Jump to content
Sign in to follow this  

Shimming valves - TDC

Recommended Posts

I'm in the process of shimming my valves and I have a question.  I know I started at TDC, but when I took the bolts out of the cam sprocket I had to rotate the primary drive gear bolt  to gain access (just not sure how much).

 

So when I go to install the Camshaft Holder Assembly back on, I know I need to line up the punch mark for the primary drive gear bolt and also line up the cam sprocket with it's index mark, and have the intake cam lobes facing up - but it still seems like I could be off by 180 (or get lucky and be on)?  Is there a way to tell, what am I missing?

 

Thanks

Share this post


Link to post
Share on other sites

I'm in the process of shimming my valves and I have a question.  I know I started at TDC, but when I took the bolts out of the cam sprocket I had to rotate the primary drive gear bolt  to gain access (just not sure how much).

 

So when I go to install the Camshaft Holder Assembly back on, I know I need to line up the punch mark for the primary drive gear bolt and also line up the cam sprocket with it's index mark, and have the intake cam lobes facing up - but it still seems like I could be off by 180 (or get lucky and be on)?  Is there a way to tell, what am I missing?

 

Thanks

The crankshaft only knows what the cam tells it.

There is only ONE TDC...set the crank to TDC and then time the cam sprocket to that. Lobes should be facing the rear of the bike and slightly up.

Hint: Use the flywheel to find TDC...inspection port on ignition cover. Much more accurate...

Share this post


Link to post
Share on other sites

Wow thanks for the quick response, I think I understand what your saying.  Once I align both - I can't be off 180 (or it doesn't really matter).

 

"Hint: Use the flywheel to find TDC...inspection port on ignition cover. Much more accurate..."

 

how do you do this, I can't find any info?

 

thanks

Share this post


Link to post
Share on other sites

<<The crankshaft only knows what the cam tells it.  There is only ONE TDC...>>

 

I know what you meant, but it didn't come out right (at least to me) because the thing that's not clear to most is that the pickup coil for the ignition is on the crank and fires every time you hit TDC.  So you can't be 180 out.

 

All that matters is that the cam marks are lined up at TDC so the cam is in sync with the piston, which is what you were getting at.

 

Jim.

Share this post


Link to post
Share on other sites

Wow thanks for the quick response, I think I understand what your saying.  Once I align both - I can't be off 180 (or it doesn't really matter).

 

how do you do this, I can't find any info?

 

thanks

 

 It's the plug on the ignition cover (left side).   You'll see two marks in there a "F" and a "T".  You want the "T".

 

Jim.

Share this post


Link to post
Share on other sites

Hint: Use the flywheel to find TDC...inspection port on ignition cover. Much more accurate...

that's a good hint sir. Always a PITA to keep looking on opposite sides of the motor when checking. Thanks!

 

Learn something everyday!

  • Like 1

Share this post


Link to post
Share on other sites

Yea it is easier to use the fly wheel. Instead of looking over. To see the crank dimple that's covered in oil.

The T and F markings can be hard to see too. What I do is take a sharpie and mark the T, just makes it easier to see. Specially as my eyes get older. Good tip Doc

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×