Richard no problem, I try to steer people in the right direction, (pun
intended).
125's are very sensitive to jets, one size too big and your a backpacker, one
too small, and sqeak! We put a ton of timing in too, lots of oil in the fuel,
a spec of oil in the fuel, we tried everything, and got quick doing it but it
takes time and money!!! I got the stack of pistons to prove it!!! We also
swap pistons every other weekend, and rings once a weekend.
I was always told, lean is mean!!!!
CR
Richard Schmidt <[EMAIL PROTECTED]> wrote:
Chris,
You are correct. Unless Ken messed with the timing, my guess is that it is
just a lean situation.
Also, I did forget to mention the "clean the crankcase" thing. I was
getting a little long in my note and left that off, but it is important.
I don't have a "stack" of melted pistons, just 6 or 7 of them. Most of
them from the Kawasaki, one from the 494. Guess I am a slow learner. You
would think that after a couple, I would get the idea, to lean, to bad !
All caused by lean conditions, for some reason or another.
Richard
----- Original Message -----
From: "Chris Reinhardt"
To:
Sent: Sunday, August 27, 2006 4:56 PM
Subject: Re: [F500] Melted 494 piston question
> Richard I would clarify that a little bit. The top of the piston and plug
deposists are dead givaways for DETONATION!!!! Usually timming, but could
be a lean deto. A temp related sieze you would see the tell tale "4 Corner"
stick meaning the piston expanded evenly all the way around. Lack of lube,
will generally give a score on both skirts, along with blue'd wrist pin
bearing. A lean sieze is usually a melt on the top of the piston closest to
the exhuast port.
> Warning!!!! A bunch of that aluminum that used to be a piston, is now
in the crankcase. I would not even think of just cleaning up the jug and
stuffing a piston in it unless I had a race that day, otherwise flush the
crankcase best you can.
>
> CR
> PS I have a stack of 125 pistons with every type sieze you could
imagine!!!
>
> Richard Schmidt wrote:
> Ken,
>
> I doubt that your piston melt down has to do with high water temp.
Aluminum
> deposits on the spark plug is a sign of a melted piston. Most likely
caused
> by too lean a fuel mixture to that cylinder. Lack of proper lubrication
> could also cause a piston to seize, but this would not cause the top of
the
> piston to melt.
>
> A lean running engine will run hotter and put more energy into the
coolant,
> but this an effect, not the cause.
>
> Do not attempt to rotate your engine any more than you have. This could
> cause more damage. The fix is to disassemble the top end of the engine and
> remove the affected cylinder and piston. Carefully inspect the other
> cylinder walls and piston for damage. It may not be necessary to remove
the
> other cylinder if no damage can be seen to the piston and cylinder walls.
>
> You can easily remove the aluminum welded to the cylinder wall using
common
> hydrochloric acid used for pool maintenance. Be sure to do this outdoors
> and wear a good pair of rubber gloves. Make sure you are up-wind from the
> cylinder and just pore a little at a time in the cylinder. You will get a
> lot of bubbling action. Carefully rinse the cylinder with water and
examine
> it. Use a steel bristle brush to remove any oxidation. If some aluminum
> still remains, repeat. The acid will not harm the steel liner. Be careful
> not to get the acid on the other aluminum parts of the cylinder.
>
> When all the aluminum is gone, inspect the cylinder for scoring. If you
> broke a ring, you may have scoring. Depending on how bad it is, you may
just
> be able to use a hone on the cylinder to remove some of the scoring and
get
> a cross hatch pattern again.
>
> Get a new piston and rings and reassemble. Piece of cake !
>
> As for the fastest way to get going again, replace the engine, most likely
> no more that two hours of work. Of course you have to have a standby
engine.
> If possible, never go to the track without a backup engine. It may seem
> like an extra expense, but if you add up all the expenses of just getting
to
> the track and entry fees, you will soon realize that you will actually
save
> money if you have a back up engine to run on Sunday rather than go home.
>
> Richard
>
>
>
> ----- Original Message -----
> From: "Kenneth Kirkland"
> To:
> Sent: Saturday, August 26, 2006 10:32 PM
> Subject: [F500] Melted 494 piston question
>
>
> > Hello all!!!
> >
> > I'm an F5 newbie running my first season of regionals
> > in the Midwest Division. I've been lurking on the list
> > for a while but haven't had a question to pose yet. My
> > first is a doozy.
> >
> > Apparently, a piston in my 494 melted down due to high
> > water temps during a regional at Hallett on 8/6/06.
> > There are some wonderfully shiny metallic deposits on
> > the spark plug in the left cylinder. The crank will
> > only turn about 45 degrees, with some metal on metal
> > sounds accompanying what little rotation there is.
> >
> > I had hoped to run one more regional before the end of
> > the year to get a national license when I renew my
> > license in early '07. What's the best approach to
> > remedy this situation? Redo the top end? Bolt in an
> > entire rebuilt engine? What symptoms would dictate the
> > need to work on the bottom end?
> >
> >
> > Thanks for any and all assistance,
> > Kenneth Kirkland
> > MiDiv #18
> > www.kirklandracing.com
---------------------------------
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