[ST] Possible bad Triumph valve design

["Mike Benzon" <fast87@xxxxxxxxxxx>]

(Sorry, this is the second posting of this, first one was posted as an
attachment)

I have some distressful news about our Sprint ST's that may or may not be
true. Several
months ago I discovered that my Sprint needed a valve job. I was given a
quote at a
dealership for $1800 to do the job. I had lots of time on hand and a little
distrust in the
dealer, so I brought the bike home and performed a few tests of my own. # 1
cylinder had
zero leak down, # 2 had 30% leakage and # 3 had 100% leakage.

At this point it is only fair to admit that I have 30K miles on my bike and
I haven't
performed a valve clearance check or adjustment.

So, I proceeded to pull off the head and take it to a shop and have a valve
job done. I live
too far from a dealer so I went to an independent shop. The shop owner is a
previous
mechanic for several factory teams such as Yamaha, and Honda at the World
Super Bike
level. I believe what he told me and so I think it is VERY important to pass
this
information along to all of you.

I told the shop at the out set that I was at fault for the problem because
of my lack of
maintenance on the valves. The shop indicated that they doubted I was the
cause of the
problem. How can this be, I asked? They informed me there is a problem well
known
about the valve set up in the Triumph heads world wide. I am leaving name of
shop and
mechanic out of this because I don't want any attention brought to them. So
I will only
refer to them as the shop. The shop tells me that Triumph builds the head
with too weak
of valve springs. This causes the valves to bounce on the seats. The
bouncing causes the
valves to cup where they match up to the valve seats. As this process
continues the valve
sinks into the valve seat, necessitating valve adjustments. I think everyone
knows that the
valves at adjustment time are not loose, they are tight. As the valve
settles into the valve
seat, the clearance disappears and we have to adjust for more clearance. The
shop says all
my valves are badly cupped and they showed them to me, they were badly
cupped. I will
have to replace all my valves.

The springs are too weak, so, we have to either replace them with stronger
springs or
shim them. The shop says the lack of timely adjustments has nothing to do
with the valve
damage. I don't think my valves are an isolated case. At some point, for
those of you who
do a good job of adjusting or having your shop adjust your valves will
eventually discover
the same problem, however, much, much later. The shop says once the valves
seat
themselves there should not be more than ..002mm change in the valve
adjustment over a
30K mile range.

Perhaps Triumph knows the valve are cupping and given proper valve
maintenance they
will function a long time and the issue will never be so obvious.

My shop is researching for information regarding this issue and whether or
not there is a
recommended change for the valve springs. Outside of valve adjustment, I
take very good
care of my bike and I don't mistreat it. I have only participated in one
track day, which is
the only time I have ever approached 9K on the revs and I have never revved
it to the rev
limiter.

I would like to hear any response to this, especially if you have
information that supports
this case.

I am not pressing any recourse from Triumph, my bike is beyond any warranty
and my
lack of valve adjustment would clearly be an issue. So let's not go in that
direction for my
case.

Mike Benzon
Burney CA
'00 Sprint ST


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