Valve Adjustment Spreadsheet

[BackRoadBruce]

I've posted a valve adjustment Excel spreadsheet based on the CBX Club worksheet:



Valve Clearance Spreadsheet (metric)



The sheet is set up for metric entries. Clearances falling outside the recommended .06 - .13mm (060 - 130) settings get highlighted in red.

[kbart1]

this spreadsheet is great however i have a couple questions. i spent the last few months riding my bike after restoring it back to its former glory, more or less. now the riding season has ended so i have decided to pull the cam cover and check the valve clearances using the factory honda manual method. my readings go from anywhere between .06mm to .15mm. most of the larger readings are on the exhaust side of the head. in the spreadsheet mike nixon recommends .10mm for the readings. not that i don't want to be bang on and he is the GURU of these things but if i had some .09mm and .11mm is it worth changing out those shims as well? i only have 5 valves reading .10mm so i would need to change out 19, ouch! if i could leave the .09mm and .11mm valves it would mean changing out only 15 shims, better! the manual recommends .06mm - .13mm just HOW critical is this? the manual also states that the shims come in .05mm increments however when i went through 24 spare shims i have from a bad head there are a lot more increments than the .05mm as stated in the manual? lastly, after i cleaned all my spare shims and put a micrometer to them not one measured as stamped on the shim, every one was slightly over, for example a shim stamped 295 was 299 and so on, is this normal? the reason for my asking these questions is i have never removed any shims while the motor is in the bike. even though i have the 2 little factory tools for doing this job i am still dreading it. any input would be much appreciated.

thanks a lot guys!
kent

[EMS]

Kent: Removing the shims is really not that difficult with a pick and a magnet or tweezers. But I would not worry about the difference between 0.09 or 0.11mm and 0.10mm. Having the clearance too tight would be of concern, however, yours are well withing the specifications. Also, the shims are never exactly what it says. When measured carefully with a micrometer, you will get a different reading than the nominal. I measure mine and then sort them accordingly.

[kbart1]

getting back into this valve shim issue. lets say hypothetically that i don't have the EXACT shim to make the .10mm clearance but i could do either the .09mm or the .11mm clearance. which way do you go if you can't be dead on at 10mm. when you say "too tight" you mean UNDER the .06mm for example. i am assuming that you would go for the .09mm as over time this would where and the gap would become larger????

thanks
kent

[EMS]

getting back into this valve shim issue. lets say hypothetically that i don't have the EXACT shim to make the .10mm clearance but i could do either the .09mm or the .11mm clearance. which way do you go if you can't be dead on at 10mm. when you say "too tight" you mean UNDER the .06mm for example. i am assuming that you would go for the .09mm as over time this would where and the gap would become larger????

thanks
kent

No. The gap does not get larger, it gets smaller. Over time, the valve and the valve seat wear on each other and the valve works its way into the valve seat. As a result, the valve moves up in the valve guide towards the cam and the gap gets smaller. That's why you should always adjust the valves on the looser side of the tolerance, i.e.: give the valve and cam more clearance. As far as the shim is concerned, you pick the "thinner" shim.

[kbart1]

that makes sense to me now. thanks for that info. NOW, what are the dangers of turning the crank in a COUNTER clockwise direction when doing the valves? i had a shim get stuck under a lobe and had to REVERSE the direction of the crank to get it out. it was only about 1/8th of a rotation IF THAT. should i be concerned? i got thinking about it at wondered what could possibly happen by reversing the direction of the motor? am i worrying for no reason/

thanks
kent

[steve murdoch icoa #5322]

Kent, nothing to worry about in reversing the crank an 1/8th of a turn.

Watching the football game from Calgary and seeing all the snow, i am assuming your riding is done for the year?

[kbart1]

thanks steve.

ya, the cbx is off the road. as of right now i am going through the valve train and have stripped it down to clean and polish stuff in anticipation of next spring. having my wheels polished and adding more bits here and there over the winter. my wing is still insured though until mid December. hopefully i will get out a few more times before that insurance comes off!!! i am trying to soften up the wife so i can find another project, would love to find a clean original '79 to play with over the winter. we'll see.

thanks
kent

[kbart1]

well. checked and adjusted all the shims. all good now. and yes it WAS pretty easy. have my cam cover in being ceramic coated while it's apart. one thing i noticed with the cam cover though is on the INSIDE of the cover over the 1-3 exhaust camshaft the cover is dis-colored. looks like it is more of a tan color than the rest of the interior of the cover. from what i can tell it looks as though that portion of the camshafts gets hotter than the rest of the cams. is this a common occurrence? when i bought the bike i discovered that the same cam was trashed along with the journals in the head. looked to be lack of oil possibly. is there an issue with keeping the 1-4 cam journals lubricated? i don't want to see the same thing happen to this motor. bike runs great just the dis-coloration has me concerned. also, while the cam chains are exposed i thought i may adjust them. is there any practical tip for getting access to the rear cam chain adjusting bolt WHILE the carbs are on. my little 10mil wrench or ratchet won't let me reach in there? any tips?

thanks guys!
kent

[EMS]

Do you have all the oil pool plates in place?

[kbart1]

yup, all the plates are in place. there are only plates on the intake cam and i am talking about the exhaust cam left bank. it is almost as if oil is not making its way all the way out to the #1 journal for example. don't get me wrong, oil IS pooled in the head in that area it's just that the INSIDE of the cam cover is a LITTLE discolored there? may be nothing to worry about. just wondering if anybody else has seen this?

thanks
kent

[Briank1]

hi folks, i have most of my gaps close to correct except one which has a gap of .26 its an exhaust valve on number 2 cylinder most of the rest need small adjustments, im not mechanical minded should i worry or just get a shim to close the gap thanks folks from Ireland

[pmcburney]

Link no worky for me.

[NobleHops]

Link no worky for me.

It’s 18 years old

[CBX-tras]

Kurt from KMCarburetor.com made a sheet that you can use either metric or inch measurements and you enter the desired tolerances that gives you the shim number to use. It's a great time saver.
I have it but can't seem to copy it, to here.

I'll ask Kurt to post it.