Do you bother with valve clearances?

[EazyDuz]

Seems like one of those maintenance items which are often overlooked when buying used bikes and only an absolutely loved and cherished garage queen ever seems to have the service receipt of a valve job done on the bike.
Having done it myself (with the help of TeflonMike going back several years on my first ever 125 suzuki) it wasnt too hard. But that was a 125. Bigger, more complex machines it can turn into a huge chore and so i've not yet done it on my current bike.
Manual states check and inspect every 7500, I bought the bike with 10,000, no documented valve inspection, and its now on 16000 and still not inspected.
I can hear them, they dont sound clattery and they're not silent either, and the bike runs fine. Is it worth tearing it apart to check? I'm under the assumption that only very tight valves could cause an issue, while loud/clattery valves are a bit safer but obviously should be addressed if the noise is excessive. The valves on mine according to other owners get tighter with mileage, but as I said I can hear them ticking away just fine.
They are the lock nut type at least so no need to mess with shims.
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To shreds you say? Tss tss tss

[stinkwheel]

Depends on the bike.

I used to check them regularly on my GPZ500 and they usually did need adjusting.

I checked them for the first time since it was new on my last VFR750 at 45k miles and they didn't need doing.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Nobby the Bastard]

Not until I need to. The strumpet is on 34k and I'm planning on having a look at some point in the next 10k but shim and bucket are a fucking arse to do so I'll probably take the bike off the road for a week if any need doing because its less hastle to get the train to work than reassemble and then disassemble the cams.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[The Shaggy D.A.]

Only one of my bikes had shims, the CB500. Paid for a full service when I first bought it, it was at 56k and unknown service history. Never checked them after that. All the other bikes have been locknut, usually needed a tweak at some point. Current bike has self adjusting pushrods, so not touched them.
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Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[Bhud]

Yes, I keep them well within spec, religiously.
It also gives me the opportunity to check my cam chain, check that the CCT is doing its job, that the timing marks still line up, etc.

[MCN]

Engine valve wear towards tight or less gap (clearance).
The thing it effects is engine compression. If there is not enough gap due to wear the valve is not able to close perfectly so gas escapes. Not much noise as such. Rattling valves are a more serious matter.
The shimmer valves don't wear as much as older rocker arm types. There is more surface area to carry the load of the cam lobe.
24000 30000 miles is the time to check.
There is a tolerance too if the valve gaps are still sitting the tolerance then leave it till the next interval.
There were scare stories about valves in bikes but they seem to have gone away. 🤣
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Ribenapigeon]

I've never done it on a bike but I remember with old cars when I was younger checking valves. The thing I was never sure of was the use of feeler gauges because they're about "feel". I was never sure whether I was feeling the right gap. Is it too slippy is it too tight is it just right? I never knew what the goldilocks point was.

I was actually considering buying an old XK6 engine of fleabay for a couple of hundred quid so I could do some spannering on it just to see how much of a pain such things are.

[Courier265]

Can't remember the last time I bothered with Valve clearances, my CBF has shims and I've never had them checked, might have them checked at 50K.

As I ride a bike for a living I would notice when the bike isn't running right so then I would think about things like valve clearances and changing air filters.

[Pete.]

Checking clearances is easy if you can get the cover off. No reason not to at least check them at service time. If you find they are fine it costs you not much at all. If they are very tight it'll save you a burnt valve.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[MCN]

The ball bag burster if you find a tight valve on push-rod-less engines is that the job requires the camshaft to be removed. Maybe an engine out task. Bastirt.... But again, those engines do not suffer as much wear some how.
Possibly better valve face and seat design, cooler running better fuel, oil etc.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Nobby the Bastard]

TBH the arsehole isn't the head itself it's removing fairings, tank, radiator etc. just to get at the fucking head.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Easy-X]

[Bhud]

One of those reasons why fairings can be a royal pain in the behind...

Shim arrangements aren't necessarily that difficult to handle though, especially when they're 25mm across and the bike is air-cooled... You just need to find a way to press down the edge of the valve bucket, such as a screw-down tool, to let you pick out the shim. Either that or the folded ziptie down the spark plug hole trick. It depends on the bike. On some very old bikes, there is a gear-driven tachy that needs to be disconnected, and there is no space to get a tool in there, and a lot can go wrong when reinstalling the cams if you have to remove them.

On my XJ600N there are 8 valves, and it takes me about an hour to whip off the tank, airbox, carbs and cam cover, and measure all the clearances. I say about an hour because if anything is a bit close to the limit, the underlying shim may have to come out so you can see what it is and find a suitably-sized new one, if you haven't made a note about it (i.e. if it wasn't put in there by you). Over about 40K (of my) miles, all the shims have been replaced or moved around at least 3 times. If that seems a lot, it's probably a combo of letting the bike get hot, using high revs on every ride and having reconditioned the valves (lapping removed some material) and head once. A fairing coming on or off would add considerably to the time needed for this job... Also you usually have to do it twice: everything comes off to measure and take notes, then everything goes back on, you order your shims, ride around in the meantime, then when they come through the post you install them.

[mentalboy]

[kgm]

I check them as dictated by the manual for both my CG125 and CX500 - both are really easy to get to and are a simple tappet setup.

I skipped the 16k valve checks on my VFR as they're apparently rarely out of spec and mainly because I don't have the vtec tool required, didn't have the time and I was quoted 450+ for a garage to do it. I'll do it at 32k myself probably when I can afford to have the bike off the road for a bit.

[redeem ouzzer]

Personally I’d never own a four stroke with shim valve clearances. Taking the cams out every five minutes is inviting an engine full of muck and worn threads on the cam caps.

I do them every 8k on my 1100 (about double the recommended interval) and every couple of years on my 400 track bike (both screw and locknut).
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Be a REAL MAN!

[EazyDuz]

[ADSrox0r]

Again, depends on the bike. I've never bothered with the VFR (40k on the clock) because it doesn't give me cause to suspect they need attention. And Honda techs are famous for saying they've hardly ever seen them go out of spec, especially the VTEC valves.

Shitty 25 year old Aprilia though? Yeah, an energetic fart on the seat can throw those out a day after you've done the fuckers.
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Current bikes: '08 VFR 800 VTEC(yo) , '07 ZZR1400 Winter hack: '95 Aprilia 650 Pegaso Currently lusting after: RC30

[stinkwheel]

It's no harder to check shimmed tappets and they are (in my experience) less likely to need adjusting.

All bikes are different though. The VFR750 is surprisingly easy to do considering the complexity of the motor. You whip the tank off, unbolt the airbox and the two rocker covers are looking right at you. Even if you need to change a shim, there's no camchain. You just undo the cam caps and the cam lifts right off the top of the gear drive casette.

The GPZ500 was a ballache. It has two coolant pipes which run down through the rocker cover so you need to drain the coolant and replace the o-rings on the pipes (they are garaunteed to leak if you don't). Locknut adjusters though. I used to just check those when I changed the coolant.

My MZ 660 was a piece of piss. It had tappet inspection covers. You just undid a little cap on the rocker cover and the tappet was looking right at you. Needed angled feeler guages though.

The enfield is super simple to check. You don't even need tools since I put a thumb screw on the tappet cover. Remove cover. Ensure push-rods can be rotated but not lifted up and down. Replace cover.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[ADSrox0r]

[stinkwheel]

[Islander]

I check the Ducatis periodically and have had to reshim both of them. Interestingly, both were the vertical exhaust opener. I need to check the R850R this year and I'm going to have to check the Bandit 1200 at some point. Both of those are adjusters on the rocker so should be a doddle.

It's not hard to do, it's just time consuming and a bit if a faff on some bikes.

[Pete.]

[Islander]

[MCN]