Your Dyno run

Paul Landry p_landry at
Sat May 8 20:20:12 PDT 2010

Hey Steve (you should get this message twice, once from me to you and once
from the GPz List, a reply to all from my post should have given you the TO:
address of gpzlist at ).


Excellent info, everyone always talks HP & Torque but other factors like AFR
are often glossed over if mentioned at all.

Honestly, I saw it but did not know if my results where good or bad.  The
shop that did the Dyno run made no comment so I assumed it was at least in
the area of "ok".


If I understand you correctly, what I would need based on what you saw on my
Dyno chart and your experience is a smaller Main Jet, correct?

The benefits of doing this are what specifically, you mentioned gas
consumption and I understand that it would "better" my gas mileage.


I would be very interested in what you find when you Dyno yours and you post
the results.


Thanks for the info..  


Paul W. Landry

 <mailto:P_Landry at> P_Landry at



From: Steve Clark [mailto:clarks at] 
Sent: May-08-10 11:31 AM
To: P_Landry at
Subject: Your Dyno run


Hi Paul - please look at your dyno run and have a look at the AFR (Air Fuel
Ratio)  Ultimitally you want to see a 13.2 or so.  Now this is a wide open
pull on a dyno and besides the hp and tqr readings all we know for sure is
the main jets are to big as the air fuel ratio in in the low 12s and during
a wide open pull you are completely on the main jet for fuel - your getting
to much so the jet is to big.   I see this alot as I work at a small shop
with a dyno.  See it on all the new EFI bikes.  Lean in the lower RPMs and
Rich in the 60 to 100% Throttle position.  Our conspirecy theory is the
manufactures make the fuel maps this way to protect us from ourselves.


Thing is a larger main jet will not change your HP that much but it will
waste gas.  We ride the bikes on the dyno like you might on the road and try
to select the best combination of Idle speed, needle height (and some times
taper) to make sure the bike works well where the customer needs it to.


I would have posted this on the GPZ list but could not find the list with
your post to reply / relate this to.  Feel free to post it.


In about a month I will be putting my GPZ on the Dyno - it will be stock and
I should be able to provide a good example of the set up needed to keep our
bikes starting, performing and eating up highway miles.



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