GPZ1100 Questions

[Steve P]

I have an '84 GPZ1100 that's had its airbox removed and 4 individual filters put on. The machine is fuel injected, what is the method for enriching the fuel mix? Anybody have a genuine Kawasaki 1984 GPZ1100 service manual for sale or know where I can get one? Also, if you can recommend any websites where parts can be obtained, it would be appreciated also.

[antiq]

You can check EBay for a manual. Why do you feel the mix needs to be richer? BTW Welcome Steve. Post up some pics of your ride.

[elr658]

It's open loop, speed density.

[Steve P]

Antiq,
Thanks for the quick response. I'm assuming the individual filters will allow more air to enter the engine making the mix leaner.
tks again,
Steve

[elr658]

Being as it doesn't have an O2 sensor for fuel correction and the computer doesn't allow for enrichment your assumption would be correct. The Kawasaki Turbo is your friend here, for the variable resistor wired inline to the temp sensor circuit. Ask the guy whose had four of them. Do a Google using the turbo instead of the GPz. I think Holeshot Performance made one.

[sidy]

G'Day,

The problem you face with the first generation EFI controllers is a lack of being able to change anything. If your reasonably clued up you could replace the ECU with a megasquirt EFI controller and that would bring the EFI into the 21st century and allow you to do all kinds of nice things.

I have a z1000G which predates your bike's EFI (Mine has port injection) and I intend to change the ECU over after I finish my z1000A2 rebuild and conversion to Megasquirt EFI this year.

I have some info on my web site if yuo are interested.


Sid Young
z900
1974 z1a, 1976 z900A4, 1978 z1000A2, 1980 z1000G,
1972 CB750, 1974 CB740K4
1984 GPz900R-A1 & 1985 GPz900R-A2

[Steve P]

Originally Posted by elr658

Being as it doesn't have an O2 sensor for fuel correction and the computer doesn't allow for enrichment your assumption would be correct. The Kawasaki Turbo is your friend here, for the variable resistor wired inline to the temp sensor circuit. Ask the guy whose had four of them. Do a Google using the turbo instead of the GPz. I think Holeshot Performance made one.

Thanks for the info, but we didn't find anything at Holeshot. Is this resistor you reference (Turbo), a stock Kawasaki part? Is this resistor manually adjusted to increase fuel enrichment? Have any other ideas as to where I might be able to obtain one? Thanks again for the help.

[techy]

Aftermarket ECU (like the megasquirt) is way to gain control. Like this one:
Turbo Kawasaki

[Lorcan]

The simplest way to richen up the fuelling is to fit an adjustable fuel pressure regulator and increase the fuel pressure to around 42psi (stock is 36psi). If this makes it too rich at idle you can adjust the throttle position sensor (TPS) anti-clockwise to weaken if off. You can buy adjustable FPRs off ebay or from any car performance shop.

The really trick way to adjust the fuelling without sacrificing the stock ECU and all it's functionality (gauges, tank display etc) and having to remap from scratch is to fit a Dynojet Powercommander 3. You can then get the bike fully mapped at any Dynojet dyno centre just like a modern bike for perfect fuelling all through the rev range. Instructions for doing this are on my site.

[82KZ305]

This has already been addressed, but it bears repeating. The best way to adjust your fuel/air ratio is with a new computer. Given that it is fuel injected you could always take it to a performance chop and have them remap the unit. You can also upgrade to larger spray injectors, but again your going to have to go back and have the computer adjusted to push more gas.

Easiest way honestly, is to either take it to a shop with the software for fuel sending unit remapping, or just buying an upgraded computer unit. If you go other ways trying to richen it up, your computer wont know whats going on and can cause your bike to start running horrible.

[Lorcan]

There's no-one I know of that can remap the stock ECU. It does not have an EPROM or EEPROM to map, it's too old and basic for that. There is no flashable memory and no swappable chip. The closest thing in spec is an 8 bit Motorola microprocessor of approx 1980 vintage. Good luck getting the map out of that one.

I've run both aftermarket ECUs and Powercommanders on GPzs and can tell you that the easiest way to get great results on a streetbike is with a Powercommander. Aftermarket ECUs like Megasquirt are great and have their uses (if you are swapping from carbs for example) but have a steep learning curve. On a streetbike already equipped with EFI it's not necessary, a PC3 will do everything you need.

[82KZ305]

Well a Powercommander unit on a fuel system that old is going to have problems. Powercommander units are designed for making 4 banger motors race ready. Are you planning on racing your bike?

And another thing that I totally even forgot about, dont richen your bike. Someone said going to 42 psi, DONT. There is a lot more making a bike that is running rich, run right. And basically if your talking about getting more power, you're wanting to run more fuel and air, not make it run rich. Running rich is too much fuel in the ratio. But by adding more fuel, your also going to need more spark, so bigger coils will be needed. Your whole igniton system might as well be upgraded as well. Then your charging system is gonna need an upgrade to go along with all the added power.

You're looking at dropping about 4 grand just to bump power. If its not powerful enough, then buy a bigger bike. JMHO

EDIT: Let me go into better detail. Forgive me if this gets really long. Sometimes Im rather long winded.

42 psi of fuel pressure from a regulator wont give you much of a noticeable difference. You may feel it a little bit, but not much. However, 42 psi is overkill on a 66ci engine. I had a 350 Chevy that was sitting pretty making 300rwhp at 35 psi. Most performance cars run close to 42 psi, with drag cars being an exception and they only run a little bit more.

Now if you were to put a fpr in and set it to 42 and tried to drive it, you would blow your injectors. Cheap tricks like bumping the psi on your fuel system may work on drag bikes, but not on street. You would end up blowing seals and pistons rings, eventually blowing your whole motor. It would start by the diaphragms in your injectors failing. Imagine trying to squeeze a grape through something like a pin hole. Then it would dump more gas then the engine could combust. That would lead to seals soaking in the excess gas and a detination in your motor, which would be a catastrophic failure at highway speeds.

If you are wanting power, I will go into that in a second. But if your motor is running too lean, and you are trying to richen it up to make it run properly, then more then likely your injectors are clogged. You could run injector cleaner, or pull them and clean them. Or even by new injectors.

Now if power is what you're after, consider this. Motor companies that make computer controlled vehicle systems tune them to run optimally at midrange performance. You can tweak little things to get a tiny amount of power out of them, but nothing major. To build real horsepower in something as old as these bikes are, you are gonna have to go very drastic.

I would start by replacing your computer system with something stand-alone. The MegaSquirt is a good option, but Im not sure if its stand-alone. But it is good nonetheless. From there, I would upgrade your fuel lines. Stainless braided are best for more pressure. Now into a bigger fuel rail. Then into bigger injectors. Im not sure what the standard rating is on the stock injectors, but somewhere around 300-350cc injectors would probably outflow stock. Then I would upgrade your fuel pump to something pumping at least 15lph more then stock. Then your also going to want to upgrade your throttle body to something thats a good 1/3 of an inch bigger then stock.

Now that takes care of your fuel system. Now your going to need more spark. A better ignition system, higher voltage regulator, bigger coils, stronger generator, and hotter spark plugs.

Now with the added fuel/air mixture, your going to need to be able to get the mixture in and out better. Stock ports for intake and exhaust arent big enough to handle such stress. So a good port and polish of your intake and exhaust will be in order. This means new intake runners as well as a new exhaust system. Bigger holes will be required for a bigger system. And while you at it, new cams to adjust the lift duration and stronger valves and springs, as well as retainers and rockers.

Now inside the motor, you would need new piston rings. Probably a good cleaning and honing of the cylinder walls. And while your at it, get it bored over and pump your piston size. Go ahead and stroke the whole motor. You're upgrading everything else, might as well right? New crankshaft. Better bearings.

Then you're going to have to rebuild the tranny to handle the new and improved power machine. And god knows what that would cost.

Now please dont think this is THE WAY you have to go about it. But its the best way to build power in an all motor set up and keep it streetable and safe for long distances. But all in all, your looking at close to $8000 or better, probably more, just to build more power. For that kind of coin you're better off buying a new more powerful bike.

Just tricking your computer into pushing more fuel at your injectors is not only dangerous but outright stupid. If you're more then a weekend warrior you will have disasterous failure and on the highway, it can kill you. If you want to risk your life, half *** it. But if you dont, then please listen to someone who has more experience building more horsepower out of all motor setups. No offense to Lorcan, but his claim to fame right now is the fact that hes got a trubo'd 750 running on an 1/8th mile. Drag ready and street ready power are two totally different things.

[elr658]

Unless you're in love with FI, a set of Keihin 33 CRs or VM33s will outrun any band aid you can apply to the fuel injection on that Conestoga Wagon.

[Lorcan]

Originally Posted by 82KZ305

No offense to Lorcan, but his claim to fame right now is the fact that hes got a trubo'd 750 running on an 1/8th mile. Drag ready and street ready power are two totally different things.

You're right, I only have 20 years experience of tuning GPzs, the fastest GPz750 turbo in the world (211mph) the quickest on motor (8.69 @ 162mph) and my streetbike makes 235hp yet starts and idles like a stocker with perfect street manners. What do I know!

[Andy the gringo]

Originally Posted by Lorcan

You're right, I only have 20 years experience of tuning GPzs, the fastest GPz750 turbo in the world (211mph) the quickest on motor (8.69 @ 162mph) and my streetbike makes 235hp yet starts and idles like a stocker with perfect street manners. What do I know!

Apparently not enough for this bunch of "EXPERTS" hahahaha this was hilarious.

[82KZ305]

Originally Posted by Lorcan

You're right, I only have 20 years experience of tuning GPzs, the fastest GPz750 turbo in the world (211mph) the quickest on motor (8.69 @ 162mph) and my streetbike makes 235hp yet starts and idles like a stocker with perfect street manners. What do I know!

....

I would figure that an "expert" such as you would know that more gas does not equal more power. It means more fouled plugs, less chance of passing emissions, and higher risk of mechanical failure. That may be acceptable for you when you only run your bikes an 1/8 mile at a time, but on the street in a sport cruiser that just dont fly.

[Lorcan]

I bow to your greater experience of your 350 Chevy and your cowhorned 305. I can only dream of owning such vehicles...

[Lorcan]

Ok, let's recap.

Your suggestions were to fit a new computer (expensive and tricky) or remap the stock one (impossible) or spend $8k on a motor (stupid).

Mine were to fit an adustable FPR (cheap, and a well known mod proven on hundreds of GPzs and other fuel injected bikes) or to fit a Powercommander (really cool and also works great but a bit more expensive).

Do we have an accurate summary?

[Andy the gringo]

This thread is like a train wreck in slow motion…..I want to look away, but I can’t. So here are my observations.

82KZ305 logs in 2 weeks ago having just purchased a 305 with questions about how to operate his ignition switch, lower his seat, replace his MX handlebars, put pods on his CV carbs etc. Fast forward 2 weeks and suddenly he would have us believe that he’s Pops Yoshimura with all kinds of sage advice on how to build up a fuel injected GPZ 1100. I realize this is the internet, but come on, get real, do you expect me to believe that in 2 weeks you have gained enough knowledge about vintage Kawasakis to offer advice to anyone?

Lorcan has been here a couple of days and in that short amount of time has already been told that he is a liar and he doesn't know what he is talking about. I have the advantage of having interacted with Lorcan on other forums in the past. I feel fortunate that someone like him is available to me since I own an old fuel injected bike. So far I haven’t had any problems with the FI system, but you can bet your bottom dollar that if and when I do, his brain is going to be the first one I pick to try and fix my problem.

It is all about credibility, some have it, some don’t and some never will.

[StarGate]

Why don't you all stop and take a few deep breaths or go for a walk. You've hijacked Steve's thread and turned it into a pecker measuring contest. Everyone has an opinion and you are entitled to it. Why not just focus on the problem, give your suggestion, and let it go at that. You don't need to criticize anyone else for their suggestion, just offer your own if you have a different idea.