Valve adjusting questions

[dingy]

Chart below shows my valve clearances.

 

1983 venture, 36,000 miles

 

Cold engine, setting on workbench.

 

Should I be concerned due to rear head being tighter than front head.

 

The #2 inboard intake is tighter than my smallest feeler of .0015"

 

Should I change the ones that are just outside spec.? I have 3 intakes at .10mm,, spec is .11-.15mm ??

 

Next, I have seen in other threads that there is a loaner valve kit available. Who would I contact about using this??

 

 

 

http://i1007.photobucket.com/albums/af193/gdingy101/valveclearance.jpg

 

 

 

Gary

Edited November 29, 2009 by dingy
spelling

[Venturous Randy]

Yep, it looks like you definitely have some tight valves. It does surprise me that they are so far out of spec with only 36,000 miles on the engine. One thing I would do, especially since you have the engine out, is to pick a couple that are tight and check them at several locations on the cam. I would start just as it comes off the ramp and continue rotating the cam and re-checking until you get to the point of starting onto the ramp. I have been one to just check valve clearance at any point off the lobe, but there are some on here that go to a specific timing point. If nothing else, this may confirm whether there is a difference at any point off the lobe.

I am lucky in that I have an independent bike shop that will let me swap shims for no charge. I first determined what I have and then what I need and then before I started putting new shims in, I tried to see if any I had would work in a different tappet. I believe I did use a few in a different place. You just need to know that if you take out a shim and rotate the cam, it can put a score mark on the edge of the cam lobe.

Yes, I would change the ones that are slightly out or close also because as the engine adds miles, the valves get tighter.

RandyA

[dingy]

One thing I would do, especially since you have the engine out, is to pick a couple that are tight and check them at several locations on the cam. I would start just as it comes off the ramp and continue rotating the cam and re-checking until you get to the point of starting onto the ramp. I have been one to just check valve clearance at any point off the lobe, but there are some on here that go to a specific timing point. If nothing else, this may confirm whether there is a difference at any point off the lobe.

RandyA

 

 

I checked the rear intake cam since it is the farthest out and I am getting about .001" variance around the cam away from the lobe, on all 4 lobes. I shot some cleaner in them and was able to get about .002 overall clearance reading on the #4 inboard intake, still way tight.

 

Thanks,

Gary

[MiCarl]

Gary,

 

I don't have the book here at home but I believe the exhaust spec is 0.16-0.20. It's just the intakes that are 0.11-0.15. If I remember my numbers correctly that means only your #4 exhaust and the one #2 intake are in spec.

 

The reason the exhaust valves have a looser spec is because the hot exhaust gas moves over the stem causing them to "stretch" more when the engine is warmed up. Intake valve stems have cold intake air on them so they don't expand as much.

 

No need to worry about the different wear in rates. In fact, they probably aren't different. Remember the shims come in 0.05mm increments. This means they likely differed by 0.04 the day it was assembled. I believe they're all within that.

 

The tightening is due to the valves wearing into the seat. This happens fastest when the engine is new. Once they settle in the wear slows down. That's why the initial check is at much lower mileage than the regular interval after that. If the initial service was never done it's not surprising that most of them are tight.

[jimmyenglish]

At 52k, on my 86', I had to reshim all but two valves. They weren't horribly out of spec but I changed them nevertheless.

[Yammer Dan]

Gary,

 

I don't have the book here at home but I believe the exhaust spec is 0.16-0.20. It's just the intakes that are 0.11-0.15. If I remember my numbers correctly that means only your #4 exhaust and the one #2 intake are in spec.

 

The reason the exhaust valves have a looser spec is because the hot exhaust gas moves over the stem causing them to "stretch" more when the engine is warmed up. Intake valve stems have cold intake air on them so they don't expand as much.

 

No need to worry about the different wear in rates. In fact, they probably aren't different. Remember the shims come in 0.05mm increments. This means they likely differed by 0.04 the day it was assembled. I believe they're all within that.

 

The tightening is due to the valves wearing into the seat. This happens fastest when the engine is new. Once they settle in the wear slows down. That's why the initial check is at much lower mileage than the regular interval after that. If the initial service was never done it's not surprising that most of them are tight.

 

 

Just looked in book. You are right on specs. Wish I could remember numbers like that!

[MiCarl]

Just looked in book. You are right on specs. Wish I could remember numbers like that!

 

I think Yamaha uses the same specs on every shim/bucket cam they ever made. Means don't have to remember too many.

Edited November 29, 2009 by MiCarl

[Squeeze]

It doesn't matter much regarding Valve Clearance, but you have something mixed up with teh Cylinder Notation.

 

Cyl #1 is left rear

Cyl #2 is left front

Cyl #3 is right rear

Cyl #4 is right front

 

When sitting on the Bike.

 

It matters much if you go with the Manual and turn the Crank to the Position which Yammi says to check the Clearance.

[dingy]

It doesn't matter much regarding Valve Clearance, but you have something mixed up with teh Cylinder Notation.

 

Cyl #1 is left rear

Cyl #2 is left front

Cyl #3 is right rear

Cyl #4 is right front

 

When sitting on the Bike.

 

It matters much if you go with the Manual and turn the Crank to the Position which Yammi says to check the Clearance.

 

 

Would think that after drawing 16 different schematics I would have got that right, put the cyl notation on all the coils.