[Diy_efi] Estimation of spark advance

[Bruce]

----- Original Message -----
From: "William Shurvinton" <shurvinton at orange.net>
Subject: Re: [Diy_efi] Estimation of spark advance
> Don't worry about your English, as mein Deutsch is nicht gut, but my Br=
uce
> is getting much better and i can usually translate him into European :-=
)

Hmmmm,

> Can't vouch for Perry, but Bruce has built and tuned an awful lot of
engines
> so has something guys like me lack: experience. Someone somewhere once
wrote
> that optimum spark tuning is up to the edge of knock and back off 2=B0.=
 So
> that then becomes accepted wisdom, without dyno data to really back it =
up.

One source of the 2d is some of the stuff I've typed up, ie tuningtips.  =
If
your going for close to absolute max HP but want to run a GMECM, then you
want to keep from triggering the K/S, and a 2d margin (if the fuel is rig=
ht)
seems to be a safe figure.

> And whilst it is probably a very good rule of thumb for racing engines
that
> get rebuilt every few 100km it may not be the best compromise for stree=
t
> use.
> Your bike is not a fireblade/hyabusa and therefore you are probably mor=
e
> after reliability than the last HP. You want good manners when you ride=
 it
> etc. So the optimum spark curve for power may not be what you are after.
> Also if you are flying close to the wind it helps to have a guaranteed
fuel
> that is always the same (I read that so it may be wrong, but makes sens=
e).
> Was that about right Bruce?

Yep
Bruce
>
> Bill


> From: Carsten Beth <Carsten.Beth at Informatik.Uni-Oldenburg.DE>
> > > Motorcycle
> > > (touring) is going to be conservative, tune wise, an increase in
timing,
> > > might just get you some galled rings in stop and go traffic.
 > What do you mean with _conservative_? Do you mean it's better to give
> > less advance? Perry Harrington writes in the same thread something ab=
out
2=B0
> > less than the point where the engine begins to ping. Would you give l=
ess
than
> > 2=B0? And (sorry, my english isn't really good, how you surely notice=
d)
what
> > do you mean with galled rings?
> > Carsten



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