Valve check procedure?

TeeCat · Posted: February 9, 2009, 11:44 am Post subject: Valve check procedure?

It seems to me that there was a very thorough valve check/adjustment procedure documented here, but upon searching, I can't seem to find it. Am I mistaken?

It has been very cold in Maryland of late, and the bike has been sitting, except for about once every two weeks when I fire her up and bring her up to temperature with varying rpms... I don't just let her sit and idle because I want her to have top end oiling. Roads are too dirty to take her out.

She has been running beautifully, but I have noticed a slight tick - if I had to guess I'd say from the left exhaust valve area - that only seems audible at idle. It may have been there before, but might not have been evident then because I just put proper reverse cone muffs on her.

I have never checked the valve clearance and I need to do it after I get my tires on and when I get time, but I was wanting to find a really detailed procedure so I don't screw up.

Has it been documented here?

any thanks!

TC

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

pretty simple, make sure it's cold. make sure the side you are checking is at TDC compression stroke, so both valves are closed. There should be a little bit of wiggle on the intake and exhaust tappets so thats the easy way to tell. Check both with your feeler guage, a slight amount of drag is all you are looking for on the feeler, not crazy tight. adjust accordingly. then spin the motor so the other side is at TDC compression and repeat.

TeeCat · Posted: February 9, 2009, 3:21 pm Post subject: Re: Valve check procedure?

oldschool, thank you! I'll save this for when I'm ready.

Now, couple more things:

So... assuming the plugs are out and I'm turning the motor with a ratchet, how do I know when the side I'm working on is at TDC? Forgive me... I'm taking baby steps. And what feeler gauge size? And can I get to the intakes without puling the carbs? Looks like I can.

And there are gaskets behind the covers, right? Should I have new ones on hand before I do this?

Thanks! Smile

TC

BigGeorge · Full Member Joined: Apr 13, 2008 Posts: 267

TeeCat, not to rain on your parade but you are not doing your engine any favor by starting it and running it every 2 weeks. An engine produces water vapor and unless the motorcycle is ridden approx 10 miles it will not warm up sufficiently to burn off the water vapor it produces which will end up in your crankcase of all places and turn your oil a milky color. Just thought I would run that by you. Also a simple way to find TDC is put your thumb over the sparkplug hole and turn the engine over with the ratchet and you will feel your thumb being pushed off the spark plug hole as the engine comes up on the compression stroke. If you are not feeling your thumb being pushed away then you are on the exhaust stroke and will need to turn the engine 1 additional revolution..........BG

kingwj · Posted: February 9, 2009, 7:02 pm Post subject: Re: Valve check procedure?

If the side you are not working on is at top dead center the side you are working on is at top dead center. Use the timing mark to find TDC, it's under the alternator cover on the left side of the motor.. The cylinder you want to adjust will have both valves loose. The other cylinder will have both valve tight. This is overlap, a point where the exhaust valve is not quite closed and the intake is beginning to open. You do not need to remove the carbs.

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

pull Intake and Exhaust tappet covers off on the side you want to start with. Pull stator cover off and turn motor till the line on the rotor lines up with the TDC mark on the stator. Then you know both pistons are at TDC. Check both rocker arms, if both intake and exhaust are wiggly, adjust that side. if one is depressed then rotate the motor again till the TDC marks line up on the stator and rotor.

Can anyone else chime in as to what the Exhaust and Intake clearances are for his bike??? i don't have my manual close.

No gaskets needed. the covers have little rubber ones in them.

EDIT: king beat me to it.

TeeCat · Posted: February 9, 2009, 7:28 pm Post subject: Re: Valve check procedure?

George, thanks for this. I think the main reason I run it is so that the fuel doesn't varnish, though I do keep Sta-bil in the fuel.

I'll try the tip for finding TDC.

TC

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

if you have Stabil in the tank and it's chilly out you should be fine. (i think gas goes bad alot quicker in hot/humid weather.)

tacoswild · Posted: February 9, 2009, 10:28 pm Post subject: Re: Valve check procedure?

teecat, you may need to at least loosen the carb clamps until you can wiggle the carbs before you can get the intake covers off. Mine needs that, maybe the later bikes don't.

whynot2 · Posted: February 9, 2009, 10:48 pm Post subject: Re: Valve check procedure?

TC,
Get a couple of manuals, Clymer, Haynes, Chilton (out of print ), but my favorite for some reason, and of course,Yamaha. Bookfinder.com will get you used copies cheap. Read and compare. The more you know about your bike the better it gets. Is it a '73? The '73 has gaskets not o rings. And somewhere along the way Yamaha changed the valve setting for years '71 and up to 0.004" intake and 0.006" exhaust.
Take your time, have fun with it, Greg

TeeCat · Posted: February 9, 2009, 11:18 pm Post subject: Re: Valve check procedure?

Thanks, guys.

I have a Haynes, but find it lacking. I'll need to supplement it with some other manuals.

Yup... she's a '73.

TC

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

Haynes manuals are terrible. I had one for my old GPz750 and i threw it out. Clymer all the way.

xsleo · Posted: February 10, 2009, 4:15 am Post subject: Re: Valve check procedure?

TeeCat at WWW.yamaha-motor.com/s.../home.aspx has tech data listed. go to parts, then year, then go down the list till you get to the tech data. it will give you the specs and any updates on the specs.

TeeCat · Posted: February 10, 2009, 7:30 pm Post subject: Re: Valve check procedure?

Thanks, guys! I flagged this thread for later use. Smile

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