more on MPG & carb settings
Steve Northrop
blackgpz at rochester.rr.com
Tue Jan 15 14:57:11 PST 2008
Bill, do you know what brand jet kit? It's important for the main jet
size. Do you still have the stock airbox or pods? If he put in what I think
he put in, NONE of which is available in a standard jet kit for the GPZ, you
are very, very, very rich. I'm surprised Hugo Chavez hasn't sent you a
personal thank you note. The 35 slow refers to a #35 pilot jet, which is the
stock pilot jet. If he put in a #40 pilot jet, you are extremely rich in the
0-4000 rpm range. In my bored out, 12:1, ZX11 cammed, pod filtered motor, I
only use a #38 pilot @ 1 1/2 turns out on the mixture screws. A #40 pilot at
2 turns is way too much. If he gave you the #35 pilot jets back, you need to
put them back in, especially if you have the stock airbox, and set the
mixture screws at 3 turns out. Now for the main jet (150 main). If it is a
Keihin/Factory Pro main jet, a #150 is way too rich. Again as a reference,
in my highly modified motor, I only use a #140 main jet. The jet size
numbers don't cross reference exactly between the Keihin/FP and Dynojet
mainjets but a #150 would still be too large. The Dynojet main jet they
supply in their Stage 1 kit to be used with the stock airbox and a
performance exhaust is a #108. This makes you very rich in the 7500-11000
rpm range. There is no mention of replacing the needles or even shimming
them for proper mid-range (4000-7500 rpm) fueling. So, you're very rich on
the bottom and the top and probably lean in the middle. No wonder it runs
like crap. I suspect your bike was re-jetted with whatever they had laying
around, certainly not with a kit specifically for the GPZ. No kits for the
GPZ are supplied with pilot jets (you must purchase them separately) and no
kit has 150 main jets in it. The biggest main jet supplied with Factory
Pro's Stage 3 kit for the GPZ is a 142.
Alas, all is not lost. If memory serves me correctly, you have a
performance exhaust and the stock airbox. Keep your eyes open for a Dynojet
Stage 1 jet kit on ebay, it works very well for your configuration. If you
didn't get the #35 pilot jets back, go here http://www.carbparts.com/ and
buy four of them for a Keihin CVK carburetor. When you feel up to it, I'll
walk you through installing the kit. It is not difficult at all, the hardest
part is getting the carb rack on and off the bike. You've learned the hard
way and I will reiterate it for everyone else's benefit here: YOU CANNOT
TRUST THIS KIND OF WORK TO A DEALER MECHANIC! IF YOU CAN'T DO IT YOURSELF,
DON'T DO IT! LEAVE WELL ENOUGH ALONE!
Bill, don't give up your GPZ for a $100 worth of parts and a couple
hours of your time. It'll run good again, really it will.
Steve in Western NY
'96 GPZ1100
'02 Daytona 955i
'08 KLR 650
"You Can't Fix Stupid", Ron White
----- Original Message -----
From: "Bill Magitz" <corbie at verizonmail.com>
To: <gpzlist at micapeak.com>
Sent: Tuesday, January 15, 2008 4:01 PM
Subject: more on MPG & carb settings
after reading the recent postings on mpg/miles per tankful I found out what
I already knew, my GPZ is not well. I had a jet kit installed and after a
few stops at mc shops I got it close but not to my liking. I get about
110-120 miles before I hit reserve ( mild riding , hitting the throttle will
yield less than 100 mile tankful ) which is @40 less than before jet kit and
tinkering which translates to 10-15 mpg less. also I'm spewing some serious
fumes wherever I go. see if this makes sense to anybody , the last mechanic
who set the carbs wrote this on the work order , 35 slow 40 slow 150 main
and 2 turns out on mixture , I'm to the point if I can't fix I won't keep
it. will the proper setting help me get the mileage I desire ? thanks much
to anybody who can pass info on, the GPZ is a blast to ride and I'd prefer
to keep it and upgrade the Intruder 700. --bill m in joisey still getting
out on the weekends !!!!
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