Proper way to measure valve clearances?

[Squidley]

Ok Fellas,

I'm working on an '86 with 38000 miles on it and we are checking the valve clearances. Now I have always checked for valve clearances with the lobes facing upward 180 degrees away from the valves. The manual, like everything Yamaha does, is complicated to say the least. I find when I measure it my way that all the clearances are good except the intakes on #2. How the manual states is to go by TDC and the lobes should be facing away from eachother. My issue with this is that the lobe is already starting to load up on the shim as I can't get the feeler gauge all the way through. I need some help for you boys in how you have done this and what you know...PLEASE

[FROG MAN]

How often should one check valve clearance. I'm going to do a compression test on my 84 soon. Is that a good indication of a problem?

[mm482]

"Now I have always checked for valve clearances with the lobes facing upward 180 degrees away from the valves."

Thats the way I have been checking valve clearance for the last forty years.

Earl

[pegscraper]

As long as it doesn't get less than the minimum gap, it should be fine. If it is less, I'd open them up a little.

 

That's odd, really. They should be the same anywhere on the base circle. The base circle of the cam should not have any runout.

[Squeeze]

We've discussed this on our Vmax Board and we did come to Answer "stick to the Point where Yammi refered to". In other Words, check where the Cams should be by the Book, not by your Mind. We have had a Vmax in November which was so tight on one EX Valve, we nearly had to undo the Cam to get the Shim out of the Bucket. It did go out with a groove grinded into the J-Tool and on the very last Micrometer of Elevation.

 

If you don't get the Feeler in the Books Position, the Clearance is too tight.

[Dano]

So it's possible when I checked mine on the bench last year that it didn't get done correctly then? I ass-umed lobes 180d up would be sufficient, but it looks like with Squids understanding that the tolerances would read a heck of a lot tighter with the lobes "sweeping" into play.

Wonder why they (Yamaha) couldn't have just set it up for lobes to be 180d up for the reading?

I will try to ask local dude tomorrow who may have some understanding of this.

 

Where you at trying it this way, Brad?

 

Dan

 

He's gone now!!

[Squeeze]

So it's possible when I checked mine on the bench last year that it didn't get done correctly then? I ass-umed lobes 180d up would be sufficient, but it looks like with Squids understanding that the tolerances would read a heck of a lot tighter with the lobes "sweeping" into play.

Wonder why they (Yamaha) couldn't have just set it up for lobes to be 180d up for the reading?

I will try to ask local dude tomorrow who may have some understanding of this.

 

Where you at trying it this way, Brad?

 

Dan

 

He's gone now!!

 

If you followed the Books Procedure with turning for so and so much Degrees for each change of Cam and Cylinder you have nothing to worry about.

 

Why they didn't use common Cam Position ? Hard to tell, i think you would use a off TDC Position and that's not what they wanted to do because off TDC is a unrelated, variable Position ?

[BradT]

My issue with this is that the lobe is already starting to load up on the shim

 

I agree you have to rotate the cam away from TDC or a couple lobes will be touching and starting push some valves downward.

 

I agree with Pegscraper the base circle should be round and true.

 

Brad

[Squidley]

I ass-umed lobes 180d up would be sufficient, but it looks like with Squids understanding that the tolerances would read a heck of a lot tighter with the lobes "sweeping" into play.

 

I will try to ask local dude tomorrow who may have some understanding of this.

 

Where you at trying it this way, Brad?

 

Dan

 

I agree you have to rotate the cam away from TDC or a couple lobes will be touching and starting push some valves downward.

 

I agree with Pegscraper the base circle should be round and true.

 

Brad

 

 

This is exactly what I am saying, I was always taught that you needed to slide the feeler gauge completely through the opening to be sure of an accurate measurement. When I do it by the book, I can get the feeler somewhat through, but then it engages the lobe of the camshaft.

I'll try to take some pics tonight to perhaps get a better understanding that we can all focus on, Thanks for all your comments

[Squeeze]

Folks, it doesn't matter what we all think WOULD BE right.

 

Yammi has given us Specs for Clearance of the Cams in a given Position and Definition(off lowest Cam Point). For that Point is a given Clearance measured and specified. If we want to do the Cleaance Setting right and check it as stated in the Specs, we need to stay with the given Procedure. Period.

 

 

 

Of course they could have given us other Clearance Specs for lowest Cam Position(180 ° to Lobe) but they didn't. Why or why not and everything else is discussable, but that's academic.

[Flyinfool]

FWIW

I took my '88 in to the dealer for a tuneup and checkup at 36,000.

The dealer told me that It is not worth the effort to check the valve clearance till 60K.

He stated that he has never seen one that needed adjusting with under 60K.

I trust that statement since it is a dealer turning down work as unneeded in a slow economy.

I will go back to him.

[BuddyRich]

There is more than one instance in which the manual was wrong due to a language barrier or just being written incorrectly. The clearance spec if for an unloaded position and unless you specify TDC on the firing stroke you may begin to load up a valve in just a couple of degrees. So pointing up is totally unloaded and I stick to that.

[Squeeze]

There is more than one instance in which the manual was wrong due to a language barrier or just being written incorrectly. The clearance spec if for an unloaded position and unless you specify TDC on the firing stroke you may begin to load up a valve in just a couple of degrees. So pointing up is totally unloaded and I stick to that.

 

Of Course you can do what ever you prefer, but the Misinterpretation or Translation Problem isn't an Issue here. If you look through various Shop Manuals, 1Gen, 2Gen, Vmax, whatever V4 and Year and Language you always will find the same Procedure.

 

oh, btw, the Position by the Book is TDC on firing Stroke of each Cylinder

 

 

 

Regarding the checking the Clearance later than the quoted 26000 mls ... We have had one Vmax where, as stated above the Shim nearly didn't got out the Bucket. The Bike had 29000 mls on the Odo. Granted, the Vmax Riders are tougher on the Motor and this will hammer the Valves more into the Heads as a Venture Rider, but nevertheless it may be better to stay at the suggested Service Schedule. That's because you won't hear anything from your Valve Train until the Valve is burnt up and burning a Hole into the Piston.

 

A Dealer turning down this Job isn't a positive Argument here. This is a rather non-funny Job and you possibly learn some new Words until your done. It's not the Measuring and Shim out/Shim in Process, the Culprit is getting the Valve Covers off and back on the Motor with the Gaskets in Place. I can see a Dealer knowingly make you feel good about "saving some Money" and deal with eventual Consequences later.

[skydoc_17]

Perhaps I can shed a bit of light on this subject. At one time, a camshaft grinding machine used a "template" and the movement of the Grindhead was hydraulically controlled. The entire Camshaft lobe and static diameter of the Camshaft were ground at one time and the static diameter and the lobe ellipse were both ground to the same tolerance. Modern Production Camshaft Grinding Machines are C.N.C. (Computer Numerical Controlled) and the Lobe and Static diameter are actually ground in two different operations. The Lobe ellipse is ground to + or - .0005 or five tenths of one thousandths. Where the operation for the static diameter is ground separately and the tolerance has NO + but can be - .005 or negative five thousands on the Static outside diameter. The procedure in the Yamaha Service Manual positions the Camshaft at the beginning of the tighter tolerance Lobe Ellipse thus guaranteeing the proper valve lash adjustment.

If we take the static diameter to the minimum of the tolerance which would be -.005 and set the valve lash to the static diameter, (with the lobe at 180 degrees rotated) then you have effectively set the valve lash too tight by .005 which would be way too tight.

I hope this has cleared up why it is important to set the valve lash to the Yamaha spec.

Earl

[Squeeze]

Perhaps I can shed a bit of light on this subject. At one time, a camshaft grinding machine used a "template" and the movement of the Grindhead was hydraulically controlled. The entire Camshaft lobe and static diameter of the Camshaft were ground at one time and the static diameter and the lobe ellipse were both ground to the same tolerance. Modern Production Camshaft Grinding Machines are C.N.C. (Computer Numerical Controlled) and the Lobe and Static diameter are actually ground in two different operations. The Lobe ellipse is ground to + or - .0005 or five tenths of one thousandths. Where the operation for the static diameter is ground separately and the tolerance has NO + but can be - .005 or negative five thousands on the Static outside diameter. The procedure in the Yamaha Service Manual positions the Camshaft at the beginning of the tighter tolerance Lobe Ellipse thus guaranteeing the proper valve lash adjustment.

If we take the static diameter to the minimum of the tolerance which would be -.005 and set the valve lash to the static diameter, (with the lobe at 180 degrees rotated) then you have effectively set the valve lash too tight by .005 which would be way too tight.

I hope this has cleared up why it is important to set the valve lash to the Yamaha spec.

Earl

 

Now this Production Process doesn't make Sense to me, but undoubted, you know what your talking about and this makes a Lot of Sense to me. I think i've learned something right now. Thanks Earl !!

[skydoc_17]

Hey Lutz,

Please let me enjoy this moment, I can now count the times I have had information that you were not aware of ....on ONE FINGER! :crackup::crackup:

Now, back to reality!

The reason for the two operation grinding process is this:

Machine #1 is set up to grind Static diameter of Camshaft, operator is less skilled, machine time is quicker, Surface finish is coarser, tolerance is bigger, thus the less skilled operator. Camshafts are "stockpiled" by not complete, so that can not be taxed as a completed sub-assembly by the state government.

Machine #2 is set-up for the finish Lobe Ellipse Operation. Skill level of operator is much higher, Process takes longer, Grinding wheel must be "dressed" more often, Parts are run in smaller "lots", tolerances are much tighter, thus the higher skill level of the operator. If you needed a lot of Camshafts in a short period of time, you would only need to work ONE operator "overtime" instead of two. Finished Camshaft sub-assemblies taxed would be more in line with finished product (completed Motorcycle) shipped.

It's Just like that.

Earl

[Squeeze]

Hey Lutz,

Please let me enjoy this moment, I can now count the times I have had information that you were not aware of ....on ONE FINGER! :crackup::crackup:

...

 

Sure Earl, enjoy it as long as you want. :happy34::bowdown:

 

 

Your Explanation does make Sense and i figured this is all about Costs. But one should think a secong Phase adds more Risks to the overall Process and double Handling might also cost some Money.

[Dano]

So, for a guy like me to understand, it is the "way of the manual" to measure the tolerance on the "side" of the ellipse, as it's closer to correct tolerance than the "bottom" of the lobe? That would mean that you have to have the mark on the flywheel EXACTLY aligned with the timing mark to make sure you were at the correct angle of the cam lobe to make this measurement. If you were off even a touch, wouldn't this throw your measurement off by a thousandths or so? Is that why they give you latitude on the "between here and there" on the allowed tolerances?

So you are not worried about getting the feeler guages all the way through? Just until you hit the lobe if it is angled slightly downward? Or should it be parrallel to the shim?

The other question here, is there timing marks for #3 and #4? I've honestly never paid attention. Or do you have to "figure out" the degrees of rotation starting after TDC at #1? The book shows to do #1, then 3,4 and #2 last.

Probably come up with some more questions after this!

 

Thanks Lutz and Earl for a long-time coming discussion on this.

 

I will definately be redoing mine in the future, as I probably screwed it up, and I'm glad I didn't write it up yet!

[Squeeze]

Well, the Timing Marks are very hard to find/see.

 

What we have always done is to find T1 in firing TDC and worked from there. Turned the Crank for about the called Angle, feeled the TDC of the next Cylinder, checked, corrected if necessary, turned Crank to the next Angle, feel the TDC, repeat ...

 

I use a modified old Spark Plug (as an TDC Finder Tools) to insert into the Plug Thread and feel TDC and a T-Handle with a 30 (or 32mm, not sure atm) Socket to turn the Crank. At least four Hands are Way better than only two. The Cams Lobes are showing up and outwards on one Head and up and inwards on the other Head during that.

[Dano]

Have you found the relationship of the shim to the side of the ellipse to be parrallel? And will the feeler guage slide all the way thru? Just curious so I can do it right the next time, or correct what I did wrong the last time!

 

Dan- who can be stoopid sometimes!

[Squidley]

Dan,

 

The manual is very vauge on all of it, I'm definitely not impressed with it. It will give you the mark for TDC on #1 and then it states that you rotate so many degrees to get to TDC on the rest of the cylinders. I have to say that I appreciate all the input, especially from you Lutz, but this manual is a PITA. I have helped build 11 second V8's and have always checked my valve clearances 1 way for any and every motor, it has never changed.

 

I went out and read the book several more times and everytime the lobe is starting to engage the shim where the book says to measure, it just isn't making sense to me. I'm not sure exactly what I'm going to do, I might sleep on it for another night in the hopes of some Japaneese epiphany.

 

Thank all of you folks again for the help and sharing of your knowledge

PS I have given thought of timing jump but the bike never indicated anything like that.

[Squeeze]

Have you found the relationship of the shim to the side of the ellipse to be parrallel? And will the feeler guage slide all the way thru? Just curious so I can do it right the next time, or correct what I did wrong the last time!

 

Dan- who can be stoopid sometimes!

 

 

The Feeler Gauge has to go all the Way through, just like you know it from all other Engines.

 

Nope, the Shims aren't parallel to the "Side" of the Cam. If you bore a Hole between Lobe and opposite Point, the Angle between this Boring and the Shim would be ?? 65 to 75 ° or so. Hard to tell, i didn't watch out for that.

 

Squeeze, who doesn't like to be the Bearer of bad News :whistling:

[Squeeze]

Brad, that's no Rocket Science at all. It's hard to understand from the Manual, but all you gotta do for a good start on #1 is find the T1 Mark where the Cams are not touching and compressing the Valves.

 

From there turn the Crank for specified Degrees and you should be on TDC of the next Cylinder with the Cams in same Position. I admit its awkward looking but it's the right Position. When changing to the front Bank, you have to turn 70 Degress more because you have to overcome the 70° Bank Angle. But it's all stated in the Manual.

[BradT]

Squeeze if I understand correctly you state that the feeler gauge has to slide all the way through to get an accurate measurment. Also you state that you have to be at TDC. I always pulled a plug and made sure I was at TDC and checked the timing mark. Now going by memory if you do this there is one or two valves that a feeler gauge will not slide through. ?

 

Earl if I understood what you mention, that there could be variance on the back side of the lobe, which could be 5 thousands off. Having said that, if you sent the crank/cam at the correct spot per the manual then almost every lobe is in a different spot yet the tolerance is the same. Some lobes are almost 180 degrees away from the shim and others are touching. ?

 

Maybe I do not understand and/or maybe I just set it in the wrong spot, but I was pretty sure I was in the right spot TDC. ?

 

Again from memory I thought it was one full turn and then 70 degrees to get to TDC 2. 70 degrees being the angle between the two cylinders.

 

BRad

 

Brad

[IH Truck Guy]

I'm not sure exactly what I'm going to do, I might sleep on it for another night in the hopes of some Japaneese epiphany.

 

 

 

Hey Brad,it might help if you took Lonna out for sushi and then slept on it..

It might help with the epiphany...And make ya feel a little Japanese...:D

I have looked at the shop manual too and alot of that is greek to me...

Good luck buddy..