Don't apologise for the length of your post, it is very much appreciated
information.
Sam Blumenstein #795
TC wrote:
> Sam,
> I agree ... do it at the PAJ2 as long as you don't have to go extreme
> to get the results you are looking for .. ie: if you hit "reasonable
> limits" which IMHO is a DJ150 on the bottom, (trying to richen) and a
> DJ190 on the top, (trying to lean it out) .. then you should make a
> pilot fuel jet change, (I am not advertising but take a look at the
> jet "comparison" chart if you are doing this with Mikunis .. at ...
> http://www.tcamp30.home.pipeline.com .. look under the "trash" section
> for the chart.
>
> You are trying to avoid making your mixture screws too rich, (which
> are for idle .. a closed throttle pilot mixture job), or your needles
> too rich, (which are for mid-range), to cover "open throttle" pilot
> mixture shortcomings, (which can only be adjusted via the pilot fuel
> and air jets).
>
> Adding more air with the air jets or more fuel with the fuel jet is
> like changing the temperature on a water faucet, (going from hot to
> cold). Then up to a limit ... without regard to the "blend",
> (temperature in this analogy) ... the actual size of jets you are
> using to do this is like adjusting the "volume".
>
> I think that it is also important to note that this "deprived" pilot
> mixture situation is not the case for all setups .. I don't think you
> will find this to be the case on bikes that run open Vboost .. in fact
> it appears to be just the opposite. If you look back at Patrick
> Ahearn's hybrid Stage 7 setup, (122+ RWHP/modified air box) ... he ran
> a very conservative needle setting .. and still had to put a "bigger"
> PAJ2 jet in than the Mikuni 170, (stock), and he was still using the
> stock pilot fuel jets, (37.5), (so he was making his pilot mixture
> leaner ... please correct me if this is wrong Patrick !!), ...
>
> Then Charles .. not too long ago .. running a manual Vboost, (but
> normally open), Stage 7 with individual filters ... He ended up with
> very "open" needle settings but also had to put a "bigger" PAJ2 jet in
> to lean out the pilot mixture to get the results he was looking for,
> (made his pilot mixture leaner).
>
> Annnnd not to write another novel here .. but important to clarify
> this concept ... there was a recent post of dyno results for a great
> Stage 7/pipe setup ... I forget who did it .. but they tried a dyno
> run with the Vboost working normally on one run and open all the time
> on another. The "normal" Vboost run had a bad dip rolling into
> midrange, (just shy of 45K), and the "open all the time" Vboost
> didn't. This supports the concept that an "open" Vboost subsidizes the
> off idle pilot mixture ... and that additional enrichment was not
> necessary. The "normal" Vboost run, (where it was closed at 45K),
> wasn't getting this help and showed the dip because the pilot mixture
> was just to darn lean.
>
> Since Patrick is going to punch me out anyhow for using his research
> ... I think there is one other "secret to life" concept that he
> clarified and is very important to remember to really do it right ...
> Cruising at 3500 RPM and cruising at 6000 RPM is different ... When
> you cruise at 3500 RPM you are running on the pilot circuit only ...
> when you are cruising at 6000 RPM you are running on partially open
> slides, (the needle), "plus" the pilot mixture. These must be adjusted
> to work together or you will get bad performance on one end or the
> other. Soooooo .. if you go too rich on the pilot you are just going
> to be too rich cruising at 55 mph .. if you go too lean on the pilot
> and make it up with the needle .. then you are going to cruise fine at
> 55 mph but be too fat when you are cruising at 90 mph and possibly
> induce a bog when you are rapidly twisting that throttle wide open.
>
> When you hear people say ... "I moved the needles out and the bike is
> getting louder" ... it is getting louder .. and their pipes are
> getting hotter .. because they are getting too rich and they are
> burning the excess fuel in their exhaust pipes ... Like Patrick
> described in his post for the "modified stage 7" ... you need to
> listen for that nice "drone" at 6000 RPM .. and then you know you have
> it right ... Then of course you need to listen at 55 mph/35-38K RPM ..
> whatever ... and make sure you are not hesitating or surging there
> either ... Then you know you have done it right.
>
> A lot of people have tried to explain this on the list ... but the
> "pilot cruising" and the "needle cruising" concept never really
> completely sunk in until I listened to what he was doing with his
> setup ... I am like everyone else .. and important stuff runs off me
> like water on a good wax job .. but this is a very necessary concept
> to grasp and essential to obtaining the very best driveablity and
> performance.
>
> Sorry for another novel Sam ...
> campbell
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