The OBSERVED Valve Clearance thread

[beardyweirdy@me.com_imp]

I left it as is. The fact that the next morning was the first sunny day in ages and I'd arranged a burn out with my mate, who'd just bought a new Bonnie T120, might have had some thing to do with it ;-)

I have to agree with 736, as well as Ulvetanna. Not worth the risk and a tad loose isn't such a bad thing.

I'll see if they move any more next year...

[Ulvetanna_imp]

I left it as is. The fact that the next morning was the first sunny day in ages and I'd arranged a burn out with my mate, who'd just bought a new Bonnie T120, might have had some thing to do with it ;-)

I have to agree with 736, as well as Ulvetanna. Not worth the risk and a tad loose isn't such a bad thing.

I'll see if they move any more next year...

Sounds about right, see what they look like next checkup.

[max]

Clearance at 17.000 km ( first time check ) cb1100 2010 japan import with 7.500 after 7 years.
Used 300 cc. oil over 5.000 km but has used 75 cc since last change ( both times full synthetic ).
Everything looked pristine and shiny, no oil deposits anywhere, very clean inside.
There is a bit of residual oil stuck between the cam lobes and the buckets that has to be good for first startup lubrication, nice bonus, and the cover went on much easyer than taking it out, the coil spade connectors rubber boots go much easyer on with a little grease on the inside of the rubber boots and protect the connectors from water over the little edges on the coil terminals.

spec; ex 0.28 in 0.15 +/- 0.03 mm.


#1 - exhaust .28,.28 intake .16,.17
#2 - exhaust .28,.28 intake .15,.16
#3 - exhaust .27,.27 intake .18,.18
#4 - exhaust .28,.28 intake .16,.15

No adjustment needed.

max

[DaSwami_imp]

OK, I have a question. People refer to these measurements as "loose" or "tight", assuming that the larger measurements mean loose and the smaller mean tight. I always assumed that meant the valve didn't open very much when tight and opened more when loose. However someone explained to me the opposite is true, what we are measuring is valve LASH, the distance between the tip of the lifter or cam lobe and the rocker arm? So that a wider gap means the valve opens LESS because the lifter/lobe has to move further before it contacts the rocker and moves the valve. A smaller gap means that the lifter/lobe contacts the rocker quicker and therefore opens the valve MORE as they move through their travel. Does this make sense?

[jimgl3_imp]

Ult, can't the shims be fished out without pulling the cams? or is that not possible with this motor?

[redbirds_imp]

Ult, can't the shims be fished out without pulling the cams? or is that not possible with this motor?

In this motor the shims are under the "buckets" atop the valves. The cam shafts must be removed in order to access. On an engine with the shims on top they are removed easily by compressing the valve spring and pulling them with a magnet.

OK, I have a question. People refer to these measurements as "loose" or "tight", assuming that the larger measurements mean loose and the smaller mean tight. I always assumed that meant the valve didn't open very much when tight and opened more when loose. However someone explained to me the opposite is true, what we are measuring is valve LASH, the distance between the tip of the lifter or cam lobe and the rocker arm? So that a wider gap means the valve opens LESS because the lifter/lobe has to move further before it contacts the rocker and moves the valve. A smaller gap means that the lifter/lobe contacts the rocker quicker and therefore opens the valve MORE as they move through their travel. Does this make sense?

Exactly.

[SportsterDoc]

Ult, can't the shims be fished out without pulling the cams? or is that not possible with this motor?

In this motor the shims are under the "buckets" atop the valves. The cam shafts must be removed in order to access. On an engine with the shims on top they are removed easily by compressing the valve spring and pulling them with a magnet.

OK, I have a question. People refer to these measurements as "loose" or "tight", assuming that the larger measurements mean loose and the smaller mean tight. I always assumed that meant the valve didn't open very much when tight and opened more when loose. However someone explained to me the opposite is true, what we are measuring is valve LASH, the distance between the tip of the lifter or cam lobe and the rocker arm? So that a wider gap means the valve opens LESS because the lifter/lobe has to move further before it contacts the rocker and moves the valve. A smaller gap means that the lifter/lobe contacts the rocker quicker and therefore opens the valve MORE as they move through their travel. Does this make sense?

Exactly.

Succient explanation, redbirds.

Although a time consuming adjustment, when actually needed, the first link may help explain why Honda used the shim under bucket design:

https://paradiseracing.com/blog/why-shou...r-buckets/

The second link has a good comparison photo:

http://www.koracing.net/productimages/Buckets.jpg

[736cc_imp]

Shim under bucket has a MUCH less chance of “tiddlywinking” when over-revved.
Shim under bucket has MUCH less wear on associated parts which equates to not going out of spec for valve clearance.
Shim under bucket is MUCH more involved to adjust clearance.
Shade tree mechanics probably risk doing more harm than good and should not remove cams in super skillfully built professional factory built engines, and trusting someone else to do so has its risks as well. They are PERFECT from the get-go.
Only abused, over-revved, dirty oil, high mileage modern Japanese motors ever require valve adjustment. Even then, they won’t break or have catastrophic failure. Motocross singles are the exception, they need regular adjusting and rebuilding.

[Houtman_imp]

Thank you for saving us money .

Ult, can't the shims be fished out without pulling the cams? or is that not possible with this motor?

In this motor the shims are under the "buckets" atop the valves. The cam shafts must be removed in order to access. On an engine with the shims on top they are removed easily by compressing the valve spring and pulling them with a magnet.

OK, I have a question. People refer to these measurements as "loose" or "tight", assuming that the larger measurements mean loose and the smaller mean tight. I always assumed that meant the valve didn't open very much when tight and opened more when loose. However someone explained to me the opposite is true, what we are measuring is valve LASH, the distance between the tip of the lifter or cam lobe and the rocker arm? So that a wider gap means the valve opens LESS because the lifter/lobe has to move further before it contacts the rocker and moves the valve. A smaller gap means that the lifter/lobe contacts the rocker quicker and therefore opens the valve MORE as they move through their travel. Does this make sense?

Exactly.

Succient explanation, redbirds.

Although a time consuming adjustment, when actually needed, the first link may help explain why Honda used the shim under bucket design:

https://paradiseracing.com/blog/why-shou...r-buckets/

The second link has a good comparison photo:

http://www.koracing.net/productimages/Buckets.jpg

Succient explanation, redbirds.

Although a time consuming adjustment, when actually needed, the first link may help explain why Honda used the shim under bucket design:

https://paradiseracing.com/blog/why-shou...r-buckets/

The second link has a good comparison photo:

http://www.koracing.net/productimages/Buckets.jpg My CBX's had shim over bucket (24 !) but I never had problems because I never over revved the engines , they were quite easy to change with the right tools.

[Wisedrum]

Here' s another article with good explanation and illustration.

https://www.revzilla.com/common-tread/wh...-adjusters


Wisedrum