Topic: TDC to adjust valves

[Burke]

According to the manual, you rotate the engine till according to your T (1/4) on you plate line up with the indicator mark, then to tell wich is at TDC you should feel which arms are loose....None of mine are loose. How do I tell if this happens?

Same thing happens with 2/3.

Do 1 and 4 both end up at TDC together? and 2/3 and so on?

I went ahead and adjusted 1&4. 4 I could adjust, but on 1 I could not adjust the exhaust.(couldnt insert feeler) I rotated then I could insert the feeler in on 1.   Would I be correct to assume that the first time, when I could adjust 4 and not 1, that 4 was at TDC?

[cbass*gxc]

I just did this and I took the spark plug out and looked in with a flash light.  Seems to work well.

1 & 4 do not hit TDC at the same time when 1 is at TDC 4 is at the bottom. 

This is for a 550 right?  If so do you have the repair manual for it?  If not let me know I have the whole thing as one pdf file and I can send it to you.

[Bodi]

Yes, 1 & 4 are at TDC at the same time. 2 & 3 are opposite, ie at BDC when 1 & 4 are at TDC.
If you can't feel any clearance on any valve adjustment then some are too tight. If you loosen all 8 off a few turns, you should be able to find the "loose" ones pretty easy, and adjust them. The "tight" ones will still be tight I think, unless you loosen the tappets a whole lot. Basically you can adjust both valves if the piston is at TDC on compression, and this is the best way to set them. You can do some others but it doesn't really save much time and I find it easier to just set 1 at compression TDC and set the #1 tappet clearances, turn the crank "forward" 1/2 turn to 2/4 TDC, set valves on 2, turn 1/2 turn to 1/4 TDC, set valves on 4, turn 1/2 turn to 2/3 TDC... and finally set valves on 3. (the firing order is 1-2-4-3)

[Burke]

bike is a 77' CB750

So...I could set the valves (intake and exhaust) when I have 1/4 at TDC for both 1 & 4, then the same for 2 & 3?

[TwoTired]

bike is a 77' CB750

So...I could set the valves (intake and exhaust) when I have 1/4 at TDC for both 1 & 4, then the same for 2 & 3?

No.
1 & 4 are at TDC at the same time, but only one of them is between the compression and fire stroke where you set the tappet clearance.  The other is between the exhaust and intake stroke where the tappets can still be on the cam lobes..  To do the other cylinder you rotate the crank 360 degrees.  2 and 3 are done in the same fashion relative to the marks on the crank timing plate.

If all your tappets are too tight, then take out a spark plug and feel when the compression stroke occurs. on that cylinder. at the end of it the marks for the cylinder on the timing plate should line up.  Set the tappet clearance for that cylinder.  Rotate the crank 360 and do the other cylinder's tappets.

Cheers,

[Burke]

Ok.I remove the plugs on 1 &4 stick a finger on the hole and  I am feeling for the "pressure" correct?

The other one should have a valve open so no pressure, right?


Then set adjust the "Compression" cylinder, then rotate. Correct?

[tinyrobot]

You don't even need to stick your finger in there.  You will hear the cylinder release compression.

Rotate until 1:4 is TDC.  1 being in the compression stroke.  Adjust both valves on cyl. 1, exhaust on 2, intake on 3.  Then rotate forward 360 and adjust both on 4, intake on 2 and exhaust on 3.

Intakes valves are a .05mm shim, exhaust are a .08mm for stock valves.

[scondon]

  To tell if you're on the compression stroke for #1 cylinder, spin the motor until you see #1 intake valve begin to rise(leftmost cylinder as you sit on the bike). When it begins to rise continue turning the motor until you hit the 1/4 "T" mark. You are now at TDC of compression stroke on #1.  tinyrobot's listed the procedure to follow.

[cbass*gxc]

My bad. I thought the that only one was up at a time.