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When do you know you need them replaced? Noises, performance loss, typical milage, etc

How do you replace them? is it simple after you drop the engine, remove the cams and tappets? Any special tools that you NEED and particular order when replacing the tappets?

Any other jems you've found when doing them would be great

Cheers

Only way you will know if they need replacing is to get the feeler gauges out and check the clearances.

Not 100% sure on replacement, but some bikes require you to take the cams off to get to the shims, others just require the valve pushing down with a tool and then a magnetic tip to take the shim out.

HTH

RobB wrote:Only way you will know if they need replacing is to get the feeler gauges out and check the clearances.

Not 100% sure on replacement, but some bikes require you to take the cams off to get to the shims, others just require the valve pushing down with a tool and then a magnetic tip to take the shim out.

HTH

Cheers mate,

I've just got a sound like woody the wood pecker coming from my engine at about 4,000 rpm. Not sure whether it's normal. But since I shouldn't hear them when they kick it, I'll let it be for now.

check the camchain tensioner for your woody the woodpecker noise. theyre known for it

carsounds_dan wrote:check the camchain tensioner for your woody the woodpecker noise. theyre known for it

That's probably it. just put a new one on and after a few hundred K's it seems to have disappeared. though a new ticking noise seems to have taken it's place. it sounds top endish, but I'll tighten the headers anyway just to be sure.

Cheers

could be the camchain guides as-well or the camchain itself slack.
neither are expensive.
cheers
dan

Vlave shims are easy to change.
You can do it with engine in frame but it is easier with it on the bench. And theres no need to remove camshafts. The rocker will lift and move to one side and out come the shim............a small magnate is useful for this

Turn the engine over and measure each valve clearance if any are out of spec then remove that shim...........measure it and work out what size of shim you need to bring the clearance back into tolerance.

EG if the clearance is too tight you need a smaller shim likewise if the clearance is too loose you need a larger shim.

Be careful you have the engine in the corrrect postion when you measure.

cargo wrote:Vlave shims are easy to change.
You can do it with engine in frame but it is easier with it on the bench. And theres no need to remove camshafts. The rocker will lift and move to one side and out come the shim............a small magnate is useful for this

Turn the engine over and measure each valve clearance if any are out of spec then remove that shim...........measure it and work out what size of shim you need to bring the clearance back into tolerance.

EG if the clearance is too tight you need a smaller shim likewise if the clearance is too loose you need a larger shim.

Be careful you have the engine in the corrrect postion when you measure.

cheers mate, sounds easier than I thought it would be.

When did you have to replace yours? I've done just over 26000 miles

There is a service interval for this in the manual I think.

However for myself I would do this job at the end of every race season. Also if I've lapped in valve seats at some stage its essential.
I would say an engine with 26000 miles on it would be over due a check.

Thing is if valve clearances are wrong then valves are opening too early or closing too late and slowly but surely damage is done to the valve seat..............eventually the seat is so badly damaged that the valve does not seat correctly and this will have a bad effect on performance. Trouble by the time this happens it too late you've done damage.
Of course if valve clearances are to great you get that tappity noise. But there won't be so much noise if clearances are too tight........just valve seat damage..................

IMHO
Looking after valve seats is vital.............use a lead replacment additive in your fuel. I know ZXR400 are designed to run on lead free but hey theres no harm in adding a little insurance.
I use Castrol Valvemaster.............never had to replace valve seats or get them re-cut............. yet !