Posted by Tiago on May 1, 2009, 10:45 am
So, my 4 valves are toast. As is the piston, cylinder and clutch and I
strongly suspect my connecting rod gave up working too. It is slightly
loose up-down.
I was talking to a friend and he said that every time valves are
replaced, the valve guide and valve seat must be replaced as well. Of
course the seals will be replaced, however I think guide and seat to
be overkill, but I'm not saving money on this rebuild, I want it back
to where it was when engine was new - if this is ever possible.
Opinions? Any personal experience on this?
thanks,
Tiago
Posted by David Kelly on May 1, 2009, 2:33 pm
Tiago wrote:
>
> I was talking to a friend and he said that every time valves are
> replaced, the valve guide and valve seat must be replaced as well. Of
> course the seals will be replaced, however I think guide and seat to
> be overkill, but I'm not saving money on this rebuild, I want it back
> to where it was when engine was new - if this is ever possible.
> Opinions? Any personal experience on this?
I think "must replace" is too strong of a choice of words. They should
be checked and measured, then a decision made.
In general the difference between a mass produced engine and a good
engine builder is the quality of the seal between valve and valve seat.
A good engine builder will grind a seal much better than the original
factory. So if you only want original good then you need to find an
average wrench to do your valves. :-)
Posted by Tiago Rocha on May 4, 2009, 7:14 am
> Tiago wrote:
> > I was talking to a friend and he said that every time valves are
> > replaced, the valve guide and valve seat must be replaced as well. Of
> > course the seals will be replaced, however I think guide and seat to
> > be overkill, but I'm not saving money on this rebuild, I want it back
> > to where it was when engine was new - if this is ever possible.
> > Opinions? Any personal experience on this?
> I think "must replace" is too strong of a choice of words. They should
> be checked and measured, then a decision made.
I did that. I let the guys who do this for a living check it for me. I
can't risk ruining everything. Valves needed only grinding...
> In general the difference between a mass produced engine and a good
> engine builder is the quality of the seal between valve and valve seat.
> A good engine builder will grind a seal much better than the original
> factory. So if you only want original good then you need to find an
> average wrench to do your valves. :-)
This is interesting. I wonder how the machine shop will perform...
When finished, I'll report back...
As I didn't had enough damage, I accidentally hit the starter button
with the head off and damaged the cam chain and tensioner. More stuff
to buy!
-- T
Posted by jayc on May 4, 2009, 8:58 am
> As I didn't had enough damage, I accidentally hit the starter button
> with the head off and damaged the cam chain and tensioner. More stuff
> to buy!
That's the second person I heard of that did the same thing this
week! Don't you guys know that the first thing you're supposed to do
when tearing into a motor is disconnect the battery? Well, I guess
you do now...
Good luck with the rebuild - hope it comes out rippin'!
JayC
Posted by Tiago Rocha on May 4, 2009, 9:39 am
> That's the second person I heard of that did the same thing this
> week! Don't you guys know that the first thing you're supposed to do
> when tearing into a motor is disconnect the battery? Well, I guess
> you do now...
Or remove the key/ignition wires. I will have to do that anyway to
replace steering bearings... Lately I am making a *lot* of dumb
mistakes. What's wrong with me? At least, the piston was not too
expensive. Up to now, with lapping, overboring and new piston, gasket
and seals, it is at the 180USD mark. Quality (not OEM, though) parts,
I'm not using cheap stuff.
> Good luck with the rebuild - hope it comes out rippin'!
me too! Everybody on the Graduate class races CRFs, DRZs, WRs, EXCs
and the like. I ride a XR. There is only one other XR in this class. I
plan on beating at least a dozen of those guys.
-- T
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> I was talking to a friend and he said that every time valves are
> replaced, the valve guide and valve seat must be replaced as well. Of
> course the seals will be replaced, however I think guide and seat to
> be overkill, but I'm not saving money on this rebuild, I want it back
> to where it was when engine was new - if this is ever possible.
> Opinions? Any personal experience on this?