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The Mikuni HSR's are great carbs, pretty much set it and forget it unless you
change altitude a bunch.
Then it's just the main jet. I used them for 3 seasons until I developed a head
that out flowed the stock intake manifold.
I did all sorts of welding and reshaping to the intake and just didn't get what
I wanted out of it so I went to a pair of DCOE's on Cannon manifolds. I first
tried the TWM manifold from Pierce and after some attempted fittings I declared
it a piece of junk and went with the Cannon intake. ( Thanks Tony for that bit
of advice )
Long story short, Mikuni HSR carbs are great but the manifolds will only flow
some much.
jim g
> On October 18, 2018 at 12:49 AM "van.mulders.marcel--- via Fot"
> <fot@autox.team.net> wrote:
>
> -"...hitting a wall at that point..." : is it possible this is rather
> pointing to the camshaft than to the SU's? If it are the carburettors, maybe
> the power would decrease more gradually above 6500 rpm.
> -In general one choke per cylinder is better, and 2 Webers 40 DCOE isn't
> overkill I think
> - what about trying HS6 SU's on your actual manifold?
> At what maximum rpm is your engine still reliable?
> Marcel
>
>
> ---------------------------------------------
> Van: "fot" <fot@autox.team.net>
> Aan: "fot" <fot@autox.team.net>
> Verzonden: Woensdag 17 oktober 2018 15:49:45
> Onderwerp: [Fot] Weber vs Mikuni
>
> I'm looking into switching out my twin HS4s on the 1296 race engine to
> either Weber or Mukinis. I know this has been done for years and I'd like to
> get close the best set up out of the gate.
>
> I don't think the SUs are up to the task of moving enough air with the
> new ported head and Stahl header. I've worked on the SUs and gotten them to
> finally deliver a good AFR , 12.6, at 6500 RPM under load but I seem to hit a
> wall (figuratively) at that point. I suspect that the openings just aren't
> big enough to deliver the mass of air required. (spreadsheet or other flow
> calculator link appreciated)
> Biggest gate I suspect is the intake valve, 1 3/8" head (~35mm) HS4 is
> ~38mm at best.
>
> Recommendations? I've seen all these setups at the track, each with
> pluses, minuses and overkill cause it looks cool.
>
> One weber DCOE 40 or 2? what jets, tubes etc for a starting point? Best
> manifold?
>
> 2 or 4 Mikuni 40? jet size?
>
> thanks
> mike
>
> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
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>
> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
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<!DOCTYPE html>
<html><head>
<meta charset=3D"UTF-8">
</head><body><p style=3D"font-size: 12pt; font-family: helvetica, arial, sa=
ns-serif; color: rgb(51, 51, 51);">The Mikuni HSR's are great carbs, pr=
etty much set it and forget it unless you change altitude a bunch.</p><p st=
yle=3D"font-size: 12pt; font-family: helvetica, arial, sans-serif; color: r=
gb(51, 51, 51);">Then it's just the main jet. I used them for 3 seasons=
until I developed a head that out flowed the stock intake manifold.</p><p =
style=3D"font-size: 12pt; font-family: helvetica, arial, sans-serif; color:=
rgb(51, 51, 51);">I did all sorts of welding and reshaping to the intake a=
nd just didn't get what I wanted out of it so I went to a pair of DCOE&=
#39;s on Cannon manifolds. I first tried the TWM manifold from Pierce and a=
fter some attempted fittings I declared it a piece of junk and went with th=
e Cannon intake. ( Thanks Tony for that bit of advice )</p><p style=3D"font=
-size: 12pt; font-family: helvetica, arial, sans-serif; color: rgb(51, 51, =
51);">Long story short, Mikuni HSR carbs are great but the manifolds will o=
nly flow some much.</p><p style=3D"font-size: 12pt; font-family: helvetica,=
arial, sans-serif; color: rgb(51, 51, 51);">jim g</p><blockquote type=3D"c=
ite">On October 18, 2018 at 12:49 AM "van.mulders.marcel--- via Fot"=
; <fot@autox.team.net> wrote: <br> <br><div style=3D"font-family: V=
erdana, Arial, Helvetica, sans-serif; font-size: 10pt; color: #000000;"><di=
v>-"...hitting a wall at that point..." : is it possible this is ra=
ther pointing to the camshaft than to the SU's? If it are the carburett=
ors, maybe the power would decrease more gradually above 6500 rpm.</div><di=
v>-In general one choke per cylinder is better, and 2 Webers 40 DCOE isn=
9;t overkill I think</div><div>- what about trying HS6 SU's on your act=
ual manifold?</div><div>At what maximum rpm is your engine still reliable?<=
/div><div>Marcel</div><div><br></div><hr id=3D"ox-1082612c44-zwchr"><div><s=
trong>Van: </strong>"fot" <fot@autox.team.net> <br> <strong=
>Aan: </strong>"fot" <fot@autox.team.net> <br> <strong>Verz=
onden: </strong>Woensdag 17 oktober 2018 15:49:45 <br> <strong>Onderwerp: <=
/strong>[Fot] Weber vs Mikuni <br></div><br><div><div dir=3D"ltr"><div>I=
9;m looking into switching out my twin HS4s on the 1296 race engine to eith=
er Weber or Mukinis. I know this has been done for years and I'd like t=
o get close the best set up out of the gate. <br></div><br><div>I don't=
think the SUs are up to the task of moving enough air with the new ported =
head and Stahl header. I've worked on the SUs and gotten them to finall=
y deliver a good AFR , 12.6, at 6500 RPM under load but I seem to hit a wal=
l (figuratively) at that point. I suspect that the openings just aren't=
big enough to deliver the mass of air required. (spreadsheet or other flow=
calculator link appreciated) <br></div><div>Biggest gate I suspect is the =
intake valve, 1 3/8" head (~35mm) HS4 is ~38mm at best. <br></div><br><=
div>Recommendations? I've seen all these setups at the track, each with=
pluses, minuses and overkill cause it looks cool. <br></div><br><div>One w=
eber DCOE 40 or 2? what jets, tubes etc for a starting point? Best manifold=
? <br></div><br><div>2 or 4 Mikuni 40? jet size?</div><br><div>thanks</div>=
<div>mike <br></div></div><br>_____________________________________________=
__ <br>fot@autox.team.net <br> <br>http://www.fot-racing.com <br> <br>Donat=
e: http://www.team.net/donate.html <br>Archive: http://www.team.net/piperma=
il/fot <br>Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/va=
n.mulders.marcel@telenet.be <br></div></div></blockquote><p style=3D"font-s=
ize: 12pt; font-family: helvetica,arial,sans-serif; color: #333333;" class=
=3D"default-style"><br> </p><blockquote type=3D"cite">________________=
_______________________________ <br>fot@autox.team.net <br> <br>http://www.=
fot-racing.com <br> <br>Donate: http://www.team.net/donate.html <br>Archive=
: http://www.team.net/pipermail/fot <br>Unsubscribe/Manage: http://autox.te=
am.net/mailman/options/fot/toodamnfunky@comcast.net <br> <br> <br></blockqu=
ote><p style=3D"font-size: 12pt; font-family: helvetica,arial,sans-serif; c=
olor: #333333;" class=3D"default-style"><br> </p></body></html>
=20
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