Author Topic: Another valve adj. question - slightly different.  (Read 1500 times)

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Offline timdhawk

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Another valve adj. question - slightly different.
« on: December 19, 2013, 03:40:54 PM »
78 CB750. I'm putting everything back together after a motor "mishap". I'm running a Cyclex cam and adjustable cam gear. The cam only has the "notch" on the end but not the hash marks to line up with the cam cap like the OEM one does. The cam gear doesn't have any timing marks either.
So in trying to set my valve lash by doing it the way the manual says, ("T" 1.4 mark aligned and the cam notch pointed upward) I was running into the issue with one of the valves being under some tension and being unable to set the lash.  So I searched and found the way described in the most recent "valve setting" post - http://forums.sohc4.net/index.php?topic=132672.0 - and so I did it that way. I got all the valve lashes set but then I noticed that the notch on the cam is pointed down instead of up when I cross check the cam lobe positions against the way the manual says. Does that make sense?

Am I okay since I set everything the way described in the other post? or is it even possible that I somehow got the cam 180* off and still able to set the valves?
In deeper than I should be...

Offline thep1pe

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Re: Another valve adj. question - slightly different.
« Reply #1 on: December 19, 2013, 03:49:31 PM »
Are you taking the piss? I hope this does not turn into another 180 degree out cam thread. :D

Offline Don R

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Re: Another valve adj. question - slightly different.
« Reply #2 on: December 19, 2013, 03:56:25 PM »
I think you may be close to another mishap. Proceed slowly after you read up on it. There has been a slew of bent valves recently.
 The crank turns 1 time while the cam turns 1/2 turn. the next rotation it will be back where it was. If you can't adjust the valves when following the procedure something is wrong.
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Re: Another valve adj. question - slightly different.
« Reply #3 on: December 19, 2013, 04:49:18 PM »
78 CB750. I'm putting everything back together after a motor "mishap". I'm running a Cyclex cam and adjustable cam gear. The cam only has the "notch" on the end but not the hash marks to line up with the cam cap like the OEM one does. The cam gear doesn't have any timing marks either.
So in trying to set my valve lash by doing it the way the manual says, ("T" 1.4 mark aligned and the cam notch pointed upward) I was running into the issue with one of the valves being under some tension and being unable to set the lash.  So I searched and found the way described in the most recent "valve setting" post - http://forums.sohc4.net/index.php?topic=132672.0 - and so I did it that way. I got all the valve lashes set but then I noticed that the notch on the cam is pointed down instead of up when I cross check the cam lobe positions against the way the manual says. Does that make sense?

Am I okay since I set everything the way described in the other post? or is it even possible that I somehow got the cam 180* off and still able to set the valves?

If the notch on the cam is directly down (or up) when you have aligned the crank with the 2.3 on the 'T' mark, then that is good.

The notch on the cam should be flat/pointing to the front or back of the bike horizontally (in line with the cam caps), provided the crank is lined up with the 1.4 on the 'T' mark. This is good as well.

If everything checks out here, then you have your valve timing set good.

If not, then stop everything and get this right, otherwise you will end up with bent valves when you turn the crank.

Offline bjbuchanan

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Re: Another valve adj. question - slightly different.
« Reply #4 on: December 19, 2013, 08:21:07 PM »
When I set the valves on my rebuilt engine I noticed that my last two valves to be set were "loose" with the notch down. All of the others were notch up at 1.4 and 2.3. Since you have an engine sitting in front of you make it easy on yourself. If the top of the egg (the lobe) is facing down in to the engine then adjust it, that means you are at the base of the lobe and it is A ok to go for it.

This is obviously for engines with no cover on
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

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Offline dave500

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Re: Another valve adj. question - slightly different.
« Reply #5 on: December 19, 2013, 09:17:04 PM »
Are you taking the piss? I hope this does not turn into another 180 degree out cam thread. :D

ahh?the old 180 out cam trick?i think the whole world should know about that by now?im not biting though.

Offline bjbuchanan

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Re: Another valve adj. question - slightly different.
« Reply #6 on: December 19, 2013, 10:14:23 PM »
Are you taking the piss? I hope this does not turn into another 180 degree out cam thread. :D

ahh?the old 180 out cam trick?i think the whole world should know about that by now?im not biting though.

I remember reading that thread, I was still sort of new here but not new to engines and really just common sense. I couldn't get how people were behind the idea, a mindfcuk for sure
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline dave500

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Re: Another valve adj. question - slightly different.
« Reply #7 on: December 20, 2013, 01:57:19 AM »
its folklaw myth derived from installing an automobile distributor 180 out from the camshaft.

Offline timdhawk

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Re: Another valve adj. question - slightly different.
« Reply #8 on: December 22, 2013, 12:07:19 PM »
I missed the one sentence in the manual that said "turn the crankshaft so that the base circle of the cam is up". That was my issue... attention to detail!
In deeper than I should be...

Offline ekpent

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Re: Another valve adj. question - slightly different.
« Reply #9 on: December 23, 2013, 06:06:41 AM »
Make sure what the valve lash is supposed to be set for your aftermarket cam. My mild Andrews cam I have in an RC836 kit called for both the intake and exhaust to be set at .004, little bigger than a stocker.