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Adjusting Valves

mike in idaho
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Posts: 411
Joined: Sun Jan 29, 2012 9:18 pm
Location: orofino, idaho

Post by mike in idaho » Tue Jan 01, 2013 2:57 pm

It isn't necessary to get real anal about having the rotor stay exactly on the tdc mark to adjust the valves. Anywhere within 45° of tdc will have both cam lobes solidly on the base circle of their respective cam lobes. I know I will get flack for saying this from all resident experts on this list. Next time you adjust valves, leave the feeler guage in place and roll the engine around a bit and you'll see it will move a fair amount before the feeler guage gets tight(valve opening).
'65 YG1
'65 CB160
'66 CL160
'66 CL77
'78 XS650
'79 GL1000
'69 T100R
'68 TR6
'69 T120
'72 750 Commando
my company car is a Kenworth

LOUD MOUSE
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Posts: 7817
Joined: Mon Aug 15, 2005 8:23 am
Location: KERRVILLE, TEXAS

Post by LOUD MOUSE » Tue Jan 01, 2013 10:12 pm

FLACK FOR SURE.
HONDA DIDN'T MAKE THESE ENGINES TO BE CLOSE TO TUNE.
Do as you do but I think HONDA "HAD A BETTER IDEA!!!!!!
HNY. ............. lm
mike in idaho wrote:It isn't necessary to get real anal about having the rotor stay exactly on the tdc mark to adjust the valves. Anywhere within 45° of tdc will have both cam lobes solidly on the base circle of their respective cam lobes. I know I will get flack for saying this from all resident experts on this list. Next time you adjust valves, leave the feeler guage in place and roll the engine around a bit and you'll see it will move a fair amount before the feeler guage gets tight(valve opening).

RobCL72
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Posts: 5
Joined: Sun Jul 01, 2018 9:08 pm

Post by RobCL72 » Wed Sep 18, 2019 10:27 pm

Hi, i'm adjusting the valves on my CL72 right now...and I am wondering how I can tell if the cylinder I am working on is at the TDC of the compression stroke and not the exhaust stroke...?

Or doesn't it matter, just use T and LT?

But, set on "T", neither valve on the right side of the motor is free at all. Setting the rotor to LT, I check the left side, and think there was some play.

But, I'm a little confused on the rotor/T and LT procedure, only because there seems to be valve train play or freeness, not when the T and LT marks directly line up, but on one side or the other of the mark. Does that make sense? The free play in the cycle of the motor is more free on either side of the marks.[/i]

mike in idaho
honda305.com Member
Posts: 411
Joined: Sun Jan 29, 2012 9:18 pm
Location: orofino, idaho

Post by mike in idaho » Thu Sep 19, 2019 7:22 pm

T is for top dead center on the right cylinder, LT is for the left cylinder. Put it on the "T" mark for which every side you're adjusting, if the valves are tight turn it around one more full turn.
'65 YG1
'65 CB160
'66 CL160
'66 CL77
'78 XS650
'79 GL1000
'69 T100R
'68 TR6
'69 T120
'72 750 Commando
my company car is a Kenworth

ELMST616
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Posts: 18
Joined: Sat Jan 04, 2020 11:14 pm
Location: Redmond, WA. USA

Re: Adjusting Valves

Post by ELMST616 » Sat Sep 18, 2021 6:54 pm

Bring this back alive because i have a 64 CA77 and there is no LT on the rotor. So, how do you know when it is tdc for the left side?

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Tim Allman
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Posts: 434
Joined: Tue Dec 02, 2014 9:25 am
Location: Guelph, Ontario, Canada

Re: Adjusting Valves

Post by Tim Allman » Fri Oct 08, 2021 9:13 am

The marks are really just a convenience. In the absence of a TDC mark you can just pull the spark plug and use a probe -- a screwdriver works well -- to feel where TDC is. The angle at which the probe contacts the piston makes it possible to bind the probe, possibly damaging the spark plug threads so be careful. In particular, don't allow the piston to rise without holding the probe and keeping it moving freely. Turning the crankshaft from the right side while feeling the piston position on the left is awkward to say the least so enlisting a friend might be a good idea. It's also possible to buy a TDC probe.

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