 mm hexagonal full threaded tap bolt

Difficulty: 1

a. Attach the kick start lever to the splined shaft that is still visible. Make sure the foot rest for the lever folds out and away from the bike. The lever should also be facing towards the rear of the bike. The angle of attachment can be whatever is most comfortable to the rider.

Step 16: Plastic oil Plug

Tools: N/A

Fasteners: N/A

Difficulty 1

a. Screw in the plug to the slot by the kick start lever.

Discussion

The product was not tested to see if it would run (do to time and monetary constraints.)

The group was unable to get the wiring back to the exact way it was before dis-assembly.

Wires attached to the ignition coil where soldered and riveted to the motor as a means of grounding the electrical system. Both were accidentally broken away from their soldered position during dis-assembly. During re-assembly, one contact was re-attached to its rivet. Albeit, it was not re-soldered and the contact could work itself free if the bike was used regularly again. Re-soldering it would remedy this. The second contact was re-attached by placing the hole in the contact at a point on the frame where a screw held part of the electrical system to the frame. This is metal, and should do well acting as a ground. Ideally, the contact would be soldered back to its original position.

These contact points would most likely be the source of any problem with the engine. If they fail the spark plug will not fire and there will be no detonation and the motor will stop working.

We were able to put all the other components of the engine together the way it was originally was. However, our group was only responsible for the engine and cannot be certain whether other components of the bike outside the engine would cause the dirt bike to not run properly, or not run at all. This refers, specifically, to the line running from the throttle to the carburetor, the throttle itself, suspension, brakes, and their associated components.

The engine needs oil, as it is totally empty. Without this, the engine will be totally destroyed if any attempt is made to make it run. Other than this, the motor should run.

The reassembly process was easier because we understood where everything went (minus a few instances.)

We forgot to re-attach part of the system that allows the motors gears to be changed. This was discovered after the entire motor was back together. Fortunately it was relatively easy to remedy.

Placing the seals in between each part of the transmission casing proved to be fairly difficult at first. We eventually used a small amount of oil and rubbed it along the boundary, which caused the seal to stick while we bolted it together.

The same tools were used for both assembly and dis-assembly. Had the group decided to pull off the gears of the transmission a tool would have been necessary to re-press them on. This would be one of the only changes in tools necessary. Also, though the same tools were used not all were used in the same way. The flat head screwdriver, which was used for prying the transmission housings apart was not needed for that purpose for reassembly.

It is difficult to offer any improvements to this device, as it seems that we do not have the technical expertise or knowledge to improve it.

Group 36 Reassembly

Contents