more on MPG & carb settings

Steve Northrop blackgpz at
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 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 
     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>
To: <gpzlist at>
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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