CCT change without removing the valve cover?
Thread Starter
Member
Squid
Joined: Sep 2006
Posts: 76
From: North Carolina
CCT change without removing the valve cover?
OK,I am getting ready to install APE cct's on my Hawk.What I would like to know is:can I bring the piston to tdc and change without having to remove the valve cover?What I gather from reading is that the chain is not under tension at tdc so if its at tdc why the need to remove the valve cover?Im a big fan of the easy way.:-D
Senior Member
SuperSport
Joined: Dec 2005
Posts: 963
From: Sunshine Coast, Australia
You need to make sure that when you are at TDC you are on the compression stroke with both valves closed. If you are on the exhaust stroke at TDC you are in trouble. The way to ascertain this is by removing the valve covers.
There is a shortcut on here for you to follow that allows you to do this without removing the valve covers. You remove one of the bolts from the front valve cover and it allows you to see the cam lobe for the exhaust valve, therefore allowing you to identify the compression stroke.
I have done this a couple of times and it works just fine. Do a search for the instructions, and follow them exactly.
There is a shortcut on here for you to follow that allows you to do this without removing the valve covers. You remove one of the bolts from the front valve cover and it allows you to see the cam lobe for the exhaust valve, therefore allowing you to identify the compression stroke.
I have done this a couple of times and it works just fine. Do a search for the instructions, and follow them exactly.
Senior Member
SuperBike
Joined: Nov 2004
Posts: 1,315
From: Richmond, Virginia
Shayne is right. Here's the deal: one revolution of the camshaft equals 2 revolutions of the crankshaft. Thus you will see TDC in the window TWICE for each revolution of the camshaft. Only one of those 2 times are both valves actually closed. That's why you need to visually verify where the camshaft actually is.
Trust me, if you screw it up, it will jump timing. Been there before...
Trust me, if you screw it up, it will jump timing. Been there before...
Slacker
Superstock
Superstock
Joined: Jun 2005
Posts: 489
From: San Antonio, TX
One way of finding TDC on the compression stroke is to use a compression gauge.
On other engines where the spark plug holes are easy to reach, you can simply hold your thumb over the spark plug hole while turning the engine. When compression builds up, the pressure will blow your thumb off the top of the hole. Then you turn crankshaft to nearest TDC for that cylinder.
You MIGHT even try installing the spark plug loosely with only 3-4 threads, and turning the engine quickly with a wrench. When you hear a hissssss coming from that plug, you are building compression.
On other engines where the spark plug holes are easy to reach, you can simply hold your thumb over the spark plug hole while turning the engine. When compression builds up, the pressure will blow your thumb off the top of the hole. Then you turn crankshaft to nearest TDC for that cylinder.
You MIGHT even try installing the spark plug loosely with only 3-4 threads, and turning the engine quickly with a wrench. When you hear a hissssss coming from that plug, you are building compression.
Senior Member
SuperSport
Joined: Dec 2005
Posts: 963
From: Sunshine Coast, Australia
I am no good at posting up links to other threads, so I have gone to the Australian VTR site that I am a member of, and have copied the instructions I wrote on there. Here they are below.
This is a short cut to the normal process of removing the valve covers to check the timig marks, and ensure the cylinder is on TDC on the compression stroke.
Do all the usual stuff such as removing inspection plugs, and spark plugs. Then instead of taking the valve covers off do the following:
Squat down in front of the bike with the front wheel in front of your chest. You will see the front cylinder in front of you. As you face the bike observe the bottom left valve cover retaining bolt. (This is on the right hand side of the bike, and on the opposite side of the head to the cam gears.) Remove this bolt. Shine a small torch in through the hole. You will see the base circle of the camshaft.
Turn your engine in a counter clockwise direction until the FT timing marks line up for the front cylinder. This is as per normal. Now go back to your bolt hole and have a look. If the cam lobe is visible and pointing towards the front wheel, it is now TDC on compression. If you can only see the base circle of the cam rotate the engine until the timing mark is visible again, then re-check. It should then be correct. You can now change the CCT.
For the rear cylinder rotate the engine counter clockwise again 270 degrees until the RT timing mark lines up. As you have already identified the correct engine rotation on the front cylinder there is no need to do it again. Change the rear CCT.
All done. Drink a beer.
This is a short cut to the normal process of removing the valve covers to check the timig marks, and ensure the cylinder is on TDC on the compression stroke.
Do all the usual stuff such as removing inspection plugs, and spark plugs. Then instead of taking the valve covers off do the following:
Squat down in front of the bike with the front wheel in front of your chest. You will see the front cylinder in front of you. As you face the bike observe the bottom left valve cover retaining bolt. (This is on the right hand side of the bike, and on the opposite side of the head to the cam gears.) Remove this bolt. Shine a small torch in through the hole. You will see the base circle of the camshaft.
Turn your engine in a counter clockwise direction until the FT timing marks line up for the front cylinder. This is as per normal. Now go back to your bolt hole and have a look. If the cam lobe is visible and pointing towards the front wheel, it is now TDC on compression. If you can only see the base circle of the cam rotate the engine until the timing mark is visible again, then re-check. It should then be correct. You can now change the CCT.
For the rear cylinder rotate the engine counter clockwise again 270 degrees until the RT timing mark lines up. As you have already identified the correct engine rotation on the front cylinder there is no need to do it again. Change the rear CCT.
All done. Drink a beer.
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