Valve Clearance Inspection - R. side Cams not right?????

[STPaulK]

On second thought, the gears would have had to also been removed and rotated if the cams were swapped. No way would it run if the lobes were so far off. Forget my theory (but maybe doublecheck the stamping on the camshaft anyway.)

 

[Scooter]

:bump

Jeff, did you get a chance to look at this again???

 

[zooker13]

I think the RH cams are timed 180 off, which would still run without damaging anything but the CMP would be getting pulses at the wrong time but the ECM wouldn't know it so no fault code. The cam sprockets are all the same because the cam bolt flanges are offset and will only fit one way with the markings outward, toward the front.
,

 

[1129VLD]

:bump

Jeff, did you get a chance to look at this again???

Sadly, no. This year has been a *&&^%^! And, it doesn't help that I purchased the Vstrom, which I am really enjoying (hence, not a lot of motivation to get the ST back on line).

 

[970mike]

I am bringing up this very old thread as I ran into the same thing as Jeff did way back in the day. I found out that you need to rotate the engine 720 degrees to complete the cycles of a four stroke motor. If you stop at 360 degrees when rotating the engine you will have the exhaust and intake valves on the inside as Jeff did. I have my problems fixed with adjusting my valves and wanted to let anyone else having issues a way to complete the valve adjustment.

I did call Jeff and let him know my findings.

Here is an article that helped me find you need to go 720 degrees.

Four Stroke Cycle Engines

A four-stroke cycle engine is an internal combustion engine that utilizes four distinct piston strokes (intake, compression, power, and exhaust) to complete one operating cycle. The piston make two complete passes in the cylinder to complete one operating cycle. An operating cycle requires two revolutions (720°) of the crankshaft. The four-stroke cycle engine is the most common type of small engine. A four-stroke cycle engine completes five Strokes in one operating cycle, including intake, compression, ignition, power, and exhaust Strokes.

Intake Stroke

The intake event is when the air-fuel mixture is introduced to fill the combustion chamber. The intake event occurs when the piston moves from TDC to BDC and the intake valve is open. The movement of the piston toward BDC creates a low pressure in the cylinder. Ambient atmospheric pressure forces the air-fuel mixture through the open intake valve into the cylinder to fill the low pressure area created by the piston movement. The cylinder continues to fill slightly past BDC as the air-fuel mixture continues to flow by its own inertia while the piston begins to change direction. The intake valve remains open a few degrees of crankshaft rotation after BDC. Depending on engine design. The intake valve then closes and the air-fuel mixture is sealed inside the cylinder.

Compression Stroke

The compression stroke is when the trapped air-fuel mixture is compressed inside the cylinder. The combustion chamber is sealed to form the charge. The charge is the volume of compressed air-fuel mixture trapped inside the combustion chamber ready for ignition. Compressing the air-fuel mixture allows more energy to be released when the charge is ignited. Intake and exhaust valves must be closed to ensure that the cylinder is sealed to provide compression. Compression is the process of reducing or squeezing a charge from a large volume to a smaller volume in the combustion chamber. The flywheel helps to maintain the momentum necessary to compress the charge.

When the piston of an engine compresses the charge, an increase in compressive force supplied by work being done by the piston causes heat to be generated. The compression and heating of the air-fuel vapor in the charge results in an increase in charge temperature and an increase in fuel vaporization. The increase in charge temperature occurs uniformly throughout the combustion chamber to produce faster combustion (fuel oxidation) after ignition.

The increase in fuel vaporization occurs as small droplets of fuel become vaporized more completely from the heat generated. The increased droplet surface area exposed to the ignition flame allows more complete burning of the charge in the combustion chamber. Only gasoline vapor ignites. An increase in droplet surface area allows gasoline to release more vapor rather than remaining a liquid.

The more the charge vapor molecules are compressed, the more energy obtained from the combustion process. The energy needed to compress the charge is substantially less than the gain in force produced during the combustion process. For example, in a typical small engine, energy required to compress the charge is only one-fourth the amount of energy produced during combustion.

The compression ratio of an engine is a comparison of the volume of the combustion chamber with the piston at BDC to the volume of the combustion chamber with the piston at TDC. This area, combined with the design and style of combustion chamber, determines the compression ratio. Gasoline engines commonly have a compression ratio ranging from 6:1 - 10:1. The higher the compression ratio, the more fuel-efficient the engine. A higher compression ratio normally provides a substantial gain in combustion pressure or force on the piston. However, higher compression ratios increase operator effort required to start the engine. Some small engines feature a system to relieve pressure during the compression stroke to reduce operator effort required when starting the engine.

Ignition Event

The ignition (combustion) event occurs when the charge is ignited and rapidly oxidized through a chemical reaction to release heat energy. Combustion is the rapid, oxidizing chemical reaction in which a fuel chemically combines with oxygen in the atmosphere and releases energy in the form of heat.

Proper combustion involves a short but finite time to spread a flame throughout the combustion chamber. The spark at the spark plug initiates combustion at approximately 20° of crankshaft rotation before TDC (BTDC). The atmospheric oxygen and fuel vapor are consumed by a progressing flame front. A flame front is the boundary wall that separates the charge from the combustion by-products. The flame front progresses across the combustion chamber until the entire charge has burned.

Power Stroke

The power stroke is an engine operation Stroke in which hot expanding gases force the piston head away from the cylinder head. Piston force and subsequent motion are transferred through the connecting rod to apply torque to the crankshaft. The torque applied initiates crankshaft rotation. The amount of torque produced is determined by the pressure on the piston, the size of the piston, and the throw of the engine. During the power Stroke, both valves are closed.

Exhaust Stroke

The exhaust stroke occurs whenspent gases are expelled from the combustion chamber and released to the atmosphere. The exhaust stroke is the final stroke and occurs when the exhaust valve is open and the intake valve is closed. Piston movement evacuates exhaust gases to the atmosphere.

As the piston reaches BDC during the power stroke combustion is complete and the cylinder is filled with exhaust gases. The exhaust valve opens, and inertia of the flywheel and other moving parts push the piston back to TDC, forcing the exhaust gases out through the open exhaust valve. At the end of the exhaust stroke, the piston is at TDC and one operating cycle has been completed.

 

[ST Gui]

Bookmarked.

 

[dduelin]

I am bringing up this very old thread as I ran into the same thing as Jeff did way back in the day. I found out that you need to rotate the engine 720 degrees to complete the cycles of a four stroke motor. If you stop at 360 degrees when rotating the engine you will have the exhaust and intake valves on the inside as Jeff did. I have my problems fixed with adjusting my valves and wanted to let anyone else having issues a way to complete the valve adjustment.

I did call Jeff and let him know my findings.

Here is an article that helped me find you need to go 720 degrees.

Four Stroke Cycle Engines

A four-stroke cycle engine is an internal combustion engine that utilizes four distinct piston strokes (intake, compression, power, and exhaust) to complete one operating cycle. The piston make two complete passes in the cylinder to complete one operating cycle. An operating cycle requires two revolutions (720°) of the crankshaft. The four-stroke cycle engine is the most common type of small engine. A four-stroke cycle engine completes five Strokes in one operating cycle, including intake, compression, ignition, power, and exhaust Strokes.

Intake Stroke

The intake event is when the air-fuel mixture is introduced to fill the combustion chamber. The intake event occurs when the piston moves from TDC to BDC and the intake valve is open. The movement of the piston toward BDC creates a low pressure in the cylinder. Ambient atmospheric pressure forces the air-fuel mixture through the open intake valve into the cylinder to fill the low pressure area created by the piston movement. The cylinder continues to fill slightly past BDC as the air-fuel mixture continues to flow by its own inertia while the piston begins to change direction. The intake valve remains open a few degrees of crankshaft rotation after BDC. Depending on engine design. The intake valve then closes and the air-fuel mixture is sealed inside the cylinder.

Compression Stroke

The compression stroke is when the trapped air-fuel mixture is compressed inside the cylinder. The combustion chamber is sealed to form the charge. The charge is the volume of compressed air-fuel mixture trapped inside the combustion chamber ready for ignition. Compressing the air-fuel mixture allows more energy to be released when the charge is ignited. Intake and exhaust valves must be closed to ensure that the cylinder is sealed to provide compression. Compression is the process of reducing or squeezing a charge from a large volume to a smaller volume in the combustion chamber. The flywheel helps to maintain the momentum necessary to compress the charge.

When the piston of an engine compresses the charge, an increase in compressive force supplied by work being done by the piston causes heat to be generated. The compression and heating of the air-fuel vapor in the charge results in an increase in charge temperature and an increase in fuel vaporization. The increase in charge temperature occurs uniformly throughout the combustion chamber to produce faster combustion (fuel oxidation) after ignition.

The increase in fuel vaporization occurs as small droplets of fuel become vaporized more completely from the heat generated. The increased droplet surface area exposed to the ignition flame allows more complete burning of the charge in the combustion chamber. Only gasoline vapor ignites. An increase in droplet surface area allows gasoline to release more vapor rather than remaining a liquid.

The more the charge vapor molecules are compressed, the more energy obtained from the combustion process. The energy needed to compress the charge is substantially less than the gain in force produced during the combustion process. For example, in a typical small engine, energy required to compress the charge is only one-fourth the amount of energy produced during combustion.

The compression ratio of an engine is a comparison of the volume of the combustion chamber with the piston at BDC to the volume of the combustion chamber with the piston at TDC. This area, combined with the design and style of combustion chamber, determines the compression ratio. Gasoline engines commonly have a compression ratio ranging from 6:1 - 10:1. The higher the compression ratio, the more fuel-efficient the engine. A higher compression ratio normally provides a substantial gain in combustion pressure or force on the piston. However, higher compression ratios increase operator effort required to start the engine. Some small engines feature a system to relieve pressure during the compression stroke to reduce operator effort required when starting the engine.

Ignition Event

The ignition (combustion) event occurs when the charge is ignited and rapidly oxidized through a chemical reaction to release heat energy. Combustion is the rapid, oxidizing chemical reaction in which a fuel chemically combines with oxygen in the atmosphere and releases energy in the form of heat.

Proper combustion involves a short but finite time to spread a flame throughout the combustion chamber. The spark at the spark plug initiates combustion at approximately 20° of crankshaft rotation before TDC (BTDC). The atmospheric oxygen and fuel vapor are consumed by a progressing flame front. A flame front is the boundary wall that separates the charge from the combustion by-products. The flame front progresses across the combustion chamber until the entire charge has burned.

Power Stroke

The power stroke is an engine operation Stroke in which hot expanding gases force the piston head away from the cylinder head. Piston force and subsequent motion are transferred through the connecting rod to apply torque to the crankshaft. The torque applied initiates crankshaft rotation. The amount of torque produced is determined by the pressure on the piston, the size of the piston, and the throw of the engine. During the power Stroke, both valves are closed.

Exhaust Stroke

The exhaust stroke occurs whenspent gases are expelled from the combustion chamber and released to the atmosphere. The exhaust stroke is the final stroke and occurs when the exhaust valve is open and the intake valve is closed. Piston movement evacuates exhaust gases to the atmosphere.

As the piston reaches BDC during the power stroke combustion is complete and the cylinder is filled with exhaust gases. The exhaust valve opens, and inertia of the flywheel and other moving parts push the piston back to TDC, forcing the exhaust gases out through the open exhaust valve. At the end of the exhaust stroke, the piston is at TDC and one operating cycle has been completed.

There aren't 5 strokes in a complete cycle of a 4 stroke engine or else it would be called a 5 stroke engine.

I think you added one - the ignition event - which occurs during the compression stroke.

The service manual has a diagram making it easy to check valves in correct sequence and not get lost in the order. Check valves for cylinder #1 at top dead center then rotate the crankshaft counter clockwise 90 degrees. Go to check #4 at TDC, then rotate the crank 270 degrees. Check #3 at TDC then rotate the crank the final 90 degrees to check #2 at TDC. 90 + 270 + 90 + 270 = 720 degrees.

 

[970mike]

There aren't 5 strokes in a complete cycle of a 4 stroke engine or else it would be called a 5 stroke engine.

I think you added one - the ignition event - which occurs during the compression stroke.

The service manual has a diagram making it easy to check valves in correct sequence and not get lost in the order. Check valves for cylinder #1 at top dead center then rotate the crankshaft counter clockwise 90 degrees. Go to check #4 at TDC, then rotate the crank 270 degrees. Check #3 at TDC then rotate the crank the final 90 degrees to check #2 at TDC. 90 + 270 + 90 + 270 = 720 degrees.

As long as your cams are installed right it is easy to check the valves.

The service manual also states when installing the cams to make sure you are on the compression stroke but does not say how to check that.

 

[TerryS]

Installing the second cams out of phase with the first also happens with VTR1000F Superhawks/Firestorms. The bike starts and runs fine at low-mid revs but apparently runs out of puff at 8000 or so. I presume there is some intake or exhaust resonance that the engine just doesn't like.

 

[TerryS]

As long as your cams are installed right it is easy to check the valves.

The service manual also states when installing the cams to make sure you are on the compression stroke but does not say how to check that.

On the compression stroke, all valves are closed so both intake and exhaust lobes would be pointing away from the valves. This is also between the inlet valves closing and the exhaust valves opening.

 

[jfheath]

We were taught that the 4 strokes were: intake, compression, combustion, exhaust. Not ignition - as that is a split second event which takes place sometime during the latter stage of the compression cycle - it varies depending partly on how fast the engine is running. It takes a certain amount between making the spark and getting the full force of the explosion, so if the engine is running faster, the spark has to be generated earlier in the compression stroke.

If the piston is moving up and all 4 valves are closed then it is a compression stroke. If the piston is moving up and the exhaust valve is open, then that is the exhaust stroke.
ie it is the position of the valves that determines which stroke it is.

Of course, the spark has got to 'fire' near the top of the compressions stroke. The missing piece of information is that the spark is generated every time just before the pistons reaches top dead centre - no matter whether it is in the compression stroke or the exhaust stroke. Both cylinders on one side get the spark at exactly the same time whether it has fuel to ignite or not. So you dont have to worry about how it knows which cylinder to fire.

You can work out whether the piston is moving up or down from the TDC timing mark. If it was showing Tdc, then after that it is moving down. You can work out where it has got to by the total angle of movement of the wrench on the crankshaft bolt. [edit] Hmm. Just realised - I don't know which way the engine normally rotates. You have to turn the engine counterclockwise - I assume so that the bolt isn't untightened, but does the engine turn this way normally ? I don't know.[/edit]

Note that the manual describes two different methods for installing the cam shafts. One is for when you have removed the cams from both sides, the other if just one side has been removed.

When looking for info about the valve timing, it is described in two places in the workshop manual, and it helps to read both. One is in the maintenance section - Section 3. The other is in Cylinder head and valves - Section 8. Some info is duplicared. Some appears in just one section. I find that it helps to read both. Don't forget the bits in italics in the left margin.