How can I tell when valve clearances need doing? >Updated

dabigginger · Crazy Courier Joined: 28 Oct 2006 Karma :

How can I tell when the valve clearances need doing? On my CB500 work hack, the service schedule is every 16,000 miles. Currently, it's on 21,000. Now, I'm not sure if the valve clearances were checked at 16,000 (I bought it at 17,500). I've just started to notice a slight top end rattle that's noticeable from about 6000rpm and above. Now, I'm not 100% sure if this is something that's always been there and I've just started noticing it, or if the sound has just started happening recently.

Is this top end noise a sign of valve clearances need doing? Whilst I'm on the subject, I'm considering checking this myself and changing the shims where needed. Is it fairly easy to do? I'm fairly mechanically capable - I've stripped my car down and rebuilt it etc. I'm no expert, but I'm not afraid to learn.

toolhonda · Borekit Bruiser Joined: 10 Feb 2008 Karma :

The valves are at the top of the engine.
When the valve clearance gets to big (due to mechanical wear) they will eventually become noisy (clatter clatter). This means they need adjustment.

Its relatively easy to check the valve clearance.
Adjusting them is much harder since its shims (but possible).

Some honda mechanics tell me they often do not need adjusting at 16,000 miles so I am not convinced yours do.
So first easy job is to check the clearance yourself.

The Workshop / Service manual is in this forum just look at the 1st post which is Sticky

The Honda CB500 (and CBF500) owners club is at
https://groups.msn.com/cb500club

dabigginger · Crazy Courier Joined: 28 Oct 2006 Karma :

Thanks for the handy links - Karma

given!

However...

I have just found what is probably causing it to be a little rattly (I think it's only when it's warm). The oil is only just registering on the dipstick.

That won't help...

Me---> Embarassed

Why do I always jump to the worst conclusions first. I'll pick up some oil tomorrow and see what it's like on Friday.

toolhonda · Borekit Bruiser Joined: 10 Feb 2008 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

generally your clearances get tighter with age not looser,
your bike will start to run like a bag of nails,
it takes 10 mins to check the clearances,
plus 1/2 hour if you have to pop the shims out to figure what sizes you need to order,
im guessing the cb500 has shims and not a tappet and lock nut
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stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

very easily,
loosen the lock nut then screw in the tappet untill the clearance is right, then tighten the lock nut, and recheck.
and thats it. far easier than shims, but you have to check them more often
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

dabigginger · Crazy Courier Joined: 28 Oct 2006 Karma :

Well, I took it apart today to give it a shot. They're all too tight Evil or Very Mad

All of the exhaust valves are roughly around 0.05mm too tight outside of the tolerances as are the inlets. It was really easy to get to the cam cover!

-Tank off
-Drain coolant
-Thermostat off
-Fairing off
-Cam cover off

I don't feel too confident re-shimming it, so my local bike garage are going to pick the bike up for me and sort it out. Still, at least I've saved a bit of money taking it all apart!

Thanks for the help!

toolhonda · Borekit Bruiser Joined: 10 Feb 2008 Karma :

Glad to be of help.

Please post what happens when you get the bike back.

dabigginger · Crazy Courier Joined: 28 Oct 2006 Karma :

I was borrowing a set of imperial feeler gauges from a garage down the road that does a lot of American cars, so I couldn't be 100% accurate with what I was doing, but I was hoping it would tell me if my clearances were within the correct ballpark.

Anyway, the day after the bike garage picked the bike up, they called to let me know they didn't need doing! They only charged about £10 to check them for me and £30 to pick the bike up and deliver it back home (quite reasonable considering they're around 10 miles away - a taxi probably wouldn't have been much different)!

Anyway, I finished off servicing it, new coolant, oil etc. and it's as good as new! Thanks for all of the help and info!

toolhonda · Borekit Bruiser Joined: 10 Feb 2008 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Metric or imperial makes no difference since you are working to a tolerance. Most manuals quote both imp and metric.

0.1mm is 4 thousandths (or near enough makes no difference for this application) so it's not had to work out.
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