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Re: [turbobike] jet kit for turbo carbs

Dave Morrill (david.p.morrill@fairchildsemi.com)
Thu, 15 Apr 1999 08:43:27 -0400

    I have pressurized my carbs on my CBR600 exactly in the way you have
described below.  I would think that by doing this I wont have to mess with
the springs in the CV slides.  Is this what you found?

    What are you using for a fuel pressure regulator, and how many pounds over

    I'm dynoing this Tuesday for the first time, any tips would be helpful.


Christer Johansson wrote:

> Hello George
> I did send a mail about 3 days agoo to this list ,but it seems
> to have vanished!
> Thereīs no secrets in tuning CV carbs for turbo ,just laws of physics.
> You have to pressurize them right, I have a 1/2 inch hose routed from
> the pressure pipe (after the intercooler) to the carbs ,connects beneath
> the membranes ,thus eqalizing the pressure in the carbs and the boost.
> I also have a thin line routed from the pressure pipe to the vent pipes
> on the bowls, this "line" protrudes into the pressure pipe (about halfways)
> facing against incoming air, thus giving dynamic pressure.
> Sort of "force feeding" the main jets. I used 162,5 main jets on the old
> setup.
> But it depends on how this pressurizing turn out, wich mains You will need.
> I know people that has used 130 mains on 300hp bikes.
> I will send You picīs , probably will explain it a bit better.
> I also use stock springs and needles. My bike idles just like a stocker,
> much better than the Efi bikes I have seen. As longs as Your carbs
> are tuned correctly ,there is no advantage in EFI.
> Mark Moisan used 36mm CVīs on his 429hp GSXR.
> The plastic lids on the CVīs can crack if You go wild on the boost (+20psi)
> or get a backfire, I have had no problems though.
> You asked earlier about the data on My old Garrett T03, it was trim60
> A/R ,48 in this size it will support about 270hp . Port the outlet and fit
> the
> biggest possible wastegate valve and it support about 290-300hp.
> There is no idea to use a bigger A/R as the narrow sector is in the
> turbine wheel itself, bigger A/R would only yield more lag.
> You could also separate the wastegate and the turbine and run twin
> exhaust pipes, this would give even less backpressure.
> If You want more power than this You will have to use a bigger turbo
> like the T04E, but then you You will have to use a twin flow exhaust
> housing ,otherwise there will be to much lag.
> Hope this helps / Christer
> george kalogeropoulos skrev:
> > Now what's the secret behind jetting the stock cv carbs with a turbo?!I
> > haven't been able to get some real info on what people are using to do
> > this....is it some kind of jet kit?Who makes the heavier
> > springs,needles,jets.Everyone is saying that these parts where modified
> > to work?Can someone give me some real info about this???This has been
> > tormenting me for the last few nights!My friend says don't bother with
> > carbs.Christer seems to have this system running really well.Will the
> > bike idle properly?
> > Thank guys :)
> >
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