valve adjustment
- Thread starter Ish
- Start date
How many miles? They get tighter as the shims wear
EDIT: im guessing you'd get valve seat damage from them smashing into valve seats more as they get tighter? and difficulty starting
I get mild top end rattle but mostly the rattles are coming from the clutch basket and a bit from cam chain tensioner,starting and power wise its still good
EDIT: im guessing you'd get valve seat damage from them smashing into valve seats more as they get tighter? and difficulty starting
I get mild top end rattle but mostly the rattles are coming from the clutch basket and a bit from cam chain tensioner,starting and power wise its still good
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Soldato
- Joined
- 5 Jun 2003
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- 8,732
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- sawley/ long eaton
if the shims are worn the engine will rattle as there is more gap
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Valves clearances can open up from wear on the cams and followers (fairly rare on modern Japanese machines) which makes the top end sound noisy. Sustained use with clearances that are significantly too wide can cause damage to the cams lobes and lifters.
More often the clearances close up due to valve seat wear, which can cause poor starting and idling, a drop of in performance and ultimately burnt out valves.
The clearances can be below the service limit without these symptoms being noticeable however, which is why the manufacturers suggest they are checked at a particular interval. Checking them is usually not too difficult to do, though changing shims can be quite an involved job.
More often the clearances close up due to valve seat wear, which can cause poor starting and idling, a drop of in performance and ultimately burnt out valves.
The clearances can be below the service limit without these symptoms being noticeable however, which is why the manufacturers suggest they are checked at a particular interval. Checking them is usually not too difficult to do, though changing shims can be quite an involved job.
Someone came into our service department today asking how much it'd cost for a service that included new belts and valve clearances checked on an 848 evo and was shocked to hear it was around a grand. Just wouldn't accept it's a big job and claimed he'd been quoted £240 elsewhere. The Ducati service times poster on display shows clearly Ducati think it's 8.5 hours for that service and they base their timings on someone at their factory with all their tools laid out ready on new machines that shouldn't have anything else cropping up. He didn't book it in.
main dealers are always expensive,i got quoted around £400 but he said it depends on how long it takes
I would have though a ducati would be easier being a v twin,the heads/valves are easier to get to
(its a pity the op didn't have an f model zx6r,they have hydraulic cam lifters and need no adjustment,ever)
I would have though a ducati would be easier being a v twin,the heads/valves are easier to get to
(its a pity the op didn't have an f model zx6r,they have hydraulic cam lifters and need no adjustment,ever)
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I'm surprised people think the hardened steel shims are a wear and tear item, especially when most of them live under the valve bucket - contact being between the cam lobe and bucket rather than cam to shim.
But agree with posts that over time clearances can get tighter as valves/seats wear and the valve sits further into the cylinder head - will lead to valves staying open and starting problems eventually.
Been there long time back with an FZR600 which needed clearances doing before reaching the specified interval when they should have been checked. Bike got harder and harder to start, eventually carried out a compression test which highlighted things were not as they should have been.
On the other hand I then had an FZR400RR which ran just fine and by the time it got to the service mileage for checking the clearances around 18-20,000 miles maybe 1 or 2 needed fine adjustment at most.
For older stuff with rocker arms, screw/locknut adjusters etc they tend to get more rattly as the clearances open up.
But agree with posts that over time clearances can get tighter as valves/seats wear and the valve sits further into the cylinder head - will lead to valves staying open and starting problems eventually.
Been there long time back with an FZR600 which needed clearances doing before reaching the specified interval when they should have been checked. Bike got harder and harder to start, eventually carried out a compression test which highlighted things were not as they should have been.
On the other hand I then had an FZR400RR which ran just fine and by the time it got to the service mileage for checking the clearances around 18-20,000 miles maybe 1 or 2 needed fine adjustment at most.
For older stuff with rocker arms, screw/locknut adjusters etc they tend to get more rattly as the clearances open up.
Can you elaborate? I've noticed my starter motor seems to struggle sometimes. I think this could be due on the bike as well
The valves won't let as much fuel air mixture into the cylinder so won't ignite do well,same as unbalanced carbs
It's usually something more simple rather than valve clearances,difficulty starting
It's usually something more simple rather than valve clearances,difficulty starting
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My bike has just hit 22k and it's never had them checked/adjusted.
I'm going to book it in at a for 2 weeks time so will let you know how much it costs!
I had mine done at 18k,I forget the price back then though,now I'm on nearly 63k with no checks since
I've also read about a gsxr1000 hitting 100k and when they checked they were still in spec,idk how true it is
It seems the first one or two checks,adjustments are more important
I've also read about a gsxr1000 hitting 100k and when they checked they were still in spec,idk how true it is
It seems the first one or two checks,adjustments are more important
The valves smash into the seat harder if the clearances have opened up, since the follower meets or leaves the acceleration ramp on the lobe too late (opening) or early (closing). This puts more stress on the entire valve train. Tight clearances means sluggish opening of the valves (hurts performance), and eventually lack of sealing (difficult starting, poor idle).
On modern DOHC engines they will almost always close up through valve seat wear if the engine has been otherwise correctly looked after. Some Chinese stuff with chocolate cams & followers can open up, as will an engine that been neglected (run low on oil, or oil change intervals ignored).
Ducati's have desmodromic valve actuation, so there are two clearances to be set per valve (one for opening and one for closing). Access is also very limited.
