Really need help with these valves. Now I sure this just ain't right

[Rich:-)]

never mind.. will rethink suggestion and try again..

[Ian T]

 

[Angustoyou]

Sorry kwackboy, got to completely disagree with you about setting them slack and not checking them again, unless I misunderstood what you meant.  (This is entirely possible!)

Valve clearances have upper and lower limits.  On, or between these limits means take no action.  The valve clearances are good and require no further attention until the next scheduled service.  Nothing bad is going to happen, and by altering them nothing will improve.  Your engine will not run better, it will not give more mpg or power, it will not last longer, and yes, you absolutely must check them again at the next recommended interval. 

If any are out of spec, replace the shims to put the spec IN THE MIDDLE of the upper and lower limit.  This is the optimum valve clearance setting.  This allows some movement of the clearances either up or down, and means WHATEVER IS HAPPENING IN YOUR ENGINE will be picked up and corrected at the next check WITH NO DETRIMENT TO YOUR ENGINE OR ITS PERFORMANCE. Valve clearances on most modern engines TEND  to tighten not loosen.  Yours may not though.  If you have set them to maximum in spec clearance, and they loosen a touch, you now have an engine running out of spec. Set them in the middle and you have leeway either way, whatever happens.

It can take 20,000 - 100,000 miles for your engine and all its components to fully bed in.  Until this time each intervention can unsettle it, and result in different tendencies.  Eg, first valve check, 15,000 miles, everything in spec.  Good, as it should be. Do not attempt to fix something that is not broken at this stage.

But we noticed one exhaust valve at maximum.  Hmmmm. Record these results. DO NOT feck ABOUT WITH IT, IT IS FINE.

2nd check, 15,000 miles later
1 inlet valve out of spec, but that exhaust valve that was on maximum, is still on maximum.

Change the inlet shim, aim for middle of spec.    Do not be tempted to remove a cam where all the clearances are still in spec.   Leave it the feck alone if it measures good. If exhaust and inlet are operated by the same cam, and it is coming out anyway, then OK, if you must, change that exhaust shim to bring it to middle spec. Hell, do them all, lets get it perfect. Needed? NO. Sensible?  Not really.  Would I?  No. What the hell, in there anyway, lets get it perfect is understandable, but pointless.  Did you balance the camshaft while it was out? Did you remove and polish the valves, and check/lap the valve seats? Remove, polish and balance the pistons and con rods? Check piston size, bore size and machine to fit? Balance the crank?  Why ever not?  Doing any one of these individually makes no difference.  Do all of them, along with the squish clearance on each piston/head and you now have a blue printed engine. Splendid.  But on a low stress, low performance DL engine? Utterly, utterly pointless.  But it will be deliciously, noticeably smoother. 

On a high spec, high rpm, high power motor for racing, yes please. For anything else you risk disturbing a sound motor by introducing change, which can have unexpected consequences.

Do not attempt to fix that which is not broken.  Wise words that our op may wish he'd heard earlier....

To the op, if it were my engine I'd trust my own measurements and only act on an out of spec measurement, ignore everything else and in the absense of any worrying symptoms, check again at the next scheduled check, while listening out for worrying symptoms.  These are not hi-spec, fragile, tempermental engines, the very opposite in fact. Chill.

[greywolf]

Once an engine is broken in, valve clearances only get smaller unless something else is wrong, like contaminants in the oil. The most wear comes from the valve beating itself into the valve seat. Wear happens slowly in the exhaust valves and glacially in intake valves as the metal is hardened but exhaust heat causes faster wear. Wear on the cam lobes and tappets/buckets is much slower as long as the oil is clean as much less force is involved and there is oil between the cam and bucket, unlike the valve and seat. The bottom line is clearances at the higher end of the spec will last longer than at the lower end.

The difference between one shim and the next size is half the entire clearance range. The idea for long life is to get the clearance somewhere between the middle and high end of the spec. The alternatives are either out of spec or in the low half of the range.

In the unusual case of the clearance being in the middle or in the wide end of the spec, choosing the middle is probably best, but that is an extremely rare choice. The usual choice is somewhere in the wide half or the narrow half of the range. Middle or wide are not really the choices involved. It's almost always wide half or narrow half.

[kwackboy]

Valve clearances where shims are involved only ever get SMALLER. Setting them at the higher end of the range which I've been doing for years in my opinion is best, some mechanics try to get them spot on if they have time.
I own a brand new CB500f and checked the shims at 4000 miles, only two were tight . I set them all at the higher end of the range and apart from unforseen circumstances I can pretty much guarantee they won't need changing again . Despite what manufacturers say in their manuals modern engines are far more reliable with less maintenance needed.

[Hugh Mungus]

I can see the logic Kwackboy, valve clearances will only need checking at service time and probably no shims will need changing which equates to less hassle and less cost.

[Angustoyou]

Note that perfect is the middle of the spec. Not upper or lower limit, middle. This is the optimum clearance.   The optimum is named, with a plus and minus tolerance.  It can be slightly higher or slighty lower than optimum without issue.  This is therefore what to aim for.  Advice to do other than this is not good advice.  Sorry, but it's true.

Most valve clearances do tighten, that is more common, and when they get out of spec, the next available shim size up is designed to take it back to optimum- the middle of the range.  Some do loosen though, and no one knows if your valves will do one or the other, so why risk your engine?  If the manufacturers and design engineers agreed that valve clearances always tighten, it would come with only a minus tolerance, that is, plus zero, minus 0.1 for example.  In that case, only shims of 0.1 would be available.  Hedging your bets by aiming for anything other than optimum puts your engine at risk, hence the word "bet".   

But my advice only comes from years of doing nothing but repairing heads and blocks 6 days a week, and having the engineering theory and qualifications behind it all. Take it or leave it, just don't sell me your bike if you leave it.

[greywolf]

This advice sounds like its origins are from screw and lock nut valve adjusters. Shim under bucket adjusters are a bit different. They are go or no go measurements rather than look for drag at the spec. Typically, once feeler gauges reach around 0.10mm to 1.15mm, they start changing in 0.05mm increments. One leaf is often half the entire specified range. Also, the spec is not listed as +/- but as an acceptable range. For example, EX. : 0.20 - 0.30 mm, not 0.25mm +/- 0.05mm. Suzuki is capable of of a +/- spec as they use it on idle speed setting for example but they specify a range here.

If I had a valve clearance on one exhaust valve that would pass a 0.20mm leaf but not a 0.25mm leaf and another that would pass a 0.15mm leaf but not a 0.20 leaf, I'd replace both with 0.05mm thinner shims since I had the cam out anyway. The exception would be if I got drag on the 0.15mm leaf. Then I'd go 0.10 thinner for that shim. That's what I mean by going for the wider half. I would know both clearances would be well off minimum and below maximum.

I have been helping people with V-Strom valve clearances for over ten years. I have yet to see a single report from experienced users of a clearance growing but there have been a number of reports of clearances reducing, probably over 90% being exhaust valves.

[kwackboy]

I guess all the manufacturers who spend millions developing engines are wrong. 
The specified tollerance levels advised in manuals are minimum - maximum not optimum so adjusting them to the upper limit is perfectly fine and will not cause any issues what so ever.
I've never seen a valve clearance with shims and buckets loosen , can't see how when valve buckets sink over time causing gaps to close. OK in a very rare case the valve may develope a problem or the guide might wear or something similar which you would notice that pretty quickly. Feel free to educate me though.
Tapets on then other hand I've seen loosen alot more because of screw and lock nut coming loose , it's a bad design that's why shims were developed to stop that happening.
Be rest assured when I sell my bikes you don't get the memo.

[Angustoyou]

Thanks for the correction on the tolerances.  I had assumed plus or minus.    This does mean you are completely correct that anywhere within spec is perfect, and given that bucket and shim valve clearances virtually always tighten, setting at the high end is just as perfect as setting at the middle, and is a good practice. 

It's the "virtualy" that setting in the middle takes into account, it's not a certainty.  What causes it to tighten or loosen is another matter, excessive change either way is indicative of a problem and not normal wear.  Worn cam shaft bearings will see all valve clearances rise on that shaft or side for example.

Any engine that needs shims at every valve check would be a concern worth further examination, after the initial full bed in you shouldn't be needing to intervene for 50,000 miles plus.  That doesn't mean don't check them at specified intervals if they are all at the top end though.  That's just asking for early warning of a potentially extremely expensive failure to be missed.  The consequences of the failure of one component will be on the whole engine. Catching it early is a much cheaper and easier fix.  And it's the failure that I see day in, day out, it's either a relatively simple single component fix, whole engine refresh or a full rebuild, and so many of these are entirely avoidable.

Getting back to the op's first post, the valve clearances were all in spec, that is, perfect.  It was good of the shop to mention that some were on the tight side, meaning the next scheduled check should take place on time, and he should be prepared for a possible re-shim at that time.  But that is still only a possibility, not a certainty. 

And Kwackboy, I take it all back, I'd be happy to have you do my valve clearances, and buy a bike off you!

[vstroman]

Just a quick question, this stuff is way beyond my ability to attempt so I'd be taking the bike to a mechanic I trust, my 650 has just over 20,000 miles, never been checked and is running perfect as far as I know,
when should I get the clearances checked? thanks

[Mr Nick]

Just to try to get back to some semblance of agreement on this, which oil & tyres should I use to stop the gap closing.....?
 

[Ian T]

Lost me before the end of page one

[greywolf]

The book says 14,500 miles for the first valve check. It's a good idea to do the first one on time to see where the clearances are as Suzuki seems to like to set the valves somewhere the lower half of the spec. At least my experience on two 650s plus what I've seen reported would seem to indicate that. If somebody else does the job, make sure you get a report on what they found. If no clearances are at minimum, especially exhaust clearances, you can consider extending the interval to the next check. Don't wait on the first one though. You don't know how well the factory did the job.

One thing I've noticed at this site is Kwackboy is one knowledgeable bloke. I wish I had a dealer in my vicinity I could trust the way I would trust him.

[vstroman]

Thanks Greywolf, I'll get them checked this winter.

[kwackboy]

Thanks GW..  .

Is it to late in the thread to say a gap is a gap so be done with it ..? 

[Ian T]

Think so. It going in on Tuesday to an independent chappy. So what ever gap is a gap ?

Cheers

Ian

[Ian T]

Well to bring this epic saga of a gap is a gap to a close I've had me gaps checked, me shims done and me bumps read. In order for clarity:

Gaps were the same as I measured em, so really happy I not turned into a total Fuckwit.

Shims changed to reflect the sensible advice given here.

Bump reading well I failed that given I live in the Midlands and East Yorkshire especially on bank holidays.

So a gap is a gap is gap yeh

Cheers

Ian

[pr]

So if a valve, or multiple valves, are a bit too tight, what could symptoms be that you would notice while riding? Is there some simple way of 'feeling' if it's all normal?

[Hondaman]

None.
The only way is to check them.

Many years ago I had a Yam with 5 valve head. At around 5 k miles, the starting wasn't as sharp as it had been. Someone suggested tight valves - I checked them and all inlets were tight (way out of spec), the middle inlet of the three had no clearance.
All were set to max spec.

I reshimmed those valves 4 times in less than 20k miles, each time to max clearance.

Now interestingly, with correct/max spec clearances the engine sounded very slightly noisy, just a little tickety flutter from the top of the engine, with tight clearances, tge engine ran sweet as a nut and pulled like a train but I knew the starting would soon go 'off' and another valve job was looming!