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#Post#: 2117--------------------------------------------------
Noisy valve gear
By: banquo Date: August 6, 2017, 5:11 pm
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Since reverting to the stock silencer, it's become increasingly
obvious that my valve gear has become far noisier than it should
be.
If you imagine setting the clearance to 2mm instead of 0.2mm,
you'll get some idea of what it sounds like. Or a few dozen
dwarves with heavy hammers.
I tried reverting to the narrower valve clearances, but no
difference, so it looks like the head will need to come off for
investigation.
Anyone have any ideas on the most likely issue?
I've considered a sticking valve being hammered by the rocker
arm (I don't have the extra oil feed, and the inlet looks pretty
dry) or a worn rocker arm, causing a false clearance reading
(although rocking the arm after setting suggests there is no
'false' clearance.
Suggestions from anyone who has experienced the same would be
welcome!
#Post#: 2118--------------------------------------------------
Re: Noisy valve gear
By: Kater Date: August 7, 2017, 11:02 am
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Hello Jake,
It's not good to hear about your problems, it doesn't sound
good. Here my thoughts about it:
I have never heard about rocker lever problems, only of very few
broken -
I don't know how many kilometres the engine has, but the valve
guides are poor quality and worn out after short time and a
valve seat can be loose- this can make the noise.
Hopefully you have not a worn out crankshaft bearing, if the mud
chamber is filled up you have no more lubrication...
I would open the engine and overhaul it.
If it's the head and you need immediately one I can help you
with a regenerated one with double ignition, lighter valves, new
seats and sealed guides, the same I use at my NFs.
Good luck
#Post#: 2119--------------------------------------------------
Re: Noisy valve gear
By: banquo Date: August 7, 2017, 12:39 pm
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Thanks Kater; someone on the Facebook group reported the valve
wearing a groove into the face of the rocker, which apparently
is not hardened. The engine has done only 21,000 km, although of
course I can't be sure if it was built with all-new parts. I'll
pull the head off and take a look. I did buy a spare head years
ago. Apparently the owner had new unleaded seats fitted, but his
bike was stolen before he fitted it. Thanks a lot for your
offer. If you would consider selling the modified head, I'd
still be interested, as I would like the modifications that you
mentioned!
#Post#: 2840--------------------------------------------------
Re: Noisy valve gear
By: Mikec Date: July 16, 2020, 12:23 pm
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Hi, my Military NF has now has 17000km plus on the odo. I’ve
ridden it it for 15000 Of those and enjoyed them all. It has
always had noisy valve gear. It makes a “clacking” noise, most
noticeable at tick over. If I operate the valve lifter very
gently, so that I can just feel the rocker operating, the noise
goes quiet. I’ve had the head refurbished by the Cylinder Head
Shop, with new guides and lead free exhaust seat fitted. I’ve
replaced the camshaft bushes and the rocker spindle bushes ,
although none of them were badly worn. The cams and followers
look perfect. The rocker tips look fine, with no wear groove. I
use 0.15 exhaust and 0.1 inlet clearance. Any thoughts on a
possible cure? It would be nice to ride without earplugs.
#Post#: 2841--------------------------------------------------
Re: Noisy valve gear
By: banquo Date: July 17, 2020, 3:19 am
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Noisy valve gear isn't unusual, and characteristic f even a new
engine. With all alloy cnstruction, and a head stuck out the
front, the valve gear noise is more prominent than on engines
where the head is buried under a tank.
If you have had the head refurbished, and the valve guides
aren't worn, then you could simply be hearing the normal
clatter.
There are two completely different valve clearances recommended
by the factory, dependent on whether you read the Rider's
Handbook or the Workshop Manual.
Handbook says 0.05mm and 0.1mm (0.002" and 0.004") and Manual is
double that at 0.1mm and 0.2mm.
Clearly, the wider clearance is noisier, but, arguably, it's
also safer. I have experienced mine closing up after a long
climb on the narrow clearances, and loss of compression, which
would have led to valve burn had I left it there, so I now run
the wider clearances.
Other have said they run the narrow clearances with no issues,
and it's definitely a lot quieter.
If yours is most noticable at tickover, then there's probably
nothing wrong (when my rocker was worn, it got much worse at
higher rpm), although of course it's impossible to tell without
actually hearing it. I assume you have checked that the springs
and shims on the rocker arms are on the correct ends when you
had it all apart, although I'm not sure that would have any
great effect. Also assume you're measuring the clearances at the
valves, and not at the adjusters.
When you have checked everything and found nothing wrong,
there's a good chance that there's nothing wrong.
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