Gate 4: Explanation

Product Management

Cause for Corrective Action

This portion of the project proved especially difficult to complete, as our group had a limited amount of time to assemble the engine. This issue was compounded by the fact that we have reached the end of the semester and all members of our group had additional obligations to balance with the engine project. To ensure the assembly was completed on time, both groups spent the better part of the last two labs sessions putting all the parts together, just as it was originally given to us. In the end we were able to complete the reassembly on time and move on to the gate submission which was completed over the course of the entire weekend. While completing such a large amount of work in one solid run was tough, everyone focused and completed their respective parts to complete the gate.

Product Archaeology

Product Reassembly

Original Assembly

During the reassembly process we utilized a manual for the engine which guided us through the necessary steps. For this reason, our assembly process does not differ from the original process which was followed during the engine's manufacture, except for the times when external covers were secured. The only other difference is in the tools that we used. In a factory setting, all fastening would have been done with power tools instead of flat wrenches and screw drivers.

Difficulty Scale

Our difficulty scale is based upon a few key factors, such as the tools used, the amount of forced needed to attach the part, and also the number of group members needed in each step. Our scale was quantified into simple scale from 1 to 5, 1 being the simplest and 5 being the most difficult. The following synopsis gives a description of each level of difficulty.

1- Part is easily reassembled and secured by hand with minimal force

2- Part requires simple tool with minimal force, or significant force by hand

3- Part requires simple tools and significant force

4- Part requires specific tools and significant force

5- Part requires specific tools, multiple individuals and significant force

Note: "None" under the "differences" column of the chart implies that part assembly was simply the reverse of the disassembly process. It should also be known that parts that were not connected in some way were not necessarily reassembled in the same order as they were taken apart in, so long as their assembly did inhibit other parts.

Step Description	Difference from assembly	Assembly	Difficulty	Picture
1. Fasten oil pan to lower crankcase	None	10 mm wrench, 14 bolts	2
2. Slip shifter drum into lower crankcase	None	Press in with hands	1
3. Slide bearing over shifter drum shaft	None	Hammer in with rubber mallet	2
4. Attach oil pump with two 10mm bolts	None	10 mm socket wrench	2
5. Attach small metal plates to hold in shift drum bearing	None	8 mm socket	2
6. Assembled shift forks and shift fork shafts into gear housing	During reassembly we had to take care to replace the forks in the same places and orientations as before.	Slide on with hands	3
7. Attach shift fork fasteners	None	10 mm socket wrench	2
8. Attach gear shift spindle in place	None	Insert by hand	1
9. Put shifter cam on shifter drum bearing and shifter cam center bolt	None	Slide on by hand	1
10. Place stopper arm washer, spring, arm bolt holding	None	Flathead screwdriver, 10 mm socket wrench	3
11.Carefully assembled counter and main gear shaft, resting on shift forks	During disassembly we simply lifted the shafts out whereas in reassembly we had to carefully align the forks otherwise the shafts would not set into place.	Rubber mallet	4
12. Assemble clutch	Cluth assembly was more difficult because each plate needed to be carefully lined up.	Assemble by hand	2
13. Assemble oil pump drive, fasten to lower crank case.	The oil pump was inclined to fall apart so it had to be carefully held in place before it was fastened shut.	10 mm socket wrench, 3 bolts	2
14. Attach oil pump sprocket bolt to oil pump	Reassembly took two people as opposed to one for dissection.	10 mm socket wrench	4
15. Place clutch outer on main gear shaft	During reassembly we had to take note that the main bearing could not be placed on before the outer clutch.	Place on by hand	1
16.Insert clutch main bearing main shaft	None	Slide in by hand	1
17. Insert clutch center lock nut on main shaft	None	Slide on by hand	1
18. Insert pistons into upper crankcase and connecting rods	None	Push in by hand	2
19. Secure connecting rods onto crankshaft	In order to complete this step we had to flip the upper crankcase over and take care that the pistons did not fall out.	10 mm socket wrench	3
20. Fasten bolts that connect upper and lower crankcase	None	10 mm socket wrench	2
21. Fasten crank case cover to crankcase	None	10 mm socket wrench, 8 bolts	2
22. Push timing sprocket onto crankshaft	None	Push on by hand	1
23. Lower cylinder head onto upper crank case	None	Place on by hand	2
24. Connect cylinder head to engine block	None	Allen wrench	5
25. Fasten cylinder head to crankcase	None	10 mm socket wrench	2
26. Attach cam chain to crankshaft sprocket	Attaching the chain was as difficult as it was to remove.	Place on by hand	4
27. Attach timing chain crankshaft cover	None	10 mm socket wrench	3
28. Attach cam chain tightener to top engine block	Replacing the tightener was more difficult than removing it.	10 mm socket wrench	4
29. Attach cam shaft cover	None	10 mm socket wrench, 2 bolts	2
30. Fasten valve cover to cylinder head	None	10 mm socket wrench	2
31. Attach starter motor to lower crank case	None	Press in by hand	1
32. Attach springs/caps to carburetors	None.	Place springs in with hand, philips head screwdriver	1
33. Attach 4 carburetors together	In separating the carburetors we pried them apart with a screwdriver and in reassembling we hammered them with a rubber mallet.	Rubber mallet	3
34. Attach air filter to base of air box	None	Philips head screwdriver, 6 screws	2	thumb
35. Attach air box cover to assembly	None	Philips head screwdriver, 7 screws	2
36. Connect carburetors to air box	None	Press in by hand	1
37. Attach spark plugs	None	Screw in with hand	2
38. Attach and fasten camshaft covers	None	10 mm socket wrench, 10 bolts each	2
39. Place thermostat into housing	None	Place in housing with hand	1
40. Fasten outer water cooling pipe to housing	None	8 mm socket wrench	2
41. Fasten starter motor to lower crankcase	None	8 mm socket wrench	2
42. Attach alternator to lower crankcase	None	8 mm socket wrench	2
43. Attach coolant pipe to upper crankcase	None	10 mm socket wrench	2
47. Attach air-box assembly to cylinder head and tighten screws.	It was substantially easier to remove this component because assembly was inclined to fall off.	Press on by hand and small philips head screwdriver.	2

Design Revisions

Fuel Injection

Fuel injector design

Fuel injector functional image

The first change would be to replace the carburetors with fuel injection. Instead of relying on small openings and pressure zones to mix the fuel and air, the injection system would atomize the fuel and “spray” in exact portions into the piston chamber using a computerized system. This would increase the cost of the engine but improve its performance, efficiency and reliability.

Advantages:

More complete fuel burn: A fuel injection system atomized the fuel as it injects it into the expansion chamber. This allows the fuel to more completely and efficiently burn. A fuel injection system allows for a more precise release of the gasoline into the chamber, and thus allows the engine to run a leaner mixture. using a leaner mixture means that less fuel is needed to run the engine while still producing the same amount of power. The increased efficiency would address both economic and environmental factors, as the engine would pollute less, and get better gas mileage which would lessen the amount of money the end user must spend on fuel.

Better throttle response: Fuel injected engines benefit from a more immediate throttle response than a carburated engine. The fuel injected engine would more readily and immediately respond to the users commands than a carburated engine. this addresses the societal factor of usability and product feel, as the user would feel a noticeable difference in response from the engine. This impacts societal conciderations because it affects the response of the bike to the user.

Easier starting: There is no choke in a fuel injected engine and they are nearly impossible to flood. A fuel injected engine would also be be much easier to start in all weather conditions than a carbeurated engine which inpacts the engine societal factors of the bike because it increases the user friendlines of the engine. This also related to overall better operation over a wider temperature range which impacts the engine design globally because the engine can work in a greater range of climates and geographic areas.

Disadvantages:

Ease of service: The downside to a computer controlled machine is that a breakdown can no longer be fixed with simple tools, and the ability to “tinker” with the bike is decreased. Carburators are much simpler than fuel injection systems and can be easily adjusted by an owner with a service manual.(economical because of repair costs)

Higher initial cost: A fuel injection system would be more expensive to include on an engine than carburetors. The advanced technology is built to stricter tolerances and uses computerized components that are more complex to make and require more manufacturing processes and more in depth development.

Five Valves per Cylinder

Adding an additional intake valve to each cylinder of the engine.

5 valve engine top

detailed view of 5 valve system

Advantages:

More Power: An additional intake valve would allow for additional fuel to be relseased into the expansion chamber, and would increase the amount of turbulence in the chamber, which increases the dispersion of the fuel. The additional fuel would provide the engine with additional cranking power. This advantage addresses the societal factor of the user experience. The additional power would be noticed by a rider and would make the bike more desirable than a similar four valve per cylinder engined bike.

Higher Max RPM: As each valve would be smaller than in a similar sized four valve engine the valves would be able to open and close more easily and would not be as susceptible to valve float and other limiting factors to high engine speeds that engines with fewer valves per cylinder are susceptible to. A higher maximum RPM would address the societal factor of user feel, as the end user would have a wider range of usable engine speeds which would be usable.

Disadvantages:

Cost: Additional manufacturing processes would need to be added to incorporate an additional valve to each cylinder, and additional parts would need to be machined, such as the extra valve and the port which it would be inserted into. This is an economic factor, as the engine would probably cost more initially for the end user.

Added Complexity: An additional valve in each cylinder could also be looked at as an additional component to fail in an engine, and would make repairs more expensive if something were to go wrong in the engine. Adding another level of complexity also increases the cost of rebuilding the engine, as replacing valves would cost more because of the additional parts. This addresses both the societal factor of serviceability and the economic factor of increased service cost, although service would not be needed as often as a similarly set up carburated engine.

Addition of Catalytic Converter

In its present state the engine does not have a catalytic converter, and exhaust gasses are released into the atmosphere untreated, full of noxious, polluting chemicals. Adding a catalytic converter would greatly reduce the negative emissions released by the bike.

Basic Catalytic converter

Detailed view of a Catalytic converter

Advantage:

Lower Emissions: Catalytic converters drastically reduce hydrocarbon, carbon monoxide and nitrous oxide emissions. Each of these is a pollutant that negatively impacts the environment. This addresses environmental factors, as the lowered emissions of the engine due to the catalytic converter would make the engine much more environmentally friendly.

Disadvantages:

Cost: Adding a catalytic converter would be an additional component on the engine, and would add additional manufacturing processes to its assembly. While it would be a one time investment, this cost would be transferred to the user, and would be considered as an additonal economic factor for this engine.