Group 13 - Gate 4: Product Archaeology
Reassembly Difficulty Scale
During the reassembly there were various steps that required different amounts of work, effort and tools. The difficulty of each step was broken down into three different levels based on a criteria created by Group 13. The different levels of difficulty are described below:
|Team Members Required||Tools Required||Effort Required||Number of Fasteners Used||Number of Components||Number of Subsystems Involved|
|Scale Criteria||This part of the scale was graded based on the number of team members needed for the step. One point was given for each member that was needed during the process.||In this step one point was given for each tool that was used. There was no cap on the amount of points given during this step. (Note: A socket and its drive counted as to points, considering one drive was used with multiple sockets in some cases.)||The effort scale was based on three different categories of effort, the first being minimal which meant the persons performing the job put no effort in, parts could be connected and assembled with no strength or force needed. The second was moderate effort, meaning that effort was needed but the job only gave moderate resistance and required effort, but nothing strenuous for the team member. The final score for the effort, was maximum, which meant that the step required an extreme amount of force, and parts that were very resistant to fastening. Fasteners required larger amounts of torque and parts were heavy and difficult to align and reassemble. One to three points were awarded for this scale, one, two and three points given respectively for the different amount of effort.||In this step one point was awarded for each piece of hardware used in the reassembly, there was no cap to the amount of points a step could accumulate.||This section of the criteria, points were given for the amount of components that were involved in the reassembly. The points were given for the number of components that were involved in the mating of the two involved parts during the reassembly.||The last part of the criteria gave points to the number of subsystems that were involved in the step being evaluated by the criteria.|
- Table-A: The above rubric is for the evaluation of the difficulty of each step completed during the reassembly of the Honda Engine. The larger the amount of points that a step scores based on the criteria the more complex the step was. It contains the possible points that each step could score and the description of how and why the points were given to each step.
In the following documentation of the reassembly, the aforementioned difficulty criteria were applied to describe the complexity of each step.
The reassembly was performed in the lab, located in Furnas Hall, during the allotted office hours. It was performed by a combined effort of Team 13 and Team 23. The following is an account of the assembly completed by Team 13:
The first step of the reassembly was to put the various transmission components back in the casing.
The second step of the reassembly was to put the clutch back together in proper operating order.
The following step reassembled all of the clutch components together.
The following step of the reassembly involved seating the crankshaft in the crankcase.
The following step of the reassembly involved putting the pistons back in the crankcase.
The following step of the reassembly involved securing the connecting rods to the crankshaft.
The following step of the reassembly connecting the two halves of the crankcase together.
The head gasket then needed to be placed in its proper location on top of the head.
The following step of the reassembly involved the starter being connected to the crankcase.
The following step of the reassembly involves securing the clutch cover onto the crankcase, to finish the clutch assembly.
The following step of the reassembly involves attaching the alternator to the crankcase, as well as the its cover.
The following step reseated the camshafts within the head.
The following step of the reassembly secured the camshaft covers onto the camshaft seats.
This step secured the spark plugs within the head.
The following step of the reassembly attached the valve cover to the head.
The timing chain was now fitted around the camshafts as well as the crankshaft.
This step connected the oil pan to the completed crankcase.
The following step of the reassembly involved rebuilding the carburetors and attaching them to the engine.
This step involved the separate components of the air box being reassembled.
The following step was the last, making sure the air box was secured to the carburetors.
- Note: Following these steps, group 13 was able to successfully put the Honda Motor back to its original state. These steps should be followed carefully when reassembling the Honda CBR600 F2 motor. If there are any discrepancies or question on certain components please refer to the product evaluation page for pictures and component specifics.
The following is a summary of how Honda originally assembled the motor in the early 90's in contrast to the procedures that group 13 took during gate four.
The original assembly for the 1994 Honda cbr600f2 engine was done in the following manner. The engine works its way through an assembly line where the components and subsystems are attached in a predetermined manner. The engine starts its assembly with just the block, and the engine components are put in place as it progresses through the line. First, the crankshaft is bolted to the bottom of the block so that the pistons can be fed through the top of the cylinders. When the pistons are in the cylinders, the crank arms are bolted on the crankshaft to allow movement. Next, the oil pan is bolted on the bottom of the engine block to ensure the crankshaft is protected as it works its way through the rest of assembly. The series of gears that make up the transmission are assembled separately, and then added to the transmission area of the block. When these gears are in place, the clutch basket (which was also assembled separately) is connected to the end of the transmission shaft. The top of the transmission is then bolted on the block to complete the transmission assembly. Since the cylinder head is a high tolerance subsystem, it is assembled separately from the assembly line and bolted to the top of the engine block as a whole. When assembling the cylinder head, the valves must be set in place with the valve springs on top, and then the valves are connected to the springs using two small pins. After the cylinder head is bolted on the block, the timing chain fed into the engine block with the chain tensioner from the crankshaft spindle up to the top of the cylinder head. The camshafts are then bolted into place while wrapping the timing chain around the sprockets of the camshafts. The valve cover is then bolted on over the cylinder head covering the camshaft assembly. The carburetor’s are another complex subsystem and are assembled at a separate time. When they are brought to the assembly line, they are bolted to the intake side of the cylinder head. The final part of assembly is attaching the air filter/ air box to the top of the engine via the carburetor system. When the air box is attached, the assembly is complete and ready for installation.
The following summarizes the dissection of the Honda motor and the reassembly performed by group 13.
For the most part, the assembly of the engine used the same procedure for disassembly, only in reverse order. During disassembly, we started by disconnecting the air box, carburetors, cylinder head, etc. and finished with the transmission. When we started to reassemble the engine, we started with the transmission assembly and worked our way through using the same process ending with the carburetors and air box. The only portion of reassembly that differed from disassembly is the introduction of the pistons into the cylinder. The fact that the piston rings need to expand in the cylinder makes it difficult to keep the rings compressed while sliding the pistons into place using a tool called a ring compressor. Since our group did not have this tool, we were able to work around this procedure due to the fact that the piston rings were not originally with the pistons. The reassembly of the engine was completed in a relatively quick manner by successfully adding each component the same way that they came out.
These following revisions contain changes that could be made to the Honda motor on the system level. These consist of major changes affecting performance and reliability as well as other important aspects regarding the engine.
The angle of the cylinders in relation to the incoming air.
When changing the angle of the cylinders, this will allow for a smoother flow of air travel going from the intake to the cylinders. When the air flow is subjected to a higher degree angled junction, it creates turbulence in the flow and can somewhat restrict performance. With this minimal change of the angle, the air flow will have a more linear path for air flow, thus creating a slight increase in performance. Changing the angle of the cylinders has a societal impact because of the improved performance of the engine as a whole. With increased engine performance, the popularity of the product will be increased within the target audience. Also, with an increased air flow the engines efficiency will be slightly higher. With a more efficient engine the product will operate in such a way that more beneficial when dealing with environmental concerns.
Having the transmission housing detachable from the engine block.
This design revision is directed towards the ability to remove the transmission assembly from the engine block. This revision will allow users to slide the entire transmission assembly out through the side of the block. In order to make this design effective, the transmission assembly will be enclosed in a compact casing, the casing will be resting on sliders that will allow the entire casing to be removed easily. This casing will be bolted to the engine block to ensure the transmission does not slide during operation. This design is an excellent way to increase serviceability of the product. This design consideration addresses some societal concerns in the way that the transmission is improved for the people who work with repairing motorcycle transmissions.
With the introduction of econ mode to the engine, the engine will now be able to run more efficiently at the discretion of the user. With econ mode enabled the engine will have the ability to shut down a cylinder, as well as adjust the timing of the engines firing order. The efficiency of the engine will be greatly increased when running in econ mode because when dropping one cylinder the amount of fuel used for that cylinder will be saved. This feature will be an excellent economic revision because of the amount of money being saved with increased fuel economy. Also, it is more environmental friendly due to the fact that it is producing fewer emissions.