Valve clearances

[Spanner Man]

Morning all.
I have found that on most shim & bucket engines all clearances tend to close up, this seems to be particularly prevalent on inlet valves, as I seem to shim more inlets than exhausts, on all makes & models.
Valve seat wear, & the valve stem stretching mostly contribute to the clearance lessening, whereas wear on the camshaft bearings, & the bucket & shim itself would contribute to the clearance increasing. On a well maintained engine the former is much more likely.
If a valve clearance is out of tolerance it need correcting period! On an SV where one can remove the camshafts individually, any camshafts that have both clearances within spec I tend to leave alone.
On something such as a ZX6 or 9 which have a one piece bearing which retains both camshafts, one would be daft not to re shim any valves that were virtually at either end of the specified tolerance.
A point of note, Kawasaki sent out a flyer to all dealers in the mid nineties which stated that when shimming valves, shim to the upper end of the specified tolerances, which has always been my preferred option, as for every valve I've seen go over tolerance, I have seen at least fifty go under.
Shims from most nineties Hondas (CB500, CBR6, Fireblade etc) are identical to the SV's, & also come in .025 increments. So if you can't get a Suzuki shim, your local Honda dealer may be able to help.

Cheers.

Originally Posted by Spanner Man

....

Thanks spannerman for your informed (and independent) post, that is just what we needed here

So in conclusion, learned/observed FACT:- gaps do ALL close (unless there is something wrong), also Kawasaki suggested at one point shimming to the larger end of tolerance for this reason.

So back to where we came in, to me if you are buying shims and taking on this (not the most pleasant) job; then why not shim on the bigger gap side of tolerance to increase interval where it needs to be done again??? To my mind, the only time it is worth shimming close is if it is a race engine, where every fraction of a HP maters (that little bit more lift) and where it is in bits so often anyway!!!!!

[rictus01]

selective reading and writing the word FACT aren't by any means supportive, but then you knew that.

All valves don't close over time & wear, no matter how much bold type you use.

Kawasaki's flyer of the mid 90's was sent out because there workshop manuals of that time gave direction to set mid range (as do most current manufacturers).

good bit of misdirection with the races engine part I'll grant you.

[Spanner Man]

Handbag chucking time folks!
I actually said MOST valve clearances reduce over time on a shim & bucket engine, & Kawasakis flyer was sent out for the reason that as MOST clearances close over time it would presumably be better to set them to the max. After all, they build the FECKIN things! (& it's 'their' manuals, & not 'there') MIAOWW!.

The only situation on a healthy engine that would generally cause the clearances to increase, would be an excessive build up of carbon on the valves, due to short journeys, or prolonged idling etc.....What reason do you think a single valve can increase it's clearance? Granted they can, one in fifty are my findings, as I've stated.

I don't think that Blue was miss directing, with his observations regarding racing engines, fact actually!

Cheers.

Originally Posted by Spanner Man

....

I agree, using the term ALL is open to interpretation. By ALL I meant both inlet and exhaust valves gaps will tend to close (if everything else is in order/healthy), but then everyone knew that right as it is what I have been saying all along? I too have had gaps open, but its only because of other problems – normal/healthy running engines I have worked on, the gaps tend to close.

Rictus, your tone lends itself to me thinking you are obviously just spoiling for a (textual) rumble, I don’t really know why?

[rictus01]

Originally Posted by Blue_SV650S

I agree, using the term ALL is open to interpretation. By ALL I meant both inlet and exhaust valves gaps will tend to close (if everything else is in order/healthy), but then everyone knew that right as it is what I have been saying all along? I too have had gaps open, but its only because of other problems – normal/healthy running engines I have worked on, the gaps tend to close.

so ALL ment MOST, glad that's cleared up

Originally Posted by Blue_SV650S

Rictus, your tone lends itself to me thinking you are obviously just spoiling for a (textual) rumble, I don’t really know why?

Just clarity.

Originally Posted by Spanner Man

Handbag chucking time folks!
I actually said MOST valve clearances reduce over time on a shim & bucket engine,

Indeed you did and I'd agree most do.

Originally Posted by Spanner Man;

& Kawasakis flyer was sent out for the reason that as MOST clearances close over time it would presumably be better to set them to the max. After all, they build the FECKIN things!

I doubt there was any presumably about it, I don't know, but normally manufacturer amendments are in response it a problem in the original setup specs which is why they give an acceptable range, it doesn't necessarily mean all (not most ) manufacturers recommend it for all their bikes.

Originally Posted by Spanner Man

(& it's 'their' manuals, & not 'there') MIAOWW!.!

apologies, amendment accepted

Originally Posted by Spanner Man

The only situation on a healthy engine that would generally

the only or generally ?

Originally Posted by Spanner Man

cause the clearances to increase, would be an excessive build up of carbon on the valves, due to short journeys, or prolonged idling etc.....

whilst a carbon built up is indeed a possibility, I wouldn't address it by shimming it out as this is only masking the problem, if the engine looked to be in this condition, if minor I'd use additives or if needed strip it down and clean it properly, but then I'm sure you'd do the same.

Originally Posted by Spanner Man

What reason do you think a single valve can increase it's clearance? Granted they can, one in fifty are my findings, as I've stated.!

I was vexed by this for a while also, however upon investigation (source was a Mclaren engineer) was told the inlet valve train runs at between 150' F - 250' F cooler that the exhaust temperature (which remains predominantly stable), this in turn lead to the same components of either side valve train wearing at different rates, and can result in greater clearance, they call it thermal dynamic wear patten.

having actually seen greater clearances on engine that didn't appear to have any other problems (although a history of fuelling changes could well shed light on it), this seemed more than plausible to me, in these cases I would shim it back to spec.

Originally Posted by Spanner Man

I don't think that Blue was miss directing, with his observations regarding racing engines,

Come on now, race engines are generally perseved to be a high preformace, to that end have a far greater amount of time and effort ( not to mention money) spent on them, you can indeed set tollerances tighter and remove the manfacturing slackness from them, but you also need to up the service schedule to match, I can't see many people stripping the engine after a trip in to work

Originally Posted by Spanner Man

fact actually!

Can't be fact, you haven't used BOLD



Cheers Mark.

Originally Posted by yorkie_chris

You miss my point, I don't really care either way, I've seen clearances open, I've seen them close, all I want to see is them back in the middle of their operating range.
No need to call me a knobber about it.

Exactly, go for the nominal and besides at that age of bike it's not likely of much more wear to the valve seats. After all the more they smack the more they work harden and shouldn't be a problem from hear on after this it's more likely valvetrain wear which will increase gap which is not a danger situation it's when they don't seat (no gap or worse negative gap) that exhaust valves burn.

[Spanner Man]

Morning all.
Oh dear the handbags are flying! Good fun though eh!

Enough of this churlishness, let's all hold hands & agree that MOST valve clearances will close up over time. Hence when shimming it would be wise to set the clearances to the mid way point of the tolerance at least. (I'll still set them nearer the maximum).

I have a suspicion that as petrol has changed considerably over the last 20 years, it has contributed to the fact that inlet valves close up more readily than they used to, for back in the seventies & eighties, indeed it was more common to have to adjust exhaust valves as opposed to inlet valves. But, as I've stated I have found the opposite to be the case over the last 10 years or so.
Still on the subject of petrol, I have found that engines that are run on normal unleaded from one of the major companies, (Esso, Total, etc), suffer less in the way of carbon build up on the valves, than those that are run on cheapo muck from the Supermarkets etc.
I have always used Forte fuel system cleaner on engines that have heavy carbon deposits on the valves. I've seen valve clearances reduce by as much as .07mm after an application, & a good run. I don't think it's available now, as it probably contained something that the greenies managed to get banned.

Comparing race engines to road engines is usually of little relevance,(as is quoting Maclaren engineers) but the point Blue made regarding them is most definitely valid. & of course it wouldn't be practical to strip ones engine down after a trip to work!

Anyway, enough of this points scoring, I'm off to give a troublesome Bandit what for!

Cheers.

P.S. My English is much better that yours Rictus old bean INNIT!!!!

Originally Posted by Spanner Man

...

Just ignore him, read his posts to most people, I tend to think they are generally rude and demeaning, rarely actually THAT helpful.

Thanks for your input - hope you get that bandit tamed!!

[Spanner Man]

Originally Posted by Blue_SV650S

Just ignore him.....

Thanks for your input - hope you get that bandit tamed!!

My sentiment exactly!, then again I usually do that when people can't spell

Bandit already beaten into submission! Now to set it's tappets, & being an engine with screw & locknut adjusters I shall set them to the MIDDLE of the recommended tolerance, as on engines with this type of valvegear clearances can go EITHER way in EQUAL proportions!!!!!!!!!!!!

There's a cue for some Backstreetaintgotafeckincluemate type to sling HIS or HER handbag into the ring, if ever I saw one!

Cheers.

Spiffing fun this cyber banter isn't it?