Measuring Valve Clearances

[Hooligans]

Fellow Vmax enthusiasts, a scenario/question I pose for you;

When setting the cams for valve clearance measurement I followed the Yamaha Manual procedure as follows;

Set T1 mark, make sure rear cams have timing marks pointing up and Cyl 1 is at TDC

Rotate 180 Degrees and Cyl 3 is at TDC

Set T2 mark, make sure front cam timing marks point up and Cyl 2 is at TDC

Rotate 180 degrees and Cyl 4 is at TDC

Am I misinterpreting the manual?

Some users on this forum have indicated to simply set the cams lobes up on the cylinder you are measuring, but the resulting measurements are vastly different than results from the aforementioned procedure.

In other words; in accordance with my interpretation of the shop manual my clearances are in check, but following user initiated advice my clearances are way off.

I should say that the reason for checking them is I switched my 89 cams with 96 cams (a long winded story for another post in another section of the forum). I should also say that compression is good across all four cylinders with little to no variance so I will leave well enough alone.

But for the purpose of knowing how to do it right, which method is correct?

I am positive my motor is timed properly because after much trial and error (and 2 new cam chains and 4 new camshafts) my timing marks are dead on. :bang head:

This aint my first rodeo when it comes to building engines but definitely my first V4.

Pray tell oh ye who knows,

"Reading furnishes the mind only with materials of knowledge; it is thinking that makes what we read ours."

- John Locke


hoo·li·gan noun \ˈhü-li-gən\
<H2>: a usually young man who does noisy and violent things as part of a group or gang


</H2>

 

[gamorg02]

when going by the timing marks where are your valve lobes?

 

[Hooligans]

Cam lobes are facing up but more towards each other, definitely not directly up. I will take a picture when I get home and post the difference.

hoo·li·gan noun \ˈhü-li-gən\

: a usually young man who does noisy and violent things as part of a group or gang

 

[gamorg02]

mine was such a pain to see the timing marks i did it with lobes up, but i never checked against the actual timing marks, thats a really good question. paging mr. morley.

 

[Rusty McNeil]

If the ex. and int. cam lobes for a given cylinder are "up but pointing towards each other" I question the cam timing.

Usually, since the valves are canted away from each other, if the cam base circle that is 180 out from the lobe tip is directly facing the the bucket face at TDC, which they should be, this will mean the tips are leaning away from each other, due to the valves being angled away from each other, not towards.


Since they turn the same direction I don't think they'll ever come into position where they point at each other.


When you set them did you go by little holes in the cams that indicate proper position when lined up with the mark in the cam cap?


Reason I ask is that for one identical cam there is a small hole and an even smaller hole towards the end. They are few degrees apart.


If its used at the rear of the motor you use one size hole for reference and if used at the front of the motor you use the other hole for reference.


Sorry if I am stating the obvious.


In answer to your original question I can't remember off that's right or not.


The front two cylinders TDC is 180 out from each other, As are the rears.
The two left cylinders share a crank pin as do the right two. The V angle is 70 degrees so somewhere in the valve setting sequence your going to go 430 degrees to get TDC when moving from back to front bank or vice versa. If you do it in order that I did it.


In essence ANY motors valve clearance should be able to be set as long as the lobe tip for the valve being set is pointing exactly away from the bucket/lifter etc so that is at the point where its "loosest"


That's why it's fine to just set them by "lobe is up" method as long as you understand the geometry involved.


I do it that way with the caveat that oftentimes I will pull a spark plug and stick a rod down the hole and rock the cylinder back and forth (or piston up and down) until I know for sure that its at TDC, but the cams MUST be clocked properly for this to work.

Even then I will say looking at the flywheel marks is more accurate since a few degrees of crank rotation are easier to see than trying to find exact TDC by measuring the piston top since right around TDC a few degrees of crank rotation create
very little up or down motion on the piston.

Oh,

The T2 mark that has the extra little "band" defined on it? Ignore that extra mark and use only the big one . That extra mark is to create a band within which a timing light should flash if you were to ever use one.

 

[one2dmax]

I just do it with the lobes up away from the bucket

 

[maleko89]

I just do it with the lobes up away from the bucket

The same...I don't use the flywheel markings at all.

 

[gamorg02]

I just do it with the lobes up away from the bucket

The same...I don't use the flywheel markings at all.

have either of you checked it against timing?



-----

is anyone else doing a valve check at the moment can say if the lobes away vs on timing marks are different on their bike?

 

[one2dmax]

no point and never bothered

 

[maleko89]

Garrett, that's a negatory. The reason for me not to was because the Almighty Morley told me not to back in the day. lol I hear a heavenly church choir singing in the background......

 

[gamorg02]

Garrett, that's a negatory. The reason for me not to was because the Almighty Morley told me not to back in the day. lol I hear a heavenly church choir singing in the background......

me too. and i still dont' question it but it goes back to rusty, thinking maybe something going on with cams.

OP: what is the difference in measurements?

 

[Hooligans]

Sorry fellas, went a little heavy on the sauce last night and forgot all about this, tonight I will break out the camera and take pictures of exactly what I'm talking about, before I cover it up and bring this beast to life.

If it works either way then I guess it doesn't really matter, but the difference in clearance was significant.

Also a previous poster may have been right about the lobes pointing up and away from each other...I don't remember off hand, again, I will post pictures tonight.

Thanks for your input.




"He that is taught only by himself has a fool for a master."

- Hunter S Thompson


hoo·li·gan noun \ˈhü-li-gən\

: a usually young man who does noisy and violent things as part of a group or gang

 

[Hooligans]

A quick websearch has yielded this;

http://www.pcwracing.net/instructions/Valve Spring Instructions.pdf

Don't know who did this write up (they are probably on this forum), his method is somewhat different from the Yamaha manual but very well written and with good pictures.

If you look at the second and third pictures you will see what I mean, when he sets the timing marks with what I am assuming is the T1 mark or equivalent (picture 2), the cam lobes are facing up and in (picture 3). This is where you should take valve clearance measurement for Cyl 1, or at least that's how I interpreted the manual.

I'm not quite sure why he took the cover off and didn't just look through the window for the T1 mark.

My point is - if you take the cam lobes from 10 and 2 at TDC and change them to pointing straight up, there will be a significant change in valve clearance (I measured up to .003in difference), and your timing marks will be nowhere close to TDC.

But, if the more experienced guys on this forum have been doing it the other way with success for a long time, then I am sure either way works. Just an observation.


"The only source of knowledge is experience"

- Albert Einstein

hoo·li·gan noun \ˈhü-li-gən\

: a usually young man who does noisy and violent things as part of a group or gang

 

[one2dmax]

He does not go into any detail at all on the valve lash setting/measurement except at the end where he gives the amount of gap to look for.

 

[Lance Gothard]

If the ex. and int. cam lobes for a given cylinder are "up but pointing towards each other" I question the cam timing.

Usually, since the valves are canted away from each other, if the cam base circle that is 180 out from the lobe tip is directly facing the the bucket face at TDC, which they should be, this will mean the tips are leaning away from each other, due to the valves being angled away from each other, not towards.


Since they turn the same direction I don't think they'll ever come into position where they point at each other.


When you set them did you go by little holes in the cams that indicate proper position when lined up with the mark in the cam cap?


Reason I ask is that for one identical cam there is a small hole and an even smaller hole towards the end. They are few degrees apart.


If its used at the rear of the motor you use one size hole for reference and if used at the front of the motor you use the other hole for reference.


Sorry if I am stating the obvious.


In answer to your original question I can't remember off that's right or not.


The front two cylinders TDC is 180 out from each other, As are the rears.
The two left cylinders share a crank pin as do the right two. The V angle is 70 degrees so somewhere in the valve setting sequence your going to go 430 degrees to get TDC when moving from back to front bank or vice versa. If you do it in order that I did it.


In essence ANY motors valve clearance should be able to be set as long as the lobe tip for the valve being set is pointing exactly away from the bucket/lifter etc so that is at the point where its "loosest"


That's why it's fine to just set them by "lobe is up" method as long as you understand the geometry involved.


I do it that way with the caveat that oftentimes I will pull a spark plug and stick a rod down the hole and rock the cylinder back and forth (or piston up and down) until I know for sure that its at TDC, but the cams MUST be clocked properly for this to work.

Even then I will say looking at the flywheel marks is more accurate since a few degrees of crank rotation are easier to see than trying to find exact TDC by measuring the piston top since right around TDC a few degrees of crank rotation create
very little up or down motion on the piston.

Oh,

The T2 mark that has the extra little "band" defined on it? Ignore that extra mark and use only the big one . That extra mark is to create a band within which a timing light should flash if you were to ever use one.

Why not mark the flywheel when motor is open and pistons exposed with reference point that is easily seen on oil baffle plate to lndicate tdc of each cylinder then install heads and stuff then check clearance with indicator marks you put on fly wheel and baffle plate

 

[CaptainKyle]

The same...I don't use the flywheel markings at all.

Me 3 never used the markings

 

[Parminio]

@Hooligans No, you are not misinterpreting the manual. You're doing it literally 'by the book'.

It's just that guys that have done it for a long, long time know by experience how to do it and don't have to rely on the marks. If you all placed pictures in this thread you'd see that it's essentially the same thing in the end.

It's sort of like setting timing by ear, or tuning a guitar by ear. Some can do it, others need the timing light / tuner to do it.

In the end, both methods are equally correct.