Help Valve clearence?

[Steve]

...and for measuring those "half" sizes ("x" sizes), a digital caliper comes in very handy. A 6 inch model is all I use. This is about $16 from Harbor Freight.



When using the "x" sizes, you can really fine-tune your clearances. This tool also comes in handy when checking your carburetor float height, clutch plate thicknesses, etc.


Thank you for your indulgence,

BassCliff

When looking for a caliper, be sure to look for that little tip that comes out the end, and is shown in the bottom right corner of BassCliff's picture. That little tip fits nicely on the lip where the bowl gasket sits so you can use the flat end of the caliper to measure the float height. I mention this because not all calipers have what is officially known as a "depth gauge", so shop carefully. Harbor Freight has a cheaper caliper, but it does not have that feature.

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[CCMcC]

x-sizes

Steve,

Thanks for the clarification on the "x" size shims. I wondered if there wasn't a way to "fine tune" the clearance. Very helpful.

BassCliff,

An unrelated question: Would that digital caliper be suitable for checking the journals on a crankshaft, or would one need a micrometer?

Thanks,

Caleb

[bwringer]

I've found and corrected several tight valves on a couple of different bikes, and so far none have been permanently damaged.

The bike starts running so crappy that they don't generally get ridden far enough to do damage.



However, I will say that a bike with intake leaks CAN and WILL damage its exhaust valves -- lean mixtures run very hot.

For want of four 99 cent o-rings, my GS850's original cylinder head was lost. Long, but true story.

[BassCliff]

An unrelated question: Would that digital caliper be suitable for checking the journals on a crankshaft, or would one need a micrometer?

Hi Mr. CCMcC,

Gee, I don't know. Someone with more engine building experience would know better. But I would think that you'd want to use something with more precision than a $10 digital caliper. (The above Harbor Freight unit just went on sale!)


Thank you for your indulgence,

BassCliff

[Steve]

An unrelated question: Would that digital caliper be suitable for checking the journals on a crankshaft, or would one need a micrometer?

A digital caliper can certainly be used to check journals on a crank, journals on a cam, cam lobe lift, any number of things, but ... (you just know there's always a big butt in there ) ... the cheapest ones might not be the ones to do the job. Some of the cheapest calipers have an accuracy of 0.01" or maybe 0.005". To measure journals, you don't want anything worse than 0.001" just as a quick check. At the machinist's shop they go out yet another decimal point for accuracy. Those calipers cost a bit more, but are not necessary for most of what we do to our bikes. I have a Cen-Tech caliper that has accuracy similar to the one in BassCliff's picture, 0.0005.

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[CCMcC]

Thanks

Thanks for answering my question. I thought I'd ask because I have an '81 CB650 basket-case and have been needing to check the crankshaft journals to order bearings.

[Steve]

You snuck in a HONDA question?

Shame on you.

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[CCMcC]

Duly nailed! What's the appropriate penance?

[tkent02]

Duly nailed! What's the appropriate penance?

I think you should be forced to ride a Honduh for a whole hour!
That will teach you!

[Nessism]

A micrometer that reads down to .0001" is necessary to properly measure a crank. Calipers are useless for a task like that.

[Steve]

I think you should be forced to ride a Honduh for a whole hour!
That will teach you!

Not sure that's enough.

I do that for hours on end and still end up here.

.

[Marine36]

I did it. I got the zip tie method to work and inventoried my shims.
I got the spread sheet from Mr. Steve. However, the method for measuring valve clearance on BASSCLIFF's web site differs from my Clymer Manual.

I would guess that BASSCLIFF is basing his info on a Suzuki manual. Will someone please confirm.

[CCMcC]

A micrometer that reads down to .0001" is necessary to properly measure a crank. Calipers are useless for a task like that.

Thank you. And once I get that done and the Honduh back together, if that happens sometime before I expire, I'll do the required penance.

C.

[BassCliff]

I would guess that BASSCLIFF is basing his info on a Suzuki manual. Will someone please confirm.

Hi Mr. Marine36,

Yes, my guide describes the "Suzuki method".

I also have that same 850-1100 Clymer manual for my bike. I usually refer to both for perspective but tend to favor the Suzuki Shop manual.

For this particular procedure the Suzuki method will "unload" the cam on that side of the motor, giving more accurate measurements (take two measurements at the same time). Using the other method (taking one measurement at a time) it seems that as you point each lobe up, the other lobe on that side starts pressing on the shim/bucket/valve assembly, possibly affecting the measurements.

I'd also like to hear from those who've done a lot more valve checks than I.

Thank you for your indulgence,

BassCliff

[Marine36]

I am having a problem with intake valves 3 and 4. Originally I was unable to get my smallest feeler guage (.0015 in.) between the lobe and shim. The original shim was 2.70 for both. I installed 2.65 shims. Using the Suzuki method for testing clearance I still cannot insert my smallest feeler guage into the space between the lobe and shim. Using Clymers method I can get a .002 in feeler in #3 but still no luck with #4. I believe this has to do with the load on the camshaft. I want to try 2.60 x shims but cannot find any.

All other valves have .002 to .003in clearance using the Suzuki method as described by BASSCLIFF.

Any suggestions are greatly appreciated.