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Subject Author Date
Looking for valve advice Kirby Roy 06-08-2007
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Posted by Kirby Roy on June 8, 2007, 7:38 pm
Hi. I have a 2000 Honda 600 F4 and the valves are starting to make noise.
16,000 KM on it so it's time to check them. The specs are .2mm intake and
.28mm exhaust both are + or _
.03mm. To make the story short all the exhaust valves measure .154mm. This
seems backwards to me. Should
the gap not be getting bigger due to carbon build up, or is this someting
thats done at the factory
to account for breaking the motor in.
It,s overhead valves and it,s not the cam chain tesioner (dun it twice so
far). I just want to be sure
Im not thinking backwards because I have it torn down and I have to go and
buy the shims.
Can someone shed some more light?
Thanks for reading.

Kirby



Posted by Rob Kleinschmidt on June 8, 2007, 7:50 pm
> Hi. I have a 2000 Honda 600 F4 and the valves are starting to make noise.
> 16,000 KM on it so it's time to check them. The specs are .2mm intake and
> .28mm exhaust both are + or _
> .03mm. To make the story short all the exhaust valves measure .154mm. This
> seems backwards to me. Should
> the gap not be getting bigger due to carbon build up, or is this someting
> thats done at the factory
> to account for breaking the motor in.
> It,s overhead valves and it,s not the cam chain tesioner (dun it twice so
> far). I just want to be sure
> Im not thinking backwards because I have it torn down and I have to go and
> buy the shims.
> Can someone shed some more light?

Valves tightening up is normal. The seats can recede a little.


Posted by Albrecht via MotorcycleKB.com on June 8, 2007, 9:41 pm
Kirby Roy wrote:
>The specs are .2mm intake and .28mm exhaust both are + or _
>.03mm. To make the story short all the exhaust valves measure .154mm.

How did you measure the clearances? Are you sure that the tappet was near the
heel of the cam lobe when you checked the clearance? Why did the valves sink
into the seats so quickly?

0.31mm = .012"

0.28mm = .011"

0.25mm = .0098"

0.154mm = .006" ----That's really tight. I would have re-shimmed for sure
when the clearance got down to .009" on the exhaust valves?

The very first time I checked valve clearances with a set of metric feeler
gauges, I spent about 4 hours
adjusting and readjusting the screws before I figured out that metric feeler
gauges were less than half a thousandth of an inch apart.

Then I started using American feeler gauges.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200706/1


Posted by Dave H. on June 9, 2007, 9:02 am

"Kirby Roy" wrote...
> Hi. I have a 2000 Honda 600 F4 and the valves are starting to make noise.
> 16,000 KM on it so it's time to check them. The specs are .2mm intake and
> .28mm exhaust both are + or _
> .03mm. To make the story short all the exhaust valves measure .154mm. This
> seems backwards to me. Should
> the gap not be getting bigger due to carbon build up, or is this someting
> thats done at the factory
> to account for breaking the motor in.
> It,s overhead valves and it,s not the cam chain tesioner (dun it twice so
> far). I just want to be sure
> Im not thinking backwards because I have it torn down and I have to go and
> buy the shims.
> Can someone shed some more light?
> Thanks for reading.
>

It's pretty normal for the clearances to tighten up, a number of factors are
responsible, particularly erosion of the valve heads and seats as "modern"
petrol doesn't have the lead that used to lubricate them[1]. I'd be checking
that the clearances you've measured are correct (cams set as per the
workshop manual so that the heel bears on the gauge), and that the gauges
are cleaner than a very clean thing, etc.

--
Dave H.
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader

[1] Preferring to swap tiny amounts of brain-damaging lead for high levels
of carcinogenic benzene...



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