Posted by I_am_Tosk on June 27, 2011, 9:44 pm
So, me and the mouse did our first valve shims last week. It was easy
really compared to the horror stories I have heard in the past. Anyway,
we did the job and the bike was awesome for a few days. A week later and
we have put 4.2 hours on the engine clock and the same valve is tight
(zeroed out) already. I am assuming this valve is stretching? Can I
replace the valve and have just that one seated if the others are ok? Is
there something else I should be looking for when I take it apart?
Thanks in advance, Scotty RMR.
--
Team Rowdy Mouse, Banned from the Mall for life!
Posted by Volker Bartheld on June 28, 2011, 2:22 am
Hi!
On Mon, 27 Jun 2011 21:44:17 -0400, I_am_Tosk wrote:
> A week later and we have put 4.2 hours on the engine clock and the same
> valve is tight (zeroed out) already. I am assuming this valve is
> stretching?
Is it a titanium valve? Those have a pretty shallow hardening layer on them
and once this is gone, the valve melts away. Another issue could be the
valve seat but unlikely. You can either replace the valves by $$$ original
ones or buy a CroMo replacement set from Kibblewhite if you can afford to
waste a few overrev-RPMs and have a slighty less responsive engine. Steel
valves last a lot longer but you need different valve springs to run them.
> Can I replace the valve and have just that one seated if the others are ok?
Jup. But chances are that the bike is due for a complete valve job as the
other valves might fail soon, too.
> Is there something else I should be looking for when I take it apart?
Coal deposits. Stretched cam chain. Damaged camshaft (and bearings).
Cracked/worn piston. Scratched cylinder. Worn big end bearing/conrod (any
noticeable lateral freeplay is too much). Warped cylinder head surface
(where the gasket sits).
If I were you, I would at least change piston/oil ring(s) and have a look
at the wrist pin, since you anyhow have to take off the cylinder.
Good luck!
Volker
--
@: I N F O at B A R T H E L D dot N E T
3W: www.bartheld.net
Posted by Wudsracer on June 28, 2011, 4:18 pm
((((((((((((((((((((((((((((((((((((((((((((((((((((())))))))))))))))))))))))))))))))))))))))))))))))))))
>On Tue, 28 Jun 2011 08:22:04 +0200, Volker Bartheld wrote:
>Hi!
>On Mon, 27 Jun 2011 21:44:17 -0400, I_am_Tosk wrote:
>> A week later and we have put 4.2 hours on the engine clock and the same
>> valve is tight (zeroed out) already. I am assuming this valve is
>> stretching?
>Is it a titanium valve? Those have a pretty shallow hardening layer on them
>and once this is gone, the valve melts away. Another issue could be the
>valve seat but unlikely. You can either replace the valves by $$$ original
>ones or buy a CroMo replacement set from Kibblewhite if you can afford to
>waste a few overrev-RPMs and have a slighty less responsive engine. Steel
>valves last a lot longer but you need different valve springs to run them.
>> Can I replace the valve and have just that one seated if the others are ok?
>Jup. But chances are that the bike is due for a complete valve job as the
>other valves might fail soon, too.
>> Is there something else I should be looking for when I take it apart?
>Coal deposits. Stretched cam chain. Damaged camshaft (and bearings).
>Cracked/worn piston. Scratched cylinder. Worn big end bearing/conrod (any
>noticeable lateral freeplay is too much). Warped cylinder head surface
>(where the gasket sits).
>If I were you, I would at least change piston/oil ring(s) and have a look
>at the wrist pin, since you anyhow have to take off the cylinder.
>
>Good luck!
>Volker
****************************************************************************
Yep, what Volker said. It's most likely either the valve's seating
surface, or the valve seat itself. Wear equals less valve clearance.
Good Wrenching to You!
Jim
Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF
"You can avoid reality, but you cannot avoid
the consequences of avoiding reality."
Posted by Scrape on June 28, 2011, 9:33 pm
>
> So, me and the mouse did our first valve shims last week. It was easy
> really compared to the horror stories I have heard in the past. Anyway,
> we did the job and the bike was awesome for a few days. A week later and
> we have put 4.2 hours on the engine clock and the same valve is tight
> (zeroed out) already. I am assuming this valve is stretching? Can I
> replace the valve and have just that one seated if the others are ok? Is
> there something else I should be looking for when I take it apart?
> Thanks in advance, Scotty RMR.
I'd look at the valve seats. I know Honda had a problem with them in the
past, but I thought that had been corrected.
Can't remember what bike you've got.
Posted by I_am_Tosk on June 29, 2011, 10:11 am
nothanks@domain.com says...
>
>
> >
> > So, me and the mouse did our first valve shims last week. It was easy
> > really compared to the horror stories I have heard in the past. Anyway,
> > we did the job and the bike was awesome for a few days. A week later and
> > we have put 4.2 hours on the engine clock and the same valve is tight
> > (zeroed out) already. I am assuming this valve is stretching? Can I
> > replace the valve and have just that one seated if the others are ok? Is
> > there something else I should be looking for when I take it apart?
> > Thanks in advance, Scotty RMR.
>
>
> I'd look at the valve seats. I know Honda had a problem with them in the
> past, but I thought that had been corrected.
>
> Can't remember what bike you've got.
2009 RM-Z250 I am pulling the head off today;) Wish me luck!
--
Team Rowdy Mouse, Banned from the Mall for life!
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> valve is tight (zeroed out) already. I am assuming this valve is
> stretching?