Some valve adjustment tips and tricks.

[Django]

I'm sorry, but I guess I have to disagree. That would not be an error in the CB1100 shop manual, but also the CBF and some other Honda shop manuals I happen to know. Also the BMW K1100 shop manual I own would be wrong. All of them suggest, to loose tension for measuring the valves. For my CBF1000F there even is a special tool to release the tension during measuring. It's basic shop knowledge to do so.

However, everybody is free to make his own mista^Wdecisions. I don't count me out of that group.

[LakeWylieJoe_imp]

I'm an open-minded guy, and have been wrong more times than I can count. That being said, can anyone think of a plausible reason why the timing chain tension would need to be released before taking clearance measurements? There are three reasons not to:

1) The intake cam could be out of its intended timing position by as many as 3-4 teeth when you turn the crank to a TDC position to take measurements. The slack on the loose side of the chain can be taken up by the intake cam being forced forward by valve springs it is holding open, resulting in slack between the cams. You can see this happen when turning over the crank by hand--the slack goes from back to front as valve springs push on rear facing intake lobes.

2) The intake cam sprocket can jump a tooth while turning the crank. If this happens, you'll be forced to remove the cams to correct the timing, even of all your valves clearances were perfect. You'd double the work for nothing.

3) Once you remove the cover bolt from the cam chain tensioner, you get to install a new washer when you replace it later. Again, if the clearances are correct, you save that step. That's a small factor compared to the others.

The chain slack does not affect the clearance measurements one iota when the cams are in the correct positions and held down by their holders, any more than a burned out headlight would. The sole function of the chain is to maintain timing between the crank and the cams. Again, one may prove this by taking measurements with and without slack. I've done several times out of curiosity and gotten the exact same result. Besides, the engine runs with no slack, so it certainly isn't hurting anything to leave it on.

The shop manual does have you releasing the tension on the chain in the cam removal section. If you follow the steps exactly as given in the valve clearance steps, you'd be releasing the tension twice.

One example of cascading shop manual errors that show up over multiple bikes (proof they copy general steps from manual to manual in order to not 'reinvent the wheel' each time):

All of the fuel injected 781cc VFRs have a vacuum activated baffle on the top of the airbox that opens and closes to optimize airflow under various running conditions. ALL of the 1998-current VFR factory shop manuals have an incorrect test procedure for that particular system. The manual says if you unplug the neutral wire switch and start the engine, the baffle will be open under some fixed rpm level (around 6,000rpms if I remember right); the default position is closed. Every VFR800 out there, including the three models I had, fail this test. Honda even got me a new ECM under warranty when I demonstrated the failure of that test to the dealer on my 2003. Later, after i tested several other local VFRs, Honda admitted the test as specified in the manual was wrong. The throttle had to be nearly full open (in addition to being in gear or neutral switch disconnected) for the baffle to open. The manuals continue to be sold with this error, even after they became aware of it in 2003. It happens. By the way, the VFR manual does not have you take tension out while making measurements. Neither do any of my cars. It's not general shop knowledge.

When installing a new chain & sprockets on my 2014, my factory manual said to remove the gear position indicator as one of the required steps. That switch was far enough away from the front sprocket that it could be left alone; there was no reason to remove it, so I didn't. The job went off perfectly.

Anyway, I'm open to logic if anyone has a reason (other than following what may be a goof in the book) for releasing the tension from the cam chain before taking measurements.

[Tev62]

Sounds perfectly good to me Joe. Not too long ago I did the valve shims on my 1995 Triumph, 6 of 16 needed swapping. Luckily, they were shim over bucket so no camshafts needed to come out but there is no mention of slackening the timing chain for any measurement or replacement procedure and nor would I expect there to be one. It is ludicrous to suggest the chain tensioner and its little spring has any bearing on these clearances compared to the cam journals. I have spotted glaring errors in my 2018 Triumph Tiger 1200 user manual too, not uncommon.

[Django]

The camshafts of the CB1100 (as in my CBF) run in sliding bearings. That are those holders. The camshafts are specifically beded in the bearings. That's the reason, why the holders are numbered and shouldn't be interchanged. Nevertheless those bearings have some play, otherwise the camshafts couldn't rotate.
When the motor runs, the rotation of the camshafts perfectly centers the camshaft in the bearings. But when it stands still and is opened for measuring the valve lash, the tension of the timing chain pulls the camshaft in its bearing at one end of the camshaft and push it up at the other end of the camshaft. That influences the measurement of the valve lash and that's the reason, why Honda suggests in the Honda workshop manual, to loose the tension before measuring.

[Tev62]

Well I guess the next person who likes to follow the Honda way might do us a favour and measure the valve clerances before slackening off the tensioner and then measure them again afterwards. That would answer this question quite definatively.

[the Ferret]

The exact reason I barely trust the dealership mechanic to fo this job correctly.... when pretty smart guys ( as far as I can tell) cant agree on how to do the job.

[LakeWylieJoe_imp]

I've measured both ways, with and without slack in the chain, a few times as an intellectual exercise. Same results.

My feeler gauges vary in 0.001in steps (~0.025mm). The shims also come in 0.025mm steps.

[max]

Two good video's with very detailed info about valve checks and adjustments.
Valve clearance check;
https://www.youtube.com/watch?v=1ipQ1XI1brU

And valve adjustment;
https://www.youtube.com/watch?v=tbgG3uQgECc

Hope this helps.

[Tev62]

I'm not keen on the way the guy is switching back and forward between inches and mm, it could make it unnecessarily confusing for some people.

[Scotty_imp]

I've measured both ways, with and without slack in the chain, a few times as an intellectual exercise. Same results.

My feeler gauges vary in 0.001in steps (~0.025mm). The shims also come in 0.025mm steps.

Well, there you have it! Thank you for that bit of information and experience.