How do you know if you valves need done?

[Gazz]

Just wondering, for example; if you buy a second hand bike with no service history then you dont know when this will have been done on the bike, and it is quite expensive in terms of servicing goes.

So what are the symptoms are that this is needing done?

And also, what is done in the process?

[hazza]

Entirely dependant upon the bike. Some valves open up and become tappy when they need doing, some close up and get quieter when they need adjusting. Some are the shim type and others are the standard adjustable ones. If you have a bike with no service history, its probably best to asume that nothing has been done and do a full service inc valves. Its not that hard in all honesty. Get a Haynes and get your hands dirty!

Regards

Harry.
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3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[UrbanRacer]

It sounds like a tambourine

[.....]

Measure them?

If it's the locknut type then it's really easy usually.

[Walloper]

In general, engine valve seats and valve faces wear as the engine is used.
Wear in the seats and valves allow the valve stems to be pulled further into the valve guides of the cylinder head.
This has the effect of making the valve clearance/gap less (or closer).
In extreme cases the effect of wear means the valve cannot fully close (due to the stem resting on the cam-follower/lever.
This will cause poor compression.
Poor compression leads to low power, torque and possible difficult starting.
The noise is not always easy to distinguish fro the other shit that goes on inside a motorcycle engine so usually it is best to do a check.
The check normally requires the tank and air-box to be removed which is a pain.
This is why it can cost a wee bit the have the valves checked/adjusted.

Some engine to add cost need to be checked and if adjustment is needed the camshafts have to come out. This can involve engine removal. This can mean mental costs.

Before you buy the bike find out about what it may cost to check and if required, rectify any defect.

If it's an older bike then it's likely there is no trade certs for service (if even that is worth the paper it's scribbled on).

If you are not certain walk, run or drive away.
You could maybe negotiate with the seller for a discount to cover the cost mind. And then everyone is happy.

Buying anything is never cut and dry. If you know anyone who knows about bikes then take them with you.

Use the Internet (bcf) to find out as much as you can about the machine you are interested in. DO not wait until you hand over the Shekels.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[G]

On a lot of bikes it's fairly easy to check them - but ones with shims it's a bit more hassle to actually change them if needing doing.

Usually very easy to do both if it's tappets.

[EazyDuz]

On what kind of bikes do the valves get tighter over use? I would have thought all would get looser over time due to wear.
Anyway, this is what a bike sounds like with loose tappets and/or loose chain tensioner (some bikes have an auto tensioner, others you do at service intervals)

https://www.youtube.com/watch?v=y-ojHNiHUsc

Basic way to know if its the tappets is to put your ear as close to the tappets as you can with the engine running.
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To shreds you say? Tss tss tss

[DrDonnyBrago]

I think when buying, it is fair to assume that ALL used bikes without service history are due a valve clearances check.

[flumpy7]

[Walloper]